Type Certification Procedures for Changed Products

Part VII

Department of Transportation

_______________________________________________________________________

Federal Aviation Administration

_______________________________________________________________________

14 CFR Parts 11, 21, and 25

Type Certification Procedures for Changed Products; Proposed Rule

Rules

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 11, 21, and 25

[Docket No. 28903; Notice No. 97-7]

RIN 2120-AF68

Type Certification Procedures for Changed Products

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to amend the procedural regulations for

the certification of changes to type certificated products. The

amendments are need to address the trends toward fewer products that

are of completely new design and more products with repeated changes of

previously approved designs. Safety would be enhanced by applying the

latest airworthiness standards, to the greatest extent practicable, for

the certification of design changes of aircraft engines, and

propellers.

DATES: Comments must be received on or before September 2, 1997.

ADDRESSES: Comments on this proposal must be mailed in triplicate to:

Federal Aviation Administration, Office of the Chief Counsel,

Attention: Rules Docket (AGC-200, Docket No. 28903, 800 Independence

Avenue SW, Washington, DC 20591, or delivered in person to room 915G at

the same address. Comments may also be submitted electronically to the

following Internet address: [email protected]. Comments submitted

must be marked: Docket No. 28903. Comments may be inspected in room

915G weekdays, except Federal holidays, between 8:30 am and 5:00 pm.

FOR FURTHER INFORMATION CONTACT: Lyle C. Davis, Certification

Procedures Branch (AIR-110), Aircraft Certification Service, Federal

Aviation Administration, 800 Independence Avenue, SW, Washington, DC

20591, telephone (202) 267-9588.

ted]. Comments submitted

must be marked: Docket No. 28903. Comments may be inspected in room

915G weekdays, except Federal holidays, between 8:30 am and 5:00 pm.

FOR FURTHER INFORMATION CONTACT: Lyle C. Davis, Certification

Procedures Branch (AIR-110), Aircraft Certification Service, Federal

Aviation Administration, 800 Independence Avenue, SW, Washington, DC

20591, telephone (202) 267-9588.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the proposed

rulemaking by submitting such written data, views, or arguments as they

may desire. Commenters should identify the regulatory docket or notice

number and submit comments in triplicate to the Rules Docket at the

address specified above. All comments will be considered by the

Administrator before action on the proposed rulemaking is taken. The

proposals contained in this notice may be changed in light of the

comments received. All comments will be available in the Rules Docket,

both before and after the closing date for comments, for examination by

interested persons. A report summarizing each substantive public

contact with Federal Aviation Administration (FAA) personnel concerning

this rulemaking will be filed with the docket. Commenters wishing the

FAA to acknowledge receipt of their comments must submit with those

comments a self-addressed, stamped postcard on which the following

statement is made: ``Comments to Docket No 28903.'' The postcard will

be dated and time stamped and returned to the commenter.

Availability of NPRMs

dministration (FAA) personnel concerning

this rulemaking will be filed with the docket. Commenters wishing the

FAA to acknowledge receipt of their comments must submit with those

comments a self-addressed, stamped postcard on which the following

statement is made: ``Comments to Docket No 28903.'' The postcard will

be dated and time stamped and returned to the commenter.

Availability of NPRMs

An electronic copy of this document may be downloaded using a

modern and suitable communications software from the FAA regulations

section of the Fedworld electronic bulletin board service (telephone:

703-321-3339), the Federal Register's electronic bulletin board service

(telephone: 202-512-1661), or the FAA's Aviation Rulemaking Advisory

Committee Bulletin Board service (telephone: 202-267-5948).

Internet users may reach the FAA's web page at http://www.faa.gov

or the Federal Register's web page at http://www.access.gpo.gov/

su__docs for access to recently published rulemaking documents.

Any person may obtain a copy of this NPRM by submitting a request

to the Federal Aviation Administration, Office of Rulemaking, ARM-1,

800 Independence Avenue SW, Washington, DC 20591; or by calling (202)

267-9680. Communications must identify the notice number or docket

number of this NPRM.

Persons interested in being placed on the mailing list for future

NPRM's should request from the above office a copy of Advisory Circular

No. 11-2A, Notice of Proposed Rulemaking Distribution System, that

describes the application procedure.

Background

Statement of the Problem

20591; or by calling (202)

267-9680. Communications must identify the notice number or docket

number of this NPRM.

Persons interested in being placed on the mailing list for future

NPRM's should request from the above office a copy of Advisory Circular

No. 11-2A, Notice of Proposed Rulemaking Distribution System, that

describes the application procedure.

Background

Statement of the Problem

Under the regulations in effect prior to the early 1940's, an

applicant for a change product, such as an alternate engine

installation, was required to apply for a new type certificate and

comply with the standards current at the time of application. This did

not present an unreasonable burden on the applicant then because the

airworthiness standards did not change appreciably over short periods

of time. That is, the standards current at the time of an application

were essentially the same as those with which the original product had

to comply. Since the early 1940's, however, rapid changes in technology

have resulted in significant changes in the airworthiness standards

over relatively short periods of time. Therefore, an applicant for an

extensive change to a type certificated product, which required a new

type certificate, could be faced with complying with safety standards

that varied considerably from the standards for the original product.

To relieve this situation, the FAA's predecessor agency required an

application for a new type certificate only if the change was quite

extensive.

In recent years, a trend has developed towards fewer products that

are of such significantly new design that a new type certificate is

required. In many cases, over a period of time, a series of changes

could permissively be made to a product by amending its original type

certificate such that the resultant model is substantially different

from the original model

change was quite

extensive.

In recent years, a trend has developed towards fewer products that

are of such significantly new design that a new type certificate is

required. In many cases, over a period of time, a series of changes

could permissively be made to a product by amending its original type

certificate such that the resultant model is substantially different

from the original model. Although each changed product in such a series

of changes may differ little from its immediate predecessor, the

changes could collectively result in a product with substantial

differences from the original product. As a result, many newly

manufactured aeronautical products are not being required to comply

with the more recent airworthiness standards. The procedural

regulations need to be changed to correspond with this trend toward

fewer new type certificates.

History of Type Certification

Title 49 U.S.C. Sec. 44701 authorizes the FAA Administrator to

promote safety of flight of civil aircraft in air commerce by

prescribing and revising minimum standards governing the design and

construction of aircraft, aircraft engines, and propellers as may be

required in the interest of safety, and such minimum standards

governing appliances as may be required in the interest of safety.

Under 49 U.S.C. Sec. 44704, the FAA may issue type certificates,

including supplemental type certificates, for aircraft, aircraft

engines, and propellers. The FAA may prescribe in any such certificates

the duration of the certificate, and the terms, conditions, and

limitations as required in the interest of safety.

The general certification procedures for products (aircraft,

aircraft engines, and propellers) and parts are set forth in 14 CFR

part 21 (part 21). As described

ntal type certificates, for aircraft, aircraft

engines, and propellers. The FAA may prescribe in any such certificates

the duration of the certificate, and the terms, conditions, and

limitations as required in the interest of safety.

The general certification procedures for products (aircraft,

aircraft engines, and propellers) and parts are set forth in 14 CFR

part 21 (part 21). As described

in Secs. 21.13 and 21.15, any interested person may apply for a type

certificate by submitting an application accompanied by the required

documentation to the FAA. Sections 21.16 through 21.21, 21.101, and

21.115 specify certain regulations and designate the applicable

airworthiness standards for type certification of both new and changed

products.

Section 21.17 designates the applicable regulations for the

issuance of type certificates. In order to be issued a type

certificate, the applicant must show that the product complies with the

airworthiness standards contained in one of the following 14 CFR parts,

as applicable; part 23 for normal, utility, acrobatic, and commuter

category airplanes; part 25 for transport category airplanes; part 27

for normal category rotorcraft; part 29 for transport category

rotorcraft; part 31 for manned free balloons; part 33 for aircraft

engines; part 35 for propellers; and part 21 (Sec. 21.17 (b) and (f))

for special classes of aircraft and primary category aircraft

respectively.

The airworthiness standards in these parts of the regulations may

be amended as needed to reflect continually changing technology,

correct design deficiencies, and provide for safety enhancements. An

applicant for a type certificate is required under current Sec. 21.17,

with certain exceptions, to show that the product meets the applicable

airworthiness standards that are in effect at the date of the

application

ndards in these parts of the regulations may

be amended as needed to reflect continually changing technology,

correct design deficiencies, and provide for safety enhancements. An

applicant for a type certificate is required under current Sec. 21.17,

with certain exceptions, to show that the product meets the applicable

airworthiness standards that are in effect at the date of the

application. The exceptions include instances in which the

Administrator specifies otherwise or in which the applicant either

elects or is required under specific circumstances to comply with later

effective amendments. In addition, the Administrator may prescribe

special conditions.

Under Sec. 21.16, special conditions may be prescribed if the

Administrator finds that the existing airworthiness standards do not

contain adequate or appropriate safety standards because of novel or

unusual design features of the product to be type certificated relative

to the design features considered in the applicable airworthiness

standards. Also, under Sec. 21.21(b)(1), if any applicable

airworthiness standards are not complied with, an applicant may

nevertheless be entitled to a type certificate if the Administrator

finds that those standards not complied with are compensated for by

factors that provide an equivalent level of safety. Such determinations

are commonly referred to as ``equivalent safety findings'' and are made

with respect to the level of safety intended by the applicable

standard. In addition, under Sec. 21.21(b)(2), an applicant may be

denied a type certificate if the Administrator finds an unsafe feature

or characteristic of the aircraft for the category in which type

certification is requested, even though the aircraft may comply fully

with the applicable airworthiness standards.

Taken together Secs

espect to the level of safety intended by the applicable

standard. In addition, under Sec. 21.21(b)(2), an applicant may be

denied a type certificate if the Administrator finds an unsafe feature

or characteristic of the aircraft for the category in which type

certification is requested, even though the aircraft may comply fully

with the applicable airworthiness standards.

Taken together Secs. 21.16, 21.17, and 21.21 designate the

applicable airworthiness regulations for type certification and

accommodate those circumstances when the airworthiness standards do not

adequately cover the design features of a product. These sections

recognize and balance the following four important considerations:

(1) The obligation of the FAA, under 49 U.S.C. Sec. 44701, to keep

the airworthiness standards required in the interest of safety, (i.e.,

parts 23, 25, 27, 29, 31, 33 and 35) as current as practicable;

(2) The type certificate applicant needs to know, early in a

certification program, what the applicable airworthiness standards will

be in order to finalize the detailed design of its product and to

enable the applicant to make reasonable performance guarantees to its

potential customers;

(3) In the interest of safety, rapid technological advances

presently being made by the civil aircraft industry necessitate that

the FAA be able to issue special conditions to address novel or unusual

design features that it has, as yet, not had an opportunity to address

in the airworthiness standards through the general rulemaking process,

or to address novel or unusual design features that were not considered

by the appropriate airworthiness standards applicable to changes to

type certificates; and

necessitate that

the FAA be able to issue special conditions to address novel or unusual

design features that it has, as yet, not had an opportunity to address

in the airworthiness standards through the general rulemaking process,

or to address novel or unusual design features that were not considered

by the appropriate airworthiness standards applicable to changes to

type certificates; and

(4) To allow flexibility in design. Wherever possible, the

airworthiness standards of 14 CFR Chapter 1, subchapter C, are

intentionally objective in nature, and the procedural regulations

permit design changes over the operational life of a product.

Originally, the FAA would issue special conditions informally as an

interpretation of the ``no unsafe feature or characteristic''

regulations; however, in 1967, the FAA formalized the process with the

adoption of Sec. 21.16. As provided in that section, special conditions

are issued as regulations in accordance with public comment provisions

of 14 CFR part 11 (part 11). The adoption of Sec. 21.16 extended the

special condition process to include aircraft engines and propellers.

The provision in Sec. 21.21(b)(2), that a type certificate would be

issued for an aircraft only if no unsafe feature or characteristic

existed, remained unchanged.

The phrase ``novel or unusual'' is used in describing design

features for the issuance of special conditions under the provisions of

Sec. 21.16. These design features involve a state of technology not

considered for the applicable airworthiness standards at the time they

were written; in some areas, the state of the regulations may lag the

state of the art of new designs. This disparity is due to both the

rapidity in which the state of the art is advancing in civil

aeronautical design and the need to develop a sufficient experience

base with new technology before proceeding with general rulemaking

ed for the applicable airworthiness standards at the time they

were written; in some areas, the state of the regulations may lag the

state of the art of new designs. This disparity is due to both the

rapidity in which the state of the art is advancing in civil

aeronautical design and the need to develop a sufficient experience

base with new technology before proceeding with general rulemaking.

Therefore, there may be instances in which special conditions are

required for design features considered ``state of the art'' in the

aircraft industry. Conversely, many new design features that might be

thought of as ``novel or unusual'' in the context of the product's

original certification basis may already be covered by existing

regulations, thereby obviating the need to issue special conditions.

This fact is recognized in existing Sec. 21.101(b)(1).

For example, in 1980, the holder of a small airplane type

certificate who installed turboprop engines in place of reciprocating

engines did so by complying with appropriate later regulations. Because

appropriate regulations were available for the installation of

turboprop engines, special conditions were not issued for installation

of the engines. These changes were made through the FAA issuing an

amendment to the type certificate originally issued in 1964. The

airworthiness regulations, part 23, were changed to accommodate

turboprop engines in 1969.

Special conditions are not issued for general upgrading of the

applicable airworthiness standards to achieve a higher level of safety.

Whenever the FAA concludes that a compelling need exists for a higher

level of safety in type designs, rulemaking is proposed in accordance

with the general rulemaking procedures of part 11, the Administrative

Procedure Act, and Executive Order 12866. Finally, Secs. 23.2, 25.2,

27.2, and 29.2 provide retroactive regulations in the airworthiness

standards

to achieve a higher level of safety.

Whenever the FAA concludes that a compelling need exists for a higher

level of safety in type designs, rulemaking is proposed in accordance

with the general rulemaking procedures of part 11, the Administrative

Procedure Act, and Executive Order 12866. Finally, Secs. 23.2, 25.2,

27.2, and 29.2 provide retroactive regulations in the airworthiness

standards. A complete statement of the FAA intent with respect to the

application of special conditions is found in the preamble to amendment

51 to Part 21 (45 FR 60154, September 11, 1980). That intent is in no

way changed by the proposals herein.

Sometimes new airworthiness standards contain provisions that, in

the interest of safety, should be applied

retroactively to existing aircraft. Typically this is accomplished by

proposing changes to 14 CFR parts 121 and 135, and sometimes part 91,

through rulemaking procedures.

History of Type Certification of Changes

Part 21 designates the applicable airworthiness standards for

changed products. Section 21.19 describes the circumstances in which an

applicant for type certification of a changed product must apply for a

new type certificate. Prior to the early 1940's, an applicant for a

changed product, such as an airplane with an alternate engine

installation, was required to apply for a new type certificate. The

regulations in effect prior to the early 1940's required an applicant

for a changed product to apply for a new type certificate for a change

such as an alternate engine installation. When a new type certificate

was required, the applicant had to comply with the standards current at

the time of application. This did not present an unreasonable burden on

the applicant then because the airworthiness standards did not change

appreciably over a period of time. The then current standards were,

therefore, essentially the same as those with which the original

product had to comply

en a new type certificate

was required, the applicant had to comply with the standards current at

the time of application. This did not present an unreasonable burden on

the applicant then because the airworthiness standards did not change

appreciably over a period of time. The then current standards were,

therefore, essentially the same as those with which the original

product had to comply. Later, more rapid changes in technology resulted

in significant changes in the airworthiness standards over relatively

short periods of time. An applicant for a type certificate for a

changed product could thus be faced with complying with airworthiness

standards that varied considerably from those with which the original

product complied. In some instances, the differences in standards could

be so great that an applicant would be discouraged from making any

changes, including changes that would, in themselves, contribute to the

safety of the product. To relieve this situation, by the early 1940's,

an application for a new type certificate was required only if the

change was extensive.

Section 21.19(a) requires a new type certificate when a change is

considered so extensive that a substantially complete investigation of

compliance with the regulations is required. In addition, Secs. 21.19

(b), (c), and (d) provide specific types of changes that require an

application for a new type certificate because those types had already

been determined to be substantial per Sec. 21.19(a). For a normal,

utility, acrobatic, commuter, or transport category aircraft, paragraph

that a substantially complete investigation of

compliance with the regulations is required. In addition, Secs. 21.19

(b), (c), and (d) provide specific types of changes that require an

application for a new type certificate because those types had already

been determined to be substantial per Sec. 21.19(a). For a normal,

utility, acrobatic, commuter, or transport category aircraft, paragraph

(b) requires a new aircraft type certificate if the proposed change is

(1) in the number of engines or rotors, or (2) to engines or rotors

using different principles of propulsion or to rotors using different

principles of operation. Similarly, paragraph (c) requires a new engine

type certificate if the proposed change is in the engine's principle of

operation, and paragraph (d) requires a new propeller type certificate

if the proposed change is in the number of blades or in the principle

of pitch change operation.

The basis for Sec. 21.19(b)(1) originated in the early 1950's

following the issuance of an amended type certificate to an applicant

who altered a popular single-engine, four-passenger, light airplane

into a twin-engine model. Although that conversion was approved by an

amendment to the original type certificate, the agency recognized that

the conversion from one to two engines added considerable complexity to

the airplane and greatly affected its handling characteristics.

Therefore, the predecessor of Sec. 21.19(b)(1) was adopted requiring a

new type certificate for a change in the number of engines or rotors.

The regulatory language was broad enough in scope to include any change

in the number of engines or rotors whether such changes would simplify

or add complexity to the type design.

The FAA does not require an applicant to apply for a new type

certificate to add small auxiliary engines to an aircraft

was adopted requiring a

new type certificate for a change in the number of engines or rotors.

The regulatory language was broad enough in scope to include any change

in the number of engines or rotors whether such changes would simplify

or add complexity to the type design.

The FAA does not require an applicant to apply for a new type

certificate to add small auxiliary engines to an aircraft. In the

1960's with the development of small turbojet engines to be used as

auxiliary engines, the FAA defined a jet engine that develops less than

50 percent of the static thrust developed by one of the primary

propulsion engines as an auxiliary engine. The FAA considers the

``number of engines'' as used in Sec. 21.19(b)(1) to refer to the

number of primary propulsion engines and not to any auxiliary engines

to be installed. The FAA has issued a large number of exemptions from

the regulation concerning a change in the number of engines.

Prior to 1957, predecessors of current Sec. 21.19(b)(2) stated that

an applicant must make a new application for type certificate if the

proposed change was to engines employing different principles of

operation or propulsion. This meant that an applicant desiring to

replace reciprocating engines with the same number of turbopropeller

engines would have to apply for a new type certificate. During that

period, it was recognized that considerable advances in safety,

reliability, and passenger comfort could be realized by replacing

reciprocating engines in certain transport category airplanes with

turbopropeller engines. In order to encourage such beneficial changes,

the reference to different principles of operation was deleted in 1957

for transport category airplanes. As a result, an applicant may be

granted approval for a conversion of this nature without applying for a

new type certificate providing the applicant complies with certain

later standards applicable to turbine-powered airplanes

peller engines. In order to encourage such beneficial changes,

the reference to different principles of operation was deleted in 1957

for transport category airplanes. As a result, an applicant may be

granted approval for a conversion of this nature without applying for a

new type certificate providing the applicant complies with certain

later standards applicable to turbine-powered airplanes. In the

broadest sense, all powered airplanes achieve propulsion by

accelerating a mass of air and/or exhaust gases. In the narrower

context of Sec. 21.19(b)(2), however, ``principles of propulsion''

means propeller-driven versus turbojet.

Section 21.19(b)(2) also states that an applicant must make a new

application for a type certificate if the proposed change is to rotors

employing different principles of operation or propulsion. The FAA is

not aware of any instance in which this specific section was the basis

for requiring an application for a new type certificate; any change of

this nature, together with all related changes, would have been so

extensive that a new type certificate would have been required under

the provisions of Sec. 21.19(a).

The FAA has never granted any exemptions from the regulation for a

new aircraft type certificate for a change to engines or rotors using

different principles of propulsion. Similarly, no exemptions have been

granted from the engine or propeller type certificate regulations for

changes involving the principle of engine operation, for changes in the

number of propeller blades, or for changes in the principle of pitch

change operation.

Under Sec. 21.101, the original type certificate may be amended to

include changes to the product when the applicant demonstrates that it

complies with the same airworthiness standards as the original product

plus appropriate special conditions, and the change does not warrant

making a new application for a type certificate under Sec. 21.19.

Because Sec. 21.101 (a) and (b) are incorporated by reference in

Sec

the original type certificate may be amended to

include changes to the product when the applicant demonstrates that it

complies with the same airworthiness standards as the original product

plus appropriate special conditions, and the change does not warrant

making a new application for a type certificate under Sec. 21.19.

Because Sec. 21.101 (a) and (b) are incorporated by reference in

Sec. 21.115, these procedures are equally applicable to persons

applying for supplemental type certificates.

Section 21.101(a) requires that an applicant for a change to a type

certificate must comply with either the regulations incorporated by

reference in the type certificate or the applicable regulations in

effect at the date of application, plus any other amendments the

Administrator finds to be directly related. The ``regulations

incorporated by reference'' are the regulations that were the

certification basis for the original issuance of the type certificate.

They are frequently referred to as the ``original certification

basis.''

If an applicant chooses to show compliance with the regulations in

effect at the date of the application for the change, the applicant

must also comply with any other amendments that are directly related.

In some instances, a regulation may be amended to become less

stringent, but a related regulation may become more stringent. In a

situation of this nature, the applicant must also comply with the

related compensating regulation as well. Current Sec. 21.101(a) does

not otherwise require compliance with later amendments and does not

grant the Administrator the authority to require compliance with later

regulations as a method to increase the level of safety of a product.

An applicant for a change to a type certificated product is

responsible for showing that the entire product, as altered, not just

that the change itself, complies with the certification basis, because

areas that have not been changed may be affected by the change

Administrator the authority to require compliance with later

regulations as a method to increase the level of safety of a product.

An applicant for a change to a type certificated product is

responsible for showing that the entire product, as altered, not just

that the change itself, complies with the certification basis, because

areas that have not been changed may be affected by the change.

However, the applicant need not resubstantiate those areas of the

product where the original substantiation has not been invalidated by

the change.

Section 21.101(b) pertains to changes for which the regulations

incorporated by reference do not provide adequate standards. Such

changes generally involve features that were not envisaged at the time

the regulations incorporated by reference were adopted and are,

therefore, novel or unusual with respect to those regulations. For

these changes, the applicant must comply with regulations in effect at

the date of application for the change as found necessary to provide a

level of safety equal to that established by the regulations

incorporated by reference. In this case, the applicant is not able to

select any amendment of the regulation it chooses between those

incorporated by reference and those in existence at the date of the

application. When regulations in effect at the date of application for

the change fail to provide adequate standards, the applicant must

comply with special conditions to provide a level of safety equal to

that established by the regulations incorporated by reference.

Trends in Type Certification of Changes

ses between those

incorporated by reference and those in existence at the date of the

application. When regulations in effect at the date of application for

the change fail to provide adequate standards, the applicant must

comply with special conditions to provide a level of safety equal to

that established by the regulations incorporated by reference.

Trends in Type Certification of Changes

In recent years, a trend has developed toward fewer products that

are of completely new designs, which would require new type

certificates. Over a period of time, a series of changes to an original

product may have been made so that the current model is substantially

different from the original model. Although each changed product in

such a series of changes may differ little from its immediate

predecessor, the changes could result collectively in a product with

substantial differences from the original product.

For example, one model originally manufactured as a normal category

airplane with two reciprocating engines has been changed through a

series of alterations to incorporate turbopropeller engines, a

stretched and heightened fuselage, a tricycle landing gear, a modified

wing planform and a 42 percent increase in maximum takeoff weight. In

this particular case, the majority of changes were made through the

FAA's issuing supplemental type certificates to modifiers other than

type certificate holder. However, the type certificate holder could

have made the same incremental changes without applying for a new type

certificate each time.

In another instance, a type certificate holder effected significant

changes in the design of a turbojet transport category airplane without

obtaining a new type certificate by making a series of changes to its

existing type certificate. Each incremental change, by itself, was

determined not to be so extensive as to require a new type certificate

under Sec. 21.19(a)

pe

certificate each time.

In another instance, a type certificate holder effected significant

changes in the design of a turbojet transport category airplane without

obtaining a new type certificate by making a series of changes to its

existing type certificate. Each incremental change, by itself, was

determined not to be so extensive as to require a new type certificate

under Sec. 21.19(a). This airplane evolved into a configuration

approximately 40 percent greater in fuselage length and with a 92

percent greater maximum takeoff weight than the original model. These

changes, which have been incorporated into newly manufactured

airplanes, are possible because the FAA issued amendments to the type

certificate.

Another trend in manufacturing is to keep products in production

over several decades. Some currently manufactured transport category

airplanes have, for example, evolved from airplane models originally

type-certificated 25 years ago. This does not imply that those

airplanes are ``unsafe,'' because they do, in practice, have features

that address the intent of most of the current airworthiness standards.

However, current procedural regulations (part 21) do not require that

changed products comply with the current airworthiness standards.

The basic premise behind the FAA's current policies for the

procedures and airworthiness standards for type certification is that

the highest possible degree of safety in the public interest, should be

achieved by products being certificated at any given time. In dealing

with this premise, the FAA has had to continually weigh the desire for

the highest level of safety with the cost to the manufacturers,

operators, and traveling public for achieving that highest possible

degree of safety in the public interest. This balance between safety

and cost has been exacerbated by the introduction of highly

sophisticated products whose development and manufacture have become

enormously expensive

has had to continually weigh the desire for

the highest level of safety with the cost to the manufacturers,

operators, and traveling public for achieving that highest possible

degree of safety in the public interest. This balance between safety

and cost has been exacerbated by the introduction of highly

sophisticated products whose development and manufacture have become

enormously expensive. This is one reason why, as stated before,

manufacturers choose to produce more and more changed products that, by

the FAA regulations, are not required to have new type certificates.

The FAA maintains that the issue should not be whether a product is

produced under a new type certificate or an amended one. The issue is

whether or not the level of safety of the product, embodied in the

airworthiness standards it complies with, is as high as practicable. In

addition, to require areas unaffected by the change to comply with the

later standards is not only unreasonably costly but may reduce the

level of safety of the product due to unforeseen developmental

problems. The manufacturers are constantly issuing service information

that describes approved alterations that users may make to improve the

level of safety of the product. Thus, it is common place that products

in service today possess a level of safety significantly greater than

that embodied in their certification basis.

When establishing the highest practicable level of safety for a

changed product, the FAA has determined that it is appropriate to

assess the service history of a product as well as the later

airworthiness standards. It makes little sense to mandate changes to

well understood designs, whose service experience has been acceptable,

merely to comply with new standards. The clear exception to this

premise is where the new standards were issued to address a deficiency

in the design in question or where the service experience is not

applicable to the new standards

as well as the later

airworthiness standards. It makes little sense to mandate changes to

well understood designs, whose service experience has been acceptable,

merely to comply with new standards. The clear exception to this

premise is where the new standards were issued to address a deficiency

in the design in question or where the service experience is not

applicable to the new standards. This consideration of airworthiness

standards and service experience should form the basis for developing

the ceritifcaiton basis for a change in a product.

It can be argued, for consistency, that new airworthiness standards

should apply across the board to the entire aircraft fleet; however,

application of new standards would not be practicable in every case.

Although newly designed aircraft are required to meet all applicable

current airworthiness standards, in many cases a product being changed,

for which only an amended type certificate is needed, is required to

meet only the standards referenced in the original type certificate.

Thus, there may be a considerable difference between the standards

required for a new product and for a product undergoing change. A

product undergoing change that met the applicable standards at the time

of original type certification is not currently required to meet more

current airworthiness standards except in those instances where

retroactive regulations have been issued or the applicant elects to

comply with later amendments.

In recent rulemakings, the FAA has carefully considered whether

corresponding retroactive action is warranted whenever a change to the

airworthiness standards for type certification was proposed

s not currently required to meet more

current airworthiness standards except in those instances where

retroactive regulations have been issued or the applicant elects to

comply with later amendments.

In recent rulemakings, the FAA has carefully considered whether

corresponding retroactive action is warranted whenever a change to the

airworthiness standards for type certification was proposed. In those

cases where it has been deemed that a safety benefit commensurate with

the cost could be achieved, the rulemaking has also included a proposal

to change the relevant operating regulations to require newly

manufactured airplanes and/or airplanes in service to comply

retroactively with the new standards, regardless of whether such

compliance would be required as a condition of type certification. For

instance, some of the regulations implemented in recent revisions to

part 25 for newly manufactured airplanes were required for the existing

fleet and were implemented in the operating regulations, such as part

121.

In 1965, the FAA granted an exemption from the provisions of

Sec. 21.19(b)(1) to permit conversion of a four-engine amphibian to a

twin-engine configuration without the applicant applying for a new type

certificate. During the 1980's three applicants petitioned for

exemptions from the above regulations so they could convert Boeing 727

airplanes from the original three-engine configuration to ones with two

engines without having to apply for new type certificates. Another

applicant petitioned for a similar exemption to replace the four

engines of a Lockheed 1329 Jetstar aircraft with two engines of more

recent vintage. The FAA granted each exemption with the condition that

the petitioner comply with the provisions of then current part 25 in

all areas, systems, components, equipment, or appliances affected by

the conversion

y for new type certificates. Another

applicant petitioned for a similar exemption to replace the four

engines of a Lockheed 1329 Jetstar aircraft with two engines of more

recent vintage. The FAA granted each exemption with the condition that

the petitioner comply with the provisions of then current part 25 in

all areas, systems, components, equipment, or appliances affected by

the conversion.

The FAA also granted a number of exemptions that permitted

increasing the number of engines without the need for the applicants to

obtain new type certificates. In 1985, an applicant received an

exemption to replace two reciprocating engines in Grumman Albatross

amphibians with four turbo propeller engines without having to obtain a

new type certificate. In granting the exemption, the FAA concurred that

the alteration should improve the Albatross by increasing safety,

increasing power plant reliability, and improving overall aircraft

efficiency. The exemption noted that compliance with Sec. 21.19(b)(1)

would have required changes to some basic systems that had provided

satisfactory performance for many years and had contributed to the

safety record of those airplanes. Applying then-current regulations to

components and systems not affected by the installation of the four

engines would have been time consuming and costly, and would not

necessarily have contributed any safety benefits. As with the

exemptions to reduce the number of engines, this exemption was granted

with the condition that the petitioner comply with the provisions of

then current part 25 in all areas, systems, components, equipment, or

appliances affected by the conversion.

A similar exemptions also granted in 1989 to enable an applicant to

increase the number of engines from one to two in certain Bel 206

series rotorcraft. The petitioner cited the increased safety afforded

by a twin-engine configuration in the event a failure occurred during

hover, and also the enhanced altitude performance

tems, components, equipment, or

appliances affected by the conversion.

A similar exemptions also granted in 1989 to enable an applicant to

increase the number of engines from one to two in certain Bel 206

series rotorcraft. The petitioner cited the increased safety afforded

by a twin-engine configuration in the event a failure occurred during

hover, and also the enhanced altitude performance. As a condition of

the grant of exemption, the applicant was required to show that the

altered rotorcraft complied with the standards of part 27 in effect at

the date of application for the change for all areas, systems,

equipment, or appliances that were changed or significantly affected by

the change.

These exemptions point out an important feature that has been

included in this proposed rulemaking. The number of engines is not, in

itself, an appropriate criterion for requiring an application for a new

type certificate as long as the type design complies with the

regulations effective at the date of the application for the change in

those areas changed or affected by the change.

Recent FAA Actions

Apart from safety considerations, there has also been a growing

international concern that some changed products are given an unfair

competitive advantage over those that are of new design and must comply

with later standards.

Because of these concerns, the FAA participated in the activities

of an ad hoc committee sponsored by the Aerospace Industries

Association of America, known as the International Certification

Procedures Task Force (ICPTF)

growing

international concern that some changed products are given an unfair

competitive advantage over those that are of new design and must comply

with later standards.

Because of these concerns, the FAA participated in the activities

of an ad hoc committee sponsored by the Aerospace Industries

Association of America, known as the International Certification

Procedures Task Force (ICPTF). In addition to the FAA, this task force

included representatives of the European Joint Aviation Authorities,

Transport Canada, Aerospace Industries Association of America, Air

Transport Association of America, General Aviation Manufacturers

Association, International Air Transport Association, Association

Europeenne des Constructeurs de Materiel Aerospatial, Aerospace

Industries Association of Canada, Air Line Pilots Association, and

Association of European Airlines.

The ICPTF was organized to develop the philosophy and the necessary

regulatory text and advisory material that would provide for the

implementation of later regulatory amendments applicable to

aeronautical products undergoing change, products in production, and

products in service. The specific tasks of the ICPTF were: (1) Develop

the type certification philosophy for changes to aeronautical products,

including revisions to the regulations and associated advisory

material; (2) Develop the necessary guidance information on the use of

``service experience'' in the type certification process; and (3)

Develop a method to evaluate the safety impact and cost effectiveness

of revisions to the airworthiness standards.

In order to develop future proposed safety standards by using a

system-type analysis, the FAA chartered a committee of safety experts,

known as the Aviation Rulemaking Advisory Committee (ARAC), on February

5, 1991. This committee established the International Certification

Procedures Working Group, which consists of the original ad hoc

committee formerly known as the ICPTF

hiness standards.

In order to develop future proposed safety standards by using a

system-type analysis, the FAA chartered a committee of safety experts,

known as the Aviation Rulemaking Advisory Committee (ARAC), on February

5, 1991. This committee established the International Certification

Procedures Working Group, which consists of the original ad hoc

committee formerly known as the ICPTF. The task assigned to this

working group was to present to ARAC various proposals pursuant to its

area of expertise. ARAC then had the option to submit these

recommendations to the FAA, and the FAA would decide whether or not to

issue a proposal based on the ARAC recommendations.

The Working Group presented to ARAC an NPRM and associated advisory

material concerning the type certification procedures for changes to

aeronautical products, newly manufactured products, and products

already in service. ARAC, in turn, submitted these documents as

recommendations to the FAA. The FAA recognizes the difficult task the

working group undertook in the effort to address the issues in this

proposed rule and in the advisory material. Much of the work done

within the working group could not have been accomplished without the

assistance of working group members representing the aviation

community. The rulemaking proposed by the FAA in this notice reflects

the ARAC recommendations in the type certification procedures for

changed products with only minor changes. Similar proposed changes have

been published by the Joint Aviation Authorities.

FAA's Proposed Policy on Changed Products

ve been accomplished without the

assistance of working group members representing the aviation

community. The rulemaking proposed by the FAA in this notice reflects

the ARAC recommendations in the type certification procedures for

changed products with only minor changes. Similar proposed changes have

been published by the Joint Aviation Authorities.

FAA's Proposed Policy on Changed Products

The FAA intends to require that applicants for changes to type

certificated products show compliance with the latest amendments to the

airworthiness standards that are applicable to the product being

changed. Exceptions to requiring a showing of compliance with the later

amendments would be provided to accommodate variations in the kinds of

type certificated products, of changes to these type certificated

products, and revisions of the airworthiness standards. These

exceptions would permit compliance with regulations issued prior to the

regulations in effect at the date of the application for the change.

This proposed rulemaking would amend the type certification

procedures for changes to type certificated products to bring the

certification basis for changed products and for newly type

certificated products closer together. The intent is to ensure that

when an essentially new product is developed through a series of

changes, regardless of the extent of each change, the final product

achieves a level of safety similar to that of a comparable new product.

This concept will be tempered with the knowledge that a good design

does not become unsafe as soon as a new regulation has been published.

Some differences may be acceptable between the certification basis

for a product undergoing a change and the current regulations that

would be applicable if a new product was being type certificated. This

acceptance would be based on whether there is a defined safety issue

involved in the specific product

at a good design

does not become unsafe as soon as a new regulation has been published.

Some differences may be acceptable between the certification basis

for a product undergoing a change and the current regulations that

would be applicable if a new product was being type certificated. This

acceptance would be based on whether there is a defined safety issue

involved in the specific product.

The FAA is already encouraging applicants of certain type

certificated products undergoing alterations to comply with later

amendments of the airworthiness standards. By this rulemaking, the FAA

proposes to require all proposed changes for all type certificated

products to comply with later amendments of the airworthiness

standards. The long term result of this approach will be that an

amended type certificate will have a certification basis that provides

a similar level of safety to that provided by the certification basis

of a new type certificate for the same product.

The FAA will issue an advisory circular based on this rulemaking.

This advisory circular will provide guidance on determining the

certification basis for changed aeronautical products, including

identifying the conditions under which it will be necessary to apply

for a new type certificate. By separate notice, in this issue of the

Federal Register, the FAA is also inviting interested persons to

comment on the proposed advisory circular. The FAA will consider

comments from this notice and comments received on the advisory

circular before taking any final action on either.

Discussion of the Proposed Rulemaking

Sections 11.11, 21.19, 21.101, 21.115, and 25.2 would be amended as

follows to implement the policy discussed above in relation to changes

to products:

Section 11.11

sons to

comment on the proposed advisory circular. The FAA will consider

comments from this notice and comments received on the advisory

circular before taking any final action on either.

Discussion of the Proposed Rulemaking

Sections 11.11, 21.19, 21.101, 21.115, and 25.2 would be amended as

follows to implement the policy discussed above in relation to changes

to products:

Section 11.11

Current Sec. 11.11 lists special conditions required as prescribed

under Sec. 21.101(b)(2) as an FAA record that is maintained in current

docket form in the Office of the Chief Counsel. To remain consistent

with the proposed changes to Sec. 21.101, described later, it is

necessary to amend Sec. 11.11 to refer to Sec. 21.101(c) instead of

Sec. 21.101(b)(2). This would not be a substantive change.

Section 21.19

Current Sec. 21.19(a) states that any person who proposes to change

a product must make a new application for a type certificate if the

Administrator finds that the proposed change in design, configuration,

power, power limitation (engines), speed limitations (engines), or

weight is so extensive that a substantially complete investigation of

compliance with the applicable regulations is required. This sentence

has caused confusion because it covers several types of changes for all

products--airplanes, rotorcraft, aircraft engines, and propellers. In

addition, current paragraph (b), (c), and (d) list other specific types

of changes that mandate a new application for a type certificate. Only

the general language of current paragraph (a) would be incorporated

into the new Sec. 21.19, while the previously listed specific changes

would be subject to case-specific evaluations to determine whether they

are substantial. Application of Sec. 21.19 would depend upon an

evaluation of whether the proposed change in ``design, power, thrust,

or weight'' would necessitate a substantially complete investigation of

the compliance of the changed product

rporated

into the new Sec. 21.19, while the previously listed specific changes

would be subject to case-specific evaluations to determine whether they

are substantial. Application of Sec. 21.19 would depend upon an

evaluation of whether the proposed change in ``design, power, thrust,

or weight'' would necessitate a substantially complete investigation of

the compliance of the changed product. Each of the following airplane

design changes, considered alone, could typically be regarded as

substantial design change:

(1) Change from a high wing to a low wing airplane, or vice versa;

(2) Change of empennage configuration for larger airplanes

(cruciform vs `T' or `V' tail);

(3) Complete repositioning of engines (tail to wing, etc.); and

(4) An increase in airplane design complexity resulting from an

increase in the number of engines.

Currently Sec. 21.19(b) describes specific changes for which the

applicant must apply for a new aircraft type certificate. These include

(1) changes in the number of engines or rotors; and (2) changes to

engines or rotors using different principles of propulsion or to rotors

using different principles of operation. Historically, these types of

changes have fallen into one of two categories--those that were not

extensive enough to require a new application for a type certificate,

as evidenced by the large number of exemptions that have been granted

over the past quarter century, or those that were so extensive that a

new application was required because a complete investigation of

compliance is required. Accordingly, the provisions of current

Sec. 21.19(b) are not needed and are not included in this proposal. The

exemptions that have been granted from current Sec. 21.19(b) have

typically required that those areas, systems, components, equipment,

and appliances that are changed or significantly affected by the change

must comply with the applicable regulations in effect at the date of

the application for that change

ons of current

Sec. 21.19(b) are not needed and are not included in this proposal. The

exemptions that have been granted from current Sec. 21.19(b) have

typically required that those areas, systems, components, equipment,

and appliances that are changed or significantly affected by the change

must comply with the applicable regulations in effect at the date of

the application for that change. This requirement would be embodied in

proposed Sec. 21.101, which would generally require that an applicant

for a change to a type certificate must comply with the regulations in

effect at the date of the application for that change, with an

exception, however, that those areas, systems, components, equipment,

and appliances not affected by the change could continue to comply with

the regulations incorporated in the reference type certification basis.

Accordingly, this proposed amendment would be consistent with the

exemptions that have been granted on changes in the number of engines.

The need for requiring a new application for a type certificate would

be alleviated in many instances by the proposed changes to Sec. 21.101.

Current Sec. 21.19(c) describes another specific change in which

the applicant must apply for a new aircraft engine type certificate.

This change is in the principle of operation. Also, current

Sec. 21.19(d) describes specific changes in which the applicant must

apply for a new propeller type certificate. These changes are in the

number of blades or principle of pitch change operation. Invariably,

the type of changes set forth in both of these sections are so

extensive that a new application would be required in any event because

a

ge is in the principle of operation. Also, current

Sec. 21.19(d) describes specific changes in which the applicant must

apply for a new propeller type certificate. These changes are in the

number of blades or principle of pitch change operation. Invariably,

the type of changes set forth in both of these sections are so

extensive that a new application would be required in any event because

a

complete investigation of compliance is required. Accordingly, this

proposal would delete these types of changes from Sec. 21.19. Under

proposed Sec. 21.101, with certain exceptions, these types of changes

and all areas, systems, components, equipment, and appliances affected

by the changes would have to comply with the regulations in effect at

the date of application for the change to the type certificate.

Section 21.101

Current Sec. 21.101(a) states that if a person applies for a change

in a type certificate, the product must comply with either the

regulations referenced in the type certificate or the applicable

regulations in effect at the date of the application for the change, if

elected by the applicant, plus any other amendments the Administrator

finds to be directly related.

Current paragraph (b) addresses novel or unusual design features

where the Administrator finds that the regulations incorporated by

reference in the type certificate do not provide adequate standards. In

this case the applicant must comply with the regulations in effect at

the date of the application for the change and any necessary special

conditions ``to provide a level of safety equal to that established by

the regulations incorporated by reference in the type certificate for

the product.'' This means that the level of safety must be at least

equal to the level of safety that was required by the regulations

referenced in the type certificate.

To ensure that the products meet the latest airworthiness standards

wherever practicable, proposed Sec

vide a level of safety equal to that established by

the regulations incorporated by reference in the type certificate for

the product.'' This means that the level of safety must be at least

equal to the level of safety that was required by the regulations

referenced in the type certificate.

To ensure that the products meet the latest airworthiness standards

wherever practicable, proposed Sec. 21.101 would specify that, with

certain exceptions, the applicant for a change must comply with the

applicable regulations in effect at the date of the application for the

change. The intent of this proposal is to apply the applicable

regulations in effect at the date of the application to those areas,

systems, components, equipment, and appliances affected by the change.

For those areas, systems, components, equipment, and appliances not

affected by the change, continued compliance with the regulations

incorporated by reference in the type certificate is considered

acceptable.

Section 21.101(a)

This proposed paragraph would require an applicant for a change to

a type certificate to comply with the applicable regulations in effect

at the date of the application for the change, also referred to as the

later regulations, and with parts 34 and 36.

Section 21.101(b)

This proposed paragraph would provide exceptions to the regulation

in proposed paragraph (a), permitting the applicant to comply with

earlier amendments to the regulations. A ``regulation'' as used herein

means individual paragraphs of the Federal Aviation Regulations or

predecessor regulations. When choosing the amendment level of a

regulation, all related regulations associated with that amendment

level would have to be included. The amendment level chosen would not

be allowed to predate either the existing basis or anything required by

the retroactive sections, Secs. 23.2, 25.2, 27.2, or 29.2

ans individual paragraphs of the Federal Aviation Regulations or

predecessor regulations. When choosing the amendment level of a

regulation, all related regulations associated with that amendment

level would have to be included. The amendment level chosen would not

be allowed to predate either the existing basis or anything required by

the retroactive sections, Secs. 23.2, 25.2, 27.2, or 29.2. Design

changes vary in both complexity and magnitude so it is necessary for

each proposed change to be evaluated on a case by case basis, taking

into account previous changes and their certification basis. Individual

incremental changes may be modest; however, the cumulative effect can

result in a significant overall change. In this context, the following

factors should be considered: (1) the extent of the previous changes

and the extent to which later amendments have been addressed for these

individual changes; and (2) the extent of revisions to the

airworthiness standards from those of the original certification basis

of the model being changed. When an essentially new product is

developed, step by step, through a series of non-substantial design

changes, it should achieve a level of safety similar to that of a

comparable new product.

Substantial changes are addressed in Sec. 21.19. Those that are not

substantial will be either nonsignificant or significant. A small

weight increase or the installation of a flight management system is an

example of a non-significant change. The installation of a cargo door

is an example of a significant change. A change from a low wing to a

high wing is an example of a substantial change.

In evaluating a design and making the final determination of

nonsignificant or significant, under the exceptions provided for in

Sec. 21.101(b), the FAA would rely on documented engineering, safety,

and economic data

a non-significant change. The installation of a cargo door

is an example of a significant change. A change from a low wing to a

high wing is an example of a substantial change.

In evaluating a design and making the final determination of

nonsignificant or significant, under the exceptions provided for in

Sec. 21.101(b), the FAA would rely on documented engineering, safety,

and economic data. Any data submitted by the applicant should have the

same degree of thoroughness and engineering quality expected for

initial compliance with airworthiness standards.

Section 21.101(b)(1)

This proposed paragraph would provide the first exception to the

regulation in proposed paragraph (a), to show compliance with the later

applicable regulations. The proposed paragraph would state that the

applicant would be allowed to demonstrate compliance with earlier

regulations, but not earlier than the regulations incorporated in the

existing certification basis, if the effect of the proposed change is

not significant, taking into account earlier design changes and

previous updating of the type certification basis.

There may be concurrent significant and non-significant changes

made to a product. For example, there may be a small change in the

model of engines used at the same time large changes are made to the

airframe. Each part of the total change would be evaluated to determine

its significance on its own merit. It must be recognized, however, that

a number of related non-significant changes may collectively represent

a significant change to the product.

Section 21.101(b)(2)

This proposed paragraph would provide the second exception to the

regulation in proposed paragraph (a), to show compliance with the later

applicable regulations. The proposed paragraph would state that the

applicant may show compliance with earlier regulations for those areas,

systems, components, equipment, and appliances that are not affected by

the change

the product.

Section 21.101(b)(2)

This proposed paragraph would provide the second exception to the

regulation in proposed paragraph (a), to show compliance with the later

applicable regulations. The proposed paragraph would state that the

applicant may show compliance with earlier regulations for those areas,

systems, components, equipment, and appliances that are not affected by

the change.

The FAA recognizes that arbitrarily requiring compliance with later

regulations in areas, systems, components, equipment, and appliances

not affected by the change may cause redesign of components that have

an acceptable service record without an attendant improvement in

safety, or may have the counterproductive effect of discouraging any

changes at all, including those that would provide a notable

improvement in safety.

Section 21.101(b)(3)

This proposed paragraph would provide the third exception to the

regulation in proposed paragraph (a) to show compliance with the later

applicable regulations. If compliance with a regulation in effect at

the date of the application for the change would not contribute

materially to the level of safety of the product to be changed, or

would be impractical, the applicant may demonstrate compliance with an

earlier amendment of a regulation provided that the amended regulation

does not precede either the corresponding regulation in Secs. 23.2,

25.2, 27.2, or 29.2 of this chapter, or the corresponding regulation

incorporated by reference in the type certificate.

Compliance with the later amendment would be considered to ``not

materially

practical, the applicant may demonstrate compliance with an

earlier amendment of a regulation provided that the amended regulation

does not precede either the corresponding regulation in Secs. 23.2,

25.2, 27.2, or 29.2 of this chapter, or the corresponding regulation

incorporated by reference in the type certificate.

Compliance with the later amendment would be considered to ``not

materially

contribute to the level of safety'' if the level of safety achieved by

the existing design with the proposed design change would not be

enhanced by compliance with that later amendment. In demonstrating

this, the applicant would show that the level of safety achieved by the

existing design incorporating the proposed design change would achieve

a safety level similar to that reflected in the later amendment.

The factors that would be considered in comparing the level of

safety achieved by the existing design incorporating the proposed

design change with the level of safety achieved by compliance with the

later amendment would include: whether the product has compensating

design features; the extent that the service experience of the product

shows that the operational performance and reliability of the product

provides a level of safety similar to that of later amendments; and

whether compliance with a later amendment, notably when it necessitates

a redesign, would have an adverse effect on safety in terms of

operational performance and reliability.

Nothing would limit the future operation or transfer of a product

after a design change is approved with an older certification basis;

furthermore, the intent of this proposal is to establish certification

bases appropriate to the designs of the products and the designs of the

changes. Therefore, if an applicant for a design change is changing one

or two items of a product, and another applicant is making the same

change to 100 items of the same product, the applicant's design changes

should be certificated to the same basis

furthermore, the intent of this proposal is to establish certification

bases appropriate to the designs of the products and the designs of the

changes. Therefore, if an applicant for a design change is changing one

or two items of a product, and another applicant is making the same

change to 100 items of the same product, the applicant's design changes

should be certificated to the same basis.

Demonstrating that compliance with later regulations would not

materially contribute to the level of safety could necessitate analyses

of the safety features of the existing design and the proposed change,

and an analysis of the safety concerns addressed by the relevant

amendment. The evaluation may be accomplished using a numerical-

statistical approach, subject to the availability and relevance of

applicable data. In practice, engineering judgment, based on

scientific, rational, and reasoned analysis of the relevant data, would

be used in the development of this evaluation. The essentials of the

evaluation would involve:

a. A clear understanding of the regulatory change and what prompted

the change;

b. A detailed knowledge of the proposed design feature; and

c. A comprehensive review of the applicable service experience.

An applicant may be unable to show that compliance with the

original certification basis, together with the level of safety

demonstrated by the applicable service experience, provides a level of

safety similar to that of the later airworthiness regulations. If

compliance with the later airworthiness regulations would then involve

a design change, the benefits of such a redesign would be considered in

the light of any possible adverse effects of the redesign on safety

cation basis, together with the level of safety

demonstrated by the applicable service experience, provides a level of

safety similar to that of the later airworthiness regulations. If

compliance with the later airworthiness regulations would then involve

a design change, the benefits of such a redesign would be considered in

the light of any possible adverse effects of the redesign on safety.

An applicant for a change to a type certificate would not be

required to demonstrate that the changed product complies with a later

amendment to an airworthiness standard if the applicant shows that such

compliance would be ``impractical.'' Compliance with a later amendment

would be considered ``impractical'' when the applicant can establish

that the cost of the design change and related changes necessary to

demonstrate compliance with the amendment would not be commensurate

with the resultant safety benefit. Where compliance with the later

amendment would prompt a redesign, the cost of redesigning other parts

of the product to accommodate this redesign also would be considered.

The FAA continually weighs the desire for the maximum level of

safety with the cost to the manufacturers, operators, and traveling

public for achieving that level of safety. If the designer of an

aircraft in development is tasked with incorporating a ``change'' to a

system in that new design, the designer usually has many more options

in making ``changes'' to related systems to accommodate the ``change.''

Conversely, the systems related to a system to be changed in a

certificated design have been established, and there may be few such

options, if any. These restraints are exacerbated by a change in the

certification basis, and the consideration of the service experience of

the product. Under these conditions, it may become unreasonably costly

for the change to comply with the latest standards

Conversely, the systems related to a system to be changed in a

certificated design have been established, and there may be few such

options, if any. These restraints are exacerbated by a change in the

certification basis, and the consideration of the service experience of

the product. Under these conditions, it may become unreasonably costly

for the change to comply with the latest standards.

A safety benefit-resource evaluation could be used to assist in

determining impracticality, and would be discussed between the

applicant and the Administrator while establishing the certification

basis. The economic issues associated with compliance with the later

amended airworthiness standards would be a major portion of this

evaluation.

Any safety benefit-resource evaluation used to determine

``impractical'' should evaluate the enhancement of the safety involved

with complying with the airworthiness regulation under consideration

along with the cost associated with this compliance. This evaluation

would weigh the factors associated with the safety benefit and the

factors associated with the cost of compliance.

The factors involved with the safety issue could include

seriousness of the consequences of the hazard that the regulatory

change addresses, frequency, of those consequences, and the

effectiveness of applying the regulatory change to the changed product.

The factors involved with the cost of compliance could include labor,

new capital equipment needed, materials, operating cost increase, and

revenue loss. The agency is seeking comments on this concept of using

``Impractical'' as defined herein.

Associated Advisory Circular

The proposed associated advisory circular includes guidance for

purposes of complying with the requirements of this proposed rule. This

advisory circular also contains a safety benefit-resources evaluation

guide, which was recommended by the ARAC to be an acceptable means of

compliance with the exceptions of proposed Sec. 21.101(b)

Impractical'' as defined herein.

Associated Advisory Circular

The proposed associated advisory circular includes guidance for

purposes of complying with the requirements of this proposed rule. This

advisory circular also contains a safety benefit-resources evaluation

guide, which was recommended by the ARAC to be an acceptable means of

compliance with the exceptions of proposed Sec. 21.101(b). As elsewhere

in this edition of the Federal Register, the safety benefit-resource

evaluation guide has been included in the draft advisory circular for

purposes of information only. The safety benefit-resource guide does

describe some of the kinds of issues that the applicant would address,

and the FAA would consider, in determining the certification basis in

accordance with this proposed rule.

Section 21.101(c)

This proposed paragraph would contain the provisions of current

Sec. 21.101(b)(2) concerning special conditions. For consistency with

the other proposed changes to Sec. 21.101, this paragraph would state

that an applicant for a change must comply with any special conditions,

and amendments to those special conditions, if needed, that would

provide a level of safety equal to that established by the regulations

in effect at the date of the application for the change. The

interpretation of ``novel or unusual design features'' shall be the

same as present practice under current Sec. 21.101(b)(2). The

provisions of current Sec. 21.101(b)(1), concerning the use of later

regulations when the regulations incorporated by reference do not

provide adequate standards with respect to the proposed change, would

no longer be needed and would not be incorporated into the proposed

regulation. This is because proposed Sec. 21.101(a) would require the

use of later regulations.

nt Sec. 21.101(b)(2). The

provisions of current Sec. 21.101(b)(1), concerning the use of later

regulations when the regulations incorporated by reference do not

provide adequate standards with respect to the proposed change, would

no longer be needed and would not be incorporated into the proposed

regulation. This is because proposed Sec. 21.101(a) would require the

use of later regulations.

The provisions of current Sec. 21.101(c), concerning the

replacement of reciprocating engines with turbopropeller engines, are

not incorporated into the proposed regulation. A change of this nature

would be considered a significant change, and compliance with the

regulations in effect at the date of application for the change,

therefore, would be required.

Section 21.101(d)

This proposed paragraph would state that an application for a

change to a type certificate for a transport category aircraft would be

effective for 5 years, and an application for a change to a type

certificate for all other products would be effective for 3 years.

These proposed effectivity periods for an application are the same as

those in current Sec. 21.17 (c) and (d) for an application for a type

certificate. Because current Sec. 21.101 requires compliance with the

regulations incorporated by reference in the type certificate and

because the certification basis of the original product doesn't change,

having an effectivity period for an application for a design change has

not been necessary. Under the proposed Sec. 21.101, which would require

meeting the airworthiness standards in effect at the date of the

application for the change, it is necessary to limit the effectivity of

the application for a change, to support the intent of the proposed

regulation. This proposed section would state that if an application

for a design change expires, an applicant may file a new application or

apply for an extension of the original application as in present

Sec. 21.17 (c) and (d)

effect at the date of the

application for the change, it is necessary to limit the effectivity of

the application for a change, to support the intent of the proposed

regulation. This proposed section would state that if an application

for a design change expires, an applicant may file a new application or

apply for an extension of the original application as in present

Sec. 21.17 (c) and (d).

Section 21.101(e)

This proposed paragraph would contain procedures that would be

applicable for changes of aircraft, aircraft engines, and propellers

that have been type certificated using the airworthiness standards

listed in Chapter 1. Proposed paragraph (e)(1) of Sec. 21.101 would

mandate that the certification basis for a change to a product

certificated under the applicable regulations that preceded parts 23,

25, 27, 29, 31, 33, or 35 would be established in the same manner as a

change to a product certificated under one of these parts. For example,

an applicant would be required to show compliance with the latest

amendment(s) under part 23 that would apply to a change to a small

airplane originally certificated under Part 3 of the Civil Air

Regulations (CAR 3). A change to an airplane type certificated under

Special Federal Aviation Regulation No. 41 (SFAR 41), would be handled

somewhat differently. The SFAR 41 requirements incorporated by

reference in the type certificate of such an airplane have expired, and

may no longer be used for purposes of issuing certificates;

accordingly, under proposed Sec. 21.101, only the latest amendments of

the part 23 requirements of the SFAR 41 certification basis would be

applicable for a change to an SFAR 41 airplane design.

Applicability of this proposed regulation would include changes to

products type certificated under Secs. 21.21 and 21.29. In addition,

these proposed procedures would be applicable for changes of aircraft

that have been type certificated under Secs

latest amendments of

the part 23 requirements of the SFAR 41 certification basis would be

applicable for a change to an SFAR 41 airplane design.

Applicability of this proposed regulation would include changes to

products type certificated under Secs. 21.21 and 21.29. In addition,

these proposed procedures would be applicable for changes of aircraft

that have been type certificated under Secs. 21.24, 21.25, 21.27, and

special classes of aircraft, where a part of the certification basis

contains regulations from the airworthiness standards listed in Chapter

1.

At first glance, because some of the certification basis of

aircraft type certificated under Secs. 21.24, 21.25, 21.27, and special

classes of aircraft do not completely consist of airworthiness

standards of the Federal Aviation Regulations, aircraft type

certificated under these regulations may not appear to completely

benefit from the procedures of this proposed rulemaking. However, after

careful consideration, the FAA has determined that the level of safety

of changes to an aircraft that has been type certificated under any of

these regulations, would benefit from the enhanced safety associated

with the appropriate later amendments of those portions of the

airworthiness standards that are a part of the certification basis.

This takes into consideration that the certification basis, in some

cases, may consist of airworthiness standards as well as other

requirements found by the Administrator to be necessary to provide an

equivalent level of safety.

For example, the certification basis for a special class aircraft

or primary category aircraft may be based, in part, on portions of

those airworthiness standards contained in Chapter 1 that were found by

the Administrator to be appropriate for the specific type design

standards as well as other

requirements found by the Administrator to be necessary to provide an

equivalent level of safety.

For example, the certification basis for a special class aircraft

or primary category aircraft may be based, in part, on portions of

those airworthiness standards contained in Chapter 1 that were found by

the Administrator to be appropriate for the specific type design. Since

revisions are frequently made to the airworthiness standards to upgrade

the minimum level of safety required for civilian aircraft and to

incorporate certification standards for modern-state-of-the-art

technology, it seems logical that the level of safety of changes to

special class aircraft would benefit from compliance with the later

airworthiness standards. These proposed procedures would apply only to

those parts of the certification basis that were obtained from the

airworthiness standards listed in Chapter 1.

Joint Aviation Requirements, JAR 22, is a published regulation

being used as a means of compliance by the FAA for gliders, as a

special class of aircraft, but this regulation is not listed in Chapter

1; therefore, the proposed procedures would not be applicable in this

case. Although these procedures are not intended to be applicable to

the Joint Aviation Requirements, an applicant may comply with thee

procedures when the Administrator finds them acceptable for a specific

application.

Surplus military aircraft, type certificated in the restricted

category under Sec. 21.25(a)(2), normally are accepted on the basis of

the previous military qualifications acceptance and service record in

lieu of showing compliance with airworthiness standards in Chapter 1.

However, a change to these aircraft for a special purpose operation

usually is not supported by the military service history and needs to

comply with an airworthiness standard

tricted

category under Sec. 21.25(a)(2), normally are accepted on the basis of

the previous military qualifications acceptance and service record in

lieu of showing compliance with airworthiness standards in Chapter 1.

However, a change to these aircraft for a special purpose operation

usually is not supported by the military service history and needs to

comply with an airworthiness standard. Compliance with the later

amended airworthiness standard for the change would not be appropriate

as the aircraft did not meet an airworthiness standard initially.

Limited category aircraft are surplus military aircraft, mostly

from World War II, that were type certificated under Part 9 of the

Civil Air Regulations for use other than air transport. These aircraft

were not intended to carry persons or property for compensation or

hire, and normally were accepted on the basis of their previous

military qualifications acceptance and service record. However, a

change to these aircraft usually is not supported by the military

service history, therefore, the change must comply with appropriate

airworthiness standards. It seems logical that the level of safety of

changes to aircraft that have not been type certificated to an

airworthiness standard would not benefit from compliance with the later

airworthiness standards.

Section 21.115

The type certificate holder may obtain approval for a change either

by amending the type certificate under Sec. 21.101 or by obtaining a

supplemental type certificate under Sec. 21.115. Any other modifier

would have to obtain a supplemental type certificate under Sec. 21.115.

There should not be a difference in the certification basis for a

change to a type certificated product between these two methods of

approval, amended type certificate or supplemental type certificate.

Current Sec. 21.115 incorporates the provisions of current

Sec. 21.101(a) and (b)

under Sec. 21.115. Any other modifier

would have to obtain a supplemental type certificate under Sec. 21.115.

There should not be a difference in the certification basis for a

change to a type certificated product between these two methods of

approval, amended type certificate or supplemental type certificate.

Current Sec. 21.115 incorporates the provisions of current

Sec. 21.101(a) and (b)

by reference, making the provisions of the latter section equally

applicable to applicants for supplemental type certificates. In view of

the proposed changes to Sec. 21.101, it is necessary to amend

Sec. 21.115 to refer simply to Sec. 21.101 rather than specifically to

Sec. 21.101(a) and (b). This would not be a substantive change.

Section 25.2

Current Sec. 25.2(c) incorporates the provisions of current

Secs. 21.101(a)(2) and (b) by reference, addressing the subsequent

revisions to the special retroactive regulations. To remain consistent

with the proposed changes to Sec. 21.101, it is necessary to amend

Sec. 25.2(c) to refer to Sec. 21.101(a). This would not be a

substantive change.

Paperwork Reduction Act

In accordance with the Paperwork Reduction Act of 1980 (Pub. L. 96-

511), there are no requirements for information collection associated

with this proposed rule.

International Compatibility

The proposal results, primarily, from a recommendation harmonized

with the aviation authorities of Canada and Europe. Similar

corresponding changes to regulations governing type certification

procedures for changed products are being proposed by Transport Canada

and the Joint Aviation Authorities.

Regulatory Evaluation, Regulatory Flexibility Determination, and Trade

Impact Assessment

lity

The proposal results, primarily, from a recommendation harmonized

with the aviation authorities of Canada and Europe. Similar

corresponding changes to regulations governing type certification

procedures for changed products are being proposed by Transport Canada

and the Joint Aviation Authorities.

Regulatory Evaluation, Regulatory Flexibility Determination, and Trade

Impact Assessment

Changes to federal regulations must undergo several economic

analyses. First, Executive Order 12866 directs Federal agencies to

promulgate new regulations or modify existing regulations only if the

potential benefits to society outweigh the potential costs. Second, the

Regulatory Flexibility Act of 1980 requires agencies to analyze the

economic impact of regulatory changes on small entities. Finally, the

Office of Management and Budget directs agencies to assess the effects

of regulatory changes on international trade. In conducting these

assessments, the FAA has determined that this proposed rule: (1) would

generate benefits exceeding its costs and is not ``significant'' as

defined in Executive Order 12866; (2) would not be ``significant'' as

defined in DOT's Policies and Procedures; (3) would not have a

significant impact on a substantial number of small entities; and (4)

would not restrain international trade. These analyses, available in

the docket, are summarized below.

Regulatory Evaluation Summary

benefits exceeding its costs and is not ``significant'' as

defined in Executive Order 12866; (2) would not be ``significant'' as

defined in DOT's Policies and Procedures; (3) would not have a

significant impact on a substantial number of small entities; and (4)

would not restrain international trade. These analyses, available in

the docket, are summarized below.

Regulatory Evaluation Summary

The following discussion of costs and benefits is provided because

the proposed procedures would be explicitly incorporated into formal

regulations. By administrative policy, the FAA is already urging

designers to show that certain changed products comply with selected

amendments that were adopted after the initial application for type

certification of the base product. It is likely that such

administrative decisions would continue, to some unknown degree for an

unknown proportion of type certificated products, in the absence of the

proposed rule.

The proposed rule would not initiate a specific certification

standard or requirement per se, but instead, would formally alter the

manner in which existing and future standards would be determined to be

applicable. As a result, the FAA can describe, but is not able to

quantify, the costs and benefits of the proposal. A quantification of

the impacts would require a forecast of potential future changes to all

commuter and transport category airplane models; all rotorcraft; and

all other categories of regulated aircraft, aircraft engines, and

propellers. In addition, a quantified evaluation would require a review

of all applicable regulations that have been adopted during the

intervening period after the type certification of the product, plus

engineering appraisals of the intended changes for each product, the

effects of those changes on other systems and components, and the

economics associated with bringing each affected system and component

up to the standards of the intervening regulations

eview

of all applicable regulations that have been adopted during the

intervening period after the type certification of the product, plus

engineering appraisals of the intended changes for each product, the

effects of those changes on other systems and components, and the

economics associated with bringing each affected system and component

up to the standards of the intervening regulations. No reasonably

accurate estimate of these factors can be made.

In addition to the absence of a comprehensive estimate, no examples

of such cost estimates are available for this evaluation. In some

instances, the FAA has urged manufacturers of changed products to

comply with later regulations. In association with these actions,

individual manufacturers of proposed changed products have evaluated

the costs and benefits that would be incurred to meet the pertinent

standards. Due to competitive economic considerations, however, such

information is considered proprietary and is not available.

The attributable costs of this proposal are the incremental costs

that would be incurred to meet any additional or more stringent

standards, adopted after the application for type certification of the

initial product, that would not be required in the absence of this

proposal. Similarly, the direct benefit of the proposal is the

augmented safety that would result from meeting such standards.

Although the attributable costs and benefits cannot actually be

quantified, the proposed rule is premised on an analysis to verify that

any actions taken pursuant to it would be cost beneficial

of the

initial product, that would not be required in the absence of this

proposal. Similarly, the direct benefit of the proposal is the

augmented safety that would result from meeting such standards.

Although the attributable costs and benefits cannot actually be

quantified, the proposed rule is premised on an analysis to verify that

any actions taken pursuant to it would be cost beneficial.

As noted in the description of the proposal, compliance with later

regulations would not be required for a change that is not classified

as being significant, for those areas or components not affected by the

change, or where compliance with later regulations would not contribute

materially to the level of safety or would be ``impractical.''

Compliance with later amendments would be considered impractical if the

applicant can show that such compliance would result in costs that are

not consistent with the possible safety benefits. Further guidance on

the definition of what constitutes a significant change would be

provided in an advisory circular.

In addition to the benefits of any individual action taken pursuant

to the proposed rule, the proposal would also generate procedural

benefits. The formalization of this policy by regulation would expedite

decisions about the certification basis of proposed changed products

and, therefore, would provide manufacturers and modifiers with earlier

and more dependable information on which to base their product

development decisions. In addition, the proposed procedures have been

harmonized with the foreign aviation authorities of Canada and Europe

and the resulting common standards would reduce the costs and delays

necessary to formally determine and fulfill dissimilar international

requirements.

Although the attributable costs and benefits of the proposed rule

cannot be quantified, the FAA holds that it would be cost beneficial.

Regulatory Flexibility Determination

rect

effects on the states, on the relationship between the national

government and the states, or on the distribution of power and

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this

proposed would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

Conclusion

For the reasons discussed in the preamble, and based on the

findings in the Regulatory Flexibility Determination and the

International Trade Impact Analysis, the FAA has determined that this

proposed regulation is not a significant regulatory action under

Executive Order 12866. In addition, the FAA certifies that this

proposal, if adopted, will not have a significant economic impact,

positive or negative, on a substantial number of small entities under

the criteria of the Regulatory Flexibility Act. This proposal is

considered nonsignificant under DOT Regulatory Policies and Procedures

(44 FR 11034; February 26, 1979). An initial regulatory evaluation of

the proposal, including a Regulatory Flexibility Determination and

International Trade Impact Analysis, has been placed in the docket. A

copy may be obtained by contacting the person identified under FOR

FURTHER INFORMATION CONTACT.

List of Subjects

14 CFR Part 11

Administrative practice and procedure, Reporting and recordkeeping

requirements.

14 CFR Part 21

Aircraft, Aviation safety, Safety, Type certification

14 CFR Part 25

Aircraft, Aviation safety, Safety, Type certification

The Proposed Amendments

Accordingly, the FAA proposes to amend 14 CFR parts 11, 21, and 25

as follows:

PART 11--GENERAL RULEMAKING PROCEDURES

1. The authority citation for part 11 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40101, 40103, 40105, 40109, 40113,

44110, 44502, 44701--44702, 44711, 46102.

2. The first sentence of Sec. 11.11 is revised to read as follows:

Sec. 11.11 Docket.

Amendments

Accordingly, the FAA proposes to amend 14 CFR parts 11, 21, and 25

as follows:

PART 11--GENERAL RULEMAKING PROCEDURES

1. The authority citation for part 11 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40101, 40103, 40105, 40109, 40113,

44110, 44502, 44701--44702, 44711, 46102.

2. The first sentence of Sec. 11.11 is revised to read as follows:

Sec. 11.11 Docket.

Official FAA records relating to rulemaking actions are maintained

in current docket form in the Office of the Chief Counsel. These

records include: Proposals, notices of proposed rulemaking, written

material received in response to notices, petitions for rulemaking and

exemptions, written material received in response to summaries of

petitions for rulemaking and exemptions, petitions for rehearing or

reconsideration, petitions for modification or revocation, notices

denying petitions for rulemaking, notices granting or denying

exemptions, summaries required to be published under Sec. 11.27,

special conditions required as prescribed under Secs. 21.16 or

21.101(c), written material received in response to published special

conditions, reports of proceedings conducted under Sec. 11.47, notices

denying proposals, and final rules or order. * * *

PART 21--CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS

3. The authority citation for part 21 continues to read as follows:

Authority: 42 U.S.C. 7572; 49 U.S.C. 106(g), 40105, 40113,

44701-44702, 44707, 44709, 44711, 44713, 44715, 45303.

4. Section 21.19 is revised to read as follows:

Sec. 21.19 Changes requiring a new type certificate.

Each person who proposes to change a product must apply for a new

type certificate if the Administrator finds that the proposed change in

design, power, thrust, or weight is so extensive that a substantially

complete investigation of compliance with the applicable regulations is

required.

5. Section 21.101 is revised to read as follows:

Sec. 21.101 Designation of applicable regulations.

e.

Each person who proposes to change a product must apply for a new

type certificate if the Administrator finds that the proposed change in

design, power, thrust, or weight is so extensive that a substantially

complete investigation of compliance with the applicable regulations is

required.

5. Section 21.101 is revised to read as follows:

Sec. 21.101 Designation of applicable regulations.

(a) Except as provided in paragraph (b) of this section, an

applicant for a change to a type certificate must show that the changed

product complies with:

(1) Each regulation in parts 23, 25, 27, 29, 31, 33, and 35 of this

chapter that is applicable to the changed product and that is in effect

at the date of the application for the change; and

(2) Parts 34 and 36 of this chapter.

(b) The applicant may show that the changed product complies with

an earlier amendment of a regulation required by paragraph (a)(1) of

this section, and of any other regulation the Administrator finds is

directly related, provided that the amended regulation does not precede

either the corresponding regulation in Secs. 23.2, 25.2, 27.2, or 29.2

of this chapter, or the corresponding regulation incorporated by

reference in the type certificate:

(1) For a change the effect of which, combined with all previous

relevant changes, the Administrator finds is nonsignificant;

(2) For each area, system, component, equipment, or appliance that

the Administrator finds is not affected by the change; and

(3) For each area, system, component, equipment, or appliance that

is affected by the change, if the Administrator also finds that

compliance with a regulation described in paragraph (a)(1) of this

section would not contribute materially to the level of safety of the

changed product or would be impractical.

uipment, or appliance that

the Administrator finds is not affected by the change; and

(3) For each area, system, component, equipment, or appliance that

is affected by the change, if the Administrator also finds that

compliance with a regulation described in paragraph (a)(1) of this

section would not contribute materially to the level of safety of the

changed product or would be impractical.

(c) If the Administrator finds that the regulations in effect at

the date of the application for the change do not provide adequate

standards with respect to the proposed change because of a novel or

unusual design feature, the applicant must also comply with special

conditions, and amendments to those special conditions, prescribed

under the provisions of Sec. 21.16, to provide a level of safety equal

to that established by the regulations in effect at the date of the

application for the change.

(d) An application for a change to a type certificate for a

transport category aircraft is effective for 5 years, and an

application for a change to any other type certificate is effective for

3 years. If the change has not been approved, or it is clear that it

will not be approved under the time limit established under this

paragraph, the applicant may--

(1) File a new application for a change to the type certificate and

comply with all the provisions of paragraph (a) of this

section applicable to an original application for a change; or

(2) File for an extension of the original application and comply

with the provisions of paragraph (a) of this section for an effective

date of application, to be selected by the applicant, not earlier than

the date that precedes the date of approval of the change by the time

period established under this paragraph for the original application

for the change.

inal application for a change; or

(2) File for an extension of the original application and comply

with the provisions of paragraph (a) of this section for an effective

date of application, to be selected by the applicant, not earlier than

the date that precedes the date of approval of the change by the time

period established under this paragraph for the original application

for the change.

(e) For purposes of this section, ``each regulation that is

applicable to the change'' includes:

(1) Each regulation that is applicable to the change that would

apply to the same change in a product type certificated prior to the

codification of the applicable part(s) of this chapter, if that product

were type certificated at the date of the application for the change;

and

(2) Each regulation that the Administrator found to be appropriate

to a product type certificated under Secs. 21.24, 21.25, or 21.27, or

an aircraft type certificated under Sec. 21.17(b), where the type

certificate incorporated regulations from parts 23, 25, 27, 29, 31, or

35, based on the nature of the product design and the proposed change.

6. Paragraph (a) of 21.115 is revised to read as follows:

Sec. 21.115 Applicable requirements.

(a) Each applicant for a supplemental type certificate must show

that the altered product meets applicable requirements specified in

Sec. 21.101 and, in the case of an acoustical change described in

Sec. 21.93(b), show compliance with the applicable noise requirements

of part 36 of this chapter and, in the case of an emissions change

described in Sec. 21.93(c), show compliance with the applicable fuel

venting and exhaust emissions requirements of part 34 of this chapter.

* * * * *

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

7. The authority citation for part 25 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.

8. Paragraph (c) of Sec. 25.2 is revised to read as follows:

Sec. 25.2 Special retroactive requirements.

* * * * *

le fuel

venting and exhaust emissions requirements of part 34 of this chapter.

* * * * *

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

7. The authority citation for part 25 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.

8. Paragraph (c) of Sec. 25.2 is revised to read as follows:

Sec. 25.2 Special retroactive requirements.

* * * * *

(c) Compliance with subsequent revisions to the sections specified

in paragraph (a) or (b) of this section may be elected or may be

required in accordance with Sec. 21.101(a) of this chapter.

Issued in Washington, DC, on April 22, 1997.

Ava L. Mims,

Acting Director, Aircraft Certification Service.

[FR Doc. 97-11205 Filed 5-1-97; 8:45 am]

BILLING CODE 4910-13-M