Airworthiness Standards; Powerplant Proposals Based on European Joint Aviation Requirements; Proposed Rule DEPARTMENT OF TRANSPORTATION

SUMMARY: This notice proposes changes to the powerplant airworthiness

standards for normal, utility, acrobatic, and commuter category

airplanes. These proposals arise from the joint effort of the Federal

Aviation Administration (FAA) and the European Joint Aviation

Authorities (JAA) to harmonize the Federal Aviation Regulations (FAR)

and the Joint Aviation Requirements (JAR) for airplanes that will be

certificated in these categories. The proposed changes would provide

nearly uniform powerplant airworthiness standards for airplanes

certificated in the United States under 14 CFR part 23 (part 23) and in

the JAA countries under Joint Aviation Requirements 23 (JAR 23)

simplifying airworthiness approvals for import and export purposes.

DATES: Comments must be submitted on or before October 28, 1994.

ADDRESSES: Comments on this notice should be mailed in triplicate to:

Federal Aviation Administration, Office of the Chief Counsel,

Attention: Rules Docket (AGC-200), Docket No. 27804, 800 Independence

Avenue SW., Washington, DC 20591. Comments delivered must be marked

Docket No. 27804. Comments may be inspected in Room 915G weekdays

between 8:30 a.m. and 5:00 p.m., except on Federal holidays.

In addition, the FAA is maintaining a duplicate information docket

of comments in the Office of the Assistant Chief Counsel, ACE-7,

Federal Aviation Administration, Central Region, 601 East 12th Street,

Kansas City, Missouri 64106. Comments in the duplicate information

docket may be inspected in the Office of the Assistant Chief Counsel

weekdays, except Federal holidays, between the hours of 7:30 a.m. and

4:00 p.m.

FOR FURTHER INFORMATION CONTACT:

Norman Vetter, ACE-112, Small Airplane Directorate, Aircraft

Certification Service, Federal Aviation Administration, 601 East 12th

Street, Kansas City, Missouri 64106; telephone (816) 426-5688.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the

proposed rule by submitting such written data, views, or arguments as

they may desire. Comments relating to the environmental, energy, or

economic impact that might result from adopting the proposals in this

notice are also invited. Substantive comments should be accompanied by

cost estimates. Comments should identify the regulatory docket or

notice number and should be submitted in triplicate to the Rules Docket

address specified above. All comments received on or before the

specified closing date for comments will be considered by the

Administrator before taking action on this proposed rulemaking. The

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

received. All comments received will be available, both before and

after the closing date for comments, in the Rules Docket for

examination by interested persons. A report summarizing each FAA-public

contact concerned with the substance of this proposal will be filed in

the docket. Commenters wishing the FAA to acknowledge receipt of their

comments submitted in response to this notice must include a

preaddressed, stamped postcard on which the following statement is

made: ``Comments to Docket No. 27804.'' The postcard will be date

stamped and returned to the commenter.

Availability of NPRM

Any person may obtain a copy of this Notice of Proposed Rulemaking

(NPRM) by submitting a request to the Federal Aviation Administration,

Office of Public Affairs, Attention: Public Inquiry Center, APA-200,

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

267-3484. Communications must identify the notice 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,

which describes the application procedure.

Background

At the June 1990 meeting of the JAA Council (consisting of JAA

members from European countries) and the FAA, the FAA Administrator

committed the FAA to support the harmonization of the FAR with the JAR

being developed for use by the European authorities who are members of

the JAA. In response to this commitment, the FAA Small Airplane

Directorate established an FAA Harmonization Task Force to work with

the JAR 23 Study Group to harmonize part 23 and the proposed JAR 23.

The General Aviation Manufacturers Association (GAMA) also established

a JAR 23/part 23 Committee to provide technical assistance in this

effort.

Following a review of the first draft of proposed JAR 23, members

of the FAA Harmonization Task Force and the GAMA Committee met in

Brussels, Belgium for the October 1990 meeting of the JAR 23 Study

Group. Representatives from the Association Europeenne des

Constructeures de Material Aerospatial (AECMA), an organization of

European airframe manufacturers, also attended. The main agenda item

for this meeting was the establishment of procedures to accomplish

harmonization of the airworthiness standards for normal, utility, and

acrobatic category airplanes. The JAA had decided that its initial

rulemaking effort should be limited to these three categories and that

commuter category airworthiness standards should be addressed

separately.

After that meeting, technical representatives from each of the four

organizations (GAMA, AECMA, FAA and JAA) met to resolve differences

between the proposed JAR and part 23. This portion of the harmonization

effort involved a number of separate meetings of specialists in the

flight, airframe, powerplant, and systems disciplines. These meetings

showed that harmonization would require revisions to both part 23 and

the proposed JAR 23.

Near the end of the effort to harmonize the normal, utility, and

acrobatic category airplane airworthiness standards, the JAA requested

and received recomendations from its member countries on proposed

airworthiness standards for commuter category airplanes. The JAA and

the FAA held specialist and study group meetings to discuss these

recommendations, which resulted in proposals to revise portions of the

part 23 commuter category airworthiness standards.

Unlike the European rules, where commuter category airworthiness

standards are separate, for U.S. rulemaking it is advantageous to adopt

normal, utility, acrobatic, and commuter category airworthiness

standards simultaneously, since commuter category airworthiness

standards are already contained in part 23. Accordingly, this NPRM

proposes to revise the powerplant airworthiness standards for all part

23 airplanes.

During the part 23 Harmonization effort, the FAA established an

Aviation Rulemaking Advisory Committee (ARAC) (56 FR 2190, January 22,

1991), which held its first meeting on May 23, 1991. The ARAC on

General Aviation and Business Airplane (GABA) Issues was established at

that meeting to provide advice and recommendations to the Director,

Aircraft Certification Service, FAA, regarding the airworthiness

standards in part 23 as well as related provisions of parts 91 and 135

of the regulations.

The FAA announced, on June 2-5, 1992, at the JAA/FAA Harmonization

Conference in Toronto, Ontario, Canada, that it would consolidate

within the ARAC structure an ongoing objective to ``harmonize'' the JAR

and the FAR. Coinciding with that announcement, the FAA assigned the

ARAC on GABA Issues those rulemaking projects related to JAR/part 23

harmonization that were in final coordination between the JAA and the

FAA. The harmonization process included the intention to present the

results of JAA/FAA coordination to the public as NPRM's. Subsequently,

the ARAC on GABA Issues established on ARAC-JAR 23 Study Group.

The JAR 23 Study Group made recommendations to the ARAC on GABA

Issues concerning the FAA's disposition of the rulemaking issues

coordinated between the JAA and the FAA. The draft NPRM's previously

prepared by the FAA harmonization team were made available to the

harmonization working group to assist them in their effort.

A notice of the formation of the JAR/FAR 23 Harmonization Working

Group was published on November 30, 1992 (54 FR 56626). The group held

its first meeting on February 2, 1993. These efforts resulted in the

proposals for powerplant airworthiness standards contained in this

notice. The ARAC on GABA Issues agreed with these proposals.

The FAA received unsolicited comments from the JAA dated January

20, 1994, concerning issues that were left unresolved with the JAR 23

Study Group. The JAR/FAR 23 Harmonization Working Group did not address

some of the unresolved issues because the JAA had not yet reached

positions on those issues. Unresolved issues will be dealt with at

future FAR/JAR Harmonization meetings. With respect to other issues

unresolved by the JAR 23 Study Group, the JAR/FAR Harmonization Working

Group recommendations did not reflect harmonization, but reflected the

technical discussion of the merits of each issue that had been

thoroughly debated at the JAR/FAR 23 Harmonization meetings. (The

Working Group Chairperson had been present at the Harmonization

meetings.) The JAA comments have been placed in the docket for this

proposal, and will be considered along with those received during the

comment period.

Following completion of these harmonization efforts, the FAA

determined that the proposed revisions to part 23 were too numerous for

a single NPRM. The FAA decided to simplify the issues by issuing four

NPRM's. These NPRM's address the airworthiness standards in the

specific areas of systems and equipment, powerplant, flight, and

airframe. These NPRM's propose changes in all seven subparts of part

23. Since there is some overlap, interested persons are advised to

review all four NPRM's to identify all proposed changes to a particular

section.

Discussion of the Proposals

Section 23.777 Cockpit Controls

The current requirements of Sec. 23.777 address the location of

powerplant controls on tandem-seated airplanes. For single-engine

airplanes that are designed for a single cockpit occupant, the

powerplant controls should be located in the same position as they are

for tandem-seated airplanes. Therefore, Sec. 23.777(c)(2) would be

revised to include single-seated airplanes.

Section 23.779 Motion and Effect of Cockpit Controls

Current Sec. 23.779(b)(1) provides requirements for ``powerplant

controls,'' including direction of travel and effect. This proposal

would revise Sec. 23.779(b)(1) by adding a new item ``fuel'' to the

table. This proposal would require that any fuel shutoff control other

than mixture must move forward to open.

Section 23.901 Installation

Section 23.901(d)(1), as amended in Amendment 23-43, requires that

each turbine engine installation must be constructed and arranged to

result in vibration characteristics that do not exceed those

established during the type certification of the engine. This

requirement would be revised to add the word ``carcass'' before

vibration. This change would restrict analyses to those vibrations that

are caused by external excitation to the main engine frame or

``carcass.'' While the word ``carcass'' has not traditionally been used

in this context in the United States, it is used in Europe and is

proposed here in the interest of harmonization.

Section 23.901(d)(2), as amended in Amendment 23-43, would be

revised by deleting the last sentence which reads: ``The engine must

accelerate and decelerate safely following stabilized operations under

these rain conditions.'' This requirement is already provided for in

the first sentence of paragraph (d)(2), which states that the turbine

engine must be constructed and arranged to provide ``continued safe

operation.''

Paragraph (e) of this section would be revised by adding the word

``powerplant'' in front of ``installation'' to make clear that it

pertains to all powerplant installations.

Current paragraph (e)(1) would be reformatted to accommodate the

added provisions of new paragraph (e)(1)(ii). The current paragraph

(e)(1) would be divided into paragraphs (e)(1), (e)(1)(i), and

(e)(1)(ii). Paragraph (e)(1) would be revised by adding the word

``installation'' in front of ``instruction'' to make clear which

instructions are applicable. Proposed paragraph (e)(1) would end after

the word ``under--,'' and paragraphs (e)(1)(i) and (e)(1)(ii) would

continue the paragraph.

Proposed paragraph (e)(1)(i) would contain the requirement with

respect to the engine type certificate currently set forth in paragraph

(e)(1). Proposed paragraph (e)(1)(ii) would continue the current

requirement with respect to the propeller type certificate, but also

would permit the alternative of meeting the requirements of another

approved procedure that would provide an equivalent level of safety.

This revision is proposed to be consistent with the proposed revisions

to Sec. 23.905, Propellers, which are discussed below.

Section 23.903 Engines

This proposal would revise paragraphs (c) and (g) by adding the

headings ``Engine isolation'' and ``Restart capability,'' respectively.

Current Sec. 23.903 includes headings for paragraphs (a), (b), (d), (e)

and (f) that identify the subject of each paragraph. This revision will

provide this same identification for paragraphs (c) and (g).

The heading of paragraph (f) would be changed from ``Restart

capability'' to ``Restart envelope'' since the paragraph addresses the

altitude and airspeed envelope for restarting the engines in flight.

Section 23.905 Propellers

Section 23.905(a), which requires each propeller to have a type

certificate, would be revised to require the propeller to either be

type certificated or meet the requirements of another approved

procedure that provides an equivalent level of safety. This would allow

a propeller to be installed and approved on a U.S. type certificated

airplane if that propeller is approved by a procedure that provides a

level of safety equivalent to that provided by the FAA type

certificate. For example, some foreign propellers, approved as part of

the airplane and not having a separate type certificate, could be

approved without requiring an exemption to part 23 or obtaining a U.S.

type certificate; but the ``equivalent procedure'' is not intended to

be limited to a procedure of a foreign authority.

This proposal would provide an alternative approval process for

propellers without reducing safety.

Section 23.906 Propeller Vibration

Current Sec. 23.907(a) requires that each ``propeller with metal

blades or highly stressed metal components must be shown to have

vibration stresses, in normal operating conditions, that do not exceed

values'' that are ``safe for continuous operation.'' The proposed

revision to paragraph (a) would change the applicability to propellers

``other than a conventional fixed-pitch wooden propeller.'' This change

is necessary because all metal and most composite propeller blades are

highly stressed and need to be evaluated for vibration. Only propellers

with fixed-pitch wooden blades would be exempt from the vibration

requirements.

Section 23.925 Propeller Clearance

Current Sec. 23.925 requires that propeller clearance must be

evaluated with the airplane at maximum weight, with the most adverse

center of gravity and with the propeller in the most adverse pitch

position. To make the requirement consistent with current certification

practice, paragraph (a) would be revised to read that propeller

clearance must be evaluated with the airplane at the most adverse

combination of weight and center of gravity, and with the propeller in

the most adverse pitch position.

Interested persons should additionally note that the FAA is also

proposing a change to Sec. 23.925(b). In the Airframe Harmonization

notice, the FAA proposes to move the requirements in Sec. 23.925(b) for

tail wheels, bumpers, and energy absorption devices to Sec. 23.497(c),

Supplementary conditions for tail wheels, where the structural designer

would expect to find such a requirement.

Section 23.929 Engine Installation Ice Protection

This proposal would replace the word ``power'' in Sec. 23.929 in

the phrase ``without appreciable loss of power'' with the word

``thrust.'' The word ``thrust'' is more descriptive of the loss

experienced when ice forms on a propeller.

Section 23.933 Reversing Systems

This proposal would revise Sec. 23.933(a)(1) to agree with the

corresponding turbojet and turbofan reversing system airworthiness

standards of part 25. The purpose of thrust reversing systems for part

23 airplanes is the same as that for part 25 airplanes. While there is

no technical change, in the interest of harmonization part 23 would be

changed to read the same as part 25. Also, this proposal would delete

the word ``forward'' from paragraph (a)(3) since this word is not

necessary. It would correct the typographical error in paragraph (b)(2)

to read ``(b)(1)'' instead of ``(a)(1).''

Section 23.955 Fuel Flow

Section 23.955(a) would be revised by deleting the word ``and''

where it occurs between paragraphs (1), (2), (3) and (4). This is a

nonsubstantive editorial change. All four paragraphs are independent of

each other and equally subordinate to paragraph (a).

Section 23.955(a)(3) would be revised by adding the word

``probable'' so that the requirement would read as follows: ``If there

is a flow meter without a bypass, it must not have any probable failure

mode * * * '' This addition of the word ``probable'' would clarify the

intent of the requirement that only probable failures need be analyzed.

Section 23.959 Unusable Fuel Supply

Current Sec. 23.959 requires that the unusable fuel supply for each

tank be established and states certain parameters for establishing the

unusable supply. The current text of Sec. 23.959 would be redesignated

as paragraph (a); a proposed new paragraph (b) would require that the

effect of any fuel pump failure on the unusable fuel supply also be

established.

It has been industry practice to include in the Airplane Flight

Manual an entry describing any additional unusable fuel quantity that

results from a fuel pump failure. This proposal would not require any

change in the fuel quantity indicator marking required by Sec. 23.1553.

Section 23.963 Fuel Tanks: General

Current Sec. 23.963(b), which requires that each flexible fuel tank

liner must be of an acceptable kind, would be revised by replacing the

phrase ``must be of an acceptable kind'' with the phrase ``must be

shown to be suitable for the particular application.'' The word

``acceptable'' is inexact since all components of a type certificated

airplane must be acceptable. This is a clarifying, nonsubstantive

change. Also the reference to Sec. 23.959 would be revised by changing

it to Sec. 23.959(a) to coincide with the proposed revision of

Sec. 23.959 discussed above.

Section 23.965 Fuel Tank Tests

Section Sec. 23.965(b)(3)(i) would be revised by changing the

phrase ``the test frequency of vibration cycles per minute is obtained

by * * *'' to ``the test frequency of vibration is the number of cycles

per minute obtained by * * *''. This would clarify that it is the

number of cycles per minute that is to be used during testing of a fuel

tank. The frequency of vibration to be used during testing of a fuel

tank on a non-propeller driven airplane has received differing

interpretations during certification procedures.

Section 23.973 Fuel Tank Filler Connection

Current Sec. 23.973(f) specifies a minimum diameter of the fuel

filler opening for airplanes with turbine engines that are not equipped

with pressure fueling systems. The proposed paragraph (f) would remove

the provision related to pressure fueling systems to make the

regulation apply to all airplanes with turbine engines, including

turbine engines that are equipped with pressure fueling systems. The

need to restrict the fuel opening diameter on the top side of the fuel

tank is not related to a function of whether or not the airplane is

equipped with pressure refueling.

Section 23.975 Fuel Tank Vents and Carburetor Vents

Current 23.975(a)(5), as amended in Amendment 23-43, requires that

there be no undrainable points in any vent lines where moisture can

accumulate and that any drain lines installed in the vent lines must

discharge clear of that airplane and be accessible for drainage. This

paragraph would be revised to clarify that there may be no points in

any vent line where moisture can accumulate unless drainage is

provided. The intent is to allow low spots in the fuel tank vent system

if a drain is provided for each low spot.

Section 23.979 Pressure Fueling System

Section 23.979(b) would be revised to add a requirement for

commuter category airplanes that an automatic shutoff means must

provide indication at each fueling station of failure of the shutoff

means to stop fuel flow at the maximum level. This revision makes the

commuter category automatic shutoff means requirements similar to the

requirements for transport category airplanes in Sec. 25.979.

Section 23.1001 Fuel Jettisoning System

This proposal would revise Sec. 23.1001(b)(2) to redefine the speed

at which the fuel jettisoning system tests should be conducted. In a

separate notice, as identified in the background section of this

document, the FAA determined that the best rate-of-climb speed no

longer need be determined under part 23, and has proposed that it be

eliminated from Sec. 23.69(b). Accordingly, this proposal would

redefine the climb speed as stated in Sec. 23.1001(b)(2) to reference

Sec. 23.69(b) as proposed.

Section 23.1013 Oil Tanks

This proposal would delete the word ``crankcase'' in

Sec. 23.1013(d)(1), making this paragraph applicable to all engine

installations.

Section 23.1041 General

Current Sec. 23.1041 under the cooling heading requires that

powerplant and auxiliary power unit cooling provisions must maintain

the temperature of powerplant components and engine fluids within the

limits established for those components and fluids to the maximum

altitude for which approval is requested. This section would be revised

to state ``to the maximum altitude and maximum ambient atmospheric

temperature conditions for which approval is requested.''

For reciprocating engine powered airplanes, it has been the

practice to correct the cooling temperatures to 100 deg.F ambient

temperature. In practice, turbine engine powered airplanes have been

corrected to the maximum temperature for which approval is requested.

The standard would be revised to require all airplanes, regardless of

engine type, to demonstrate adequate cooling at one maximum ambient

atmosphere temperature for which approval is requested.

Section 23.1043 Cooling Tests

Section 23.1043(a)(3) would be revised to shown that the minimum

grade fuel requirement applies to both turbine and reciprocating

engines and that the lean mixture requirement applies to reciprocating

engines only. The introductory text of paragraph (a) would be

simplified by deleting the requirement that compliance must be shown

``under critical ground, water, and flight operating conditions to the

maximum altitude for which approval is requested.'' This requirement is

already contained in Sec. 23.1041.

The requirement in the introductory text of paragraph (a), which

states that, for turbo-charged engines, each turbocharger must be

operated through the part of the climb profile for which turbo-charger

operation is requested, would be moved to paragraph (a)(4) to improve

the organization of the section.

Paragraph (a)(1) would not be substantively changed. It would be

revised to be consistent with proposed changes to Sec. 23.1041 and

changes to the introductory text of paragraph (a) described above.

Paragraph (a)(2) is reworded without substantive change to make

this language identical to the JAR.

Paragraph (a)(3) would be revised to clarify that the requirement

for mixture settings applies to reciprocating engines and that the

mixture settings must be the leanest recommended for the climb. While

this has been the case in practice, it has not been explicitly stated

in the rule. The ``leanest recommended for climb'' mixture setting is

considered a normal operating condition.

Paragraph (a)(5) is removed because water taxi tests are required

by Sec. 23.1041 as amended by Amendment 23-43.

Paragraphs (c) and (d) would be revised by adding the requirement

that cooling correction factors be determined for the appropriate

altitude. This would codify current certification practice and increase

safety by ensuring the proper correction factor is determined.

Section 23.1045 Cooling Test Procedures for Turbine Engine Powered

Airplanes

Current 23.1045(a)(3) requires that compliance with Sec. 23.1041

must be shown by certain specified phases of operations: takeoff,

climb, en route, and landing. It also specifies that the cooling tests

must be conducted with the airplane in the configuration and under the

operating conditions that are critical to cooling for each stage of

flight. It also defines a ``stabilized'' temperature as having a rate

of change of less than 2 deg.F per minute.

Current paragraph (a) would be revised to state more generally that

compliance with Sec. 23.1041 must be shown for all phases of

operations. Also, the airplane must be flown in the configuration, at

the speeds, and following the procedures recommended in the Airplane

Flight Manual for the relative stage of flight that corresponds to the

applicable performance requirements critical to cooling.

The purpose of this proposed revision is to clarify the cooling

test procedures by specifying that all phases of operations, not only

the four phases of flight, are to be evaluated for proper cooling.

Section 23.1047 Cooling Test Procedures for Reciprocating Engine

Powered Airplanes

This proposal would revise the cooling test procedures in

Sec. 23.1047 for reciprocating engine powered airplanes by deleting the

specific procedures. Many of the current provisions in Sec. 23.1047

provide procedures for conducting a cooling test that are inappropriate

in the regulation. Experience has shown that such detailed procedures

are not directly applicable to certain engine configurations and

certain operating conditions. Guidance material is available that

provides appropriate procedures for testing different types of engine

configurations and for testing at different operating conditions.

Section 23.1091 Air Induction System

Current Sec. 23.1091 requires the air induction system design

protect against ingestion of foreign material located ``on the runway,

taxiway, or other airport operating surface.'' This proposal would

require the air induction system design protect against foreign matter,

from whatever source, ``during takeoff, landing, and taxiing.'' This

would codify current certification practice and increase safety by

protecting against universal foreign matter rather than foreign matter

from a restricted source.

Section 23.1093 Induction System Icing Protection

Section 23.1093(c) would be revised by adding the heading

``Reciprocating engines with superchargers.'' This is being done to be

consistent with paragraphs (a) and (b) of this section, which have

headings.

Section 23.1105 Induction System Screens

Current Sec. 23.1105 requires that any induction screens must be

upstream of the carburetor. This requirement would be revised to

include fuel injection systems. Some reciprocating engines incorporate

a fuel injection system, and the same provisions required for a

carburetor are necessary for a fuel injection system.

Section 23.1107 Induction System Filters

Current Sec. 23.1107, which was added in Amendment 23-43, applies

to reciprocating engine installations. The introductory section of this

paragraph would be revised by deleting the reference to reciprocating

engine installations to make the section applicable to airplanes with

either reciprocating or turbine engines. If a filter is installed in

the induction system of a turbine powered airplane, the same provisions

that apply to a reciprocating engine are necessary.

Section 23.1121 General

This proposal would revise Sec. 23.1121(g) by adding standards for

APU exhaust systems; these were overlooked when APU standards were

introduced into part 23 by Amendment 23-43. Prior to Amendment 23-43,

applicants for type certification of part 23 airplanes having APU

installations were required to comply with special conditions for those

installations. Amendment 23-43 included a codification, albeit an

incomplete one, of those special conditions.

Section 23.1141 Powerplant Controls: General

Current Sec. 23.1141(b) requires that each flexible control be of

an acceptable kind. This paragraph would be revised to replace the

phrase ``must be of an acceptable kind'' with the phrase ``must be

shown to be suitable for the particular application.'' This is a

clarifying, non-substantive change.

Section 23.1143 Engine Controls

Current Sec. 23.1143(f) requires that if a power or thrust control

incorporates a fuel shutoff feature, the control must have a means to

prevent the inadvertent movement of the control into the shutoff

position. Paragraph (f) would be revised to add that a fuel control

(other than a mixture control) must also have such a means.

Section 23.1153 Propeller Feathering Controls

Current Sec. 23.1153 requires that if there are propeller

feathering controls, each propeller must have a separate control, and

each control must have a means to prevent inadvertent operation. This

section would be revised because it does not matter whether the

feathering controls are separate from the propeller speed and pitch

controls as long as it is possible to feather each propeller

separately.

Section 23.1181 Designated Fire Zones; Regions Included

Current Sec. 23.1181, which was added in Amendment 23-43, defines

designated fire zones for reciprocating engines and turbine engines.

Proposed new Sec. 23.1181(b)(3) would add to the designated fire zones

for turbine engines any complete powerplant compartments that do not

have firewalls between compressor, accessory, combustor, turbine and

tailpipe sections. The proposal would codify current certification

practice and increase safety by ensuring that all appropriate regions

of turbine engines are evaluated as designated fire zones.

Section 23.1183 Lines, Fittings, and Components

Current Sec. 23.1183(a) includes the requirement that flexible hose

assemblies must be approved. This requirement in paragraph (a) would be

revised by replacing the word ``approved'' with the words ``shown to be

suitable for the particular application.'' The revision clarifies what

is required.

Section 23.1191 Firewalls

Current Sec. 23.1191(a) requires that each engine, auxiliary power

unit, fuel-burning heater, and other combustion equipment intended for

operation in flight must be isolated ``by fire walls, shrouds, or

equivalent means.'' Paragraph (b) of the section requires that each

firewall or shroud must be constructed so that no hazardous quantity of

liquid, gas, or flame can pass from the engine compartment to other

parts of the airplane.

Paragraph (b) would be revised to define isolated compartment and

to show that the provisions of paragraph (b) would also apply to APU's.

Section 23.1203 Fire Detector System

Current Sec. 23.1203(e) requires that wiring and other components

of each fire detector system in an engine compartment must be at least

fire resistant. For accuracy, proposed Sec. 23.1203(e) would replace

the words ``engine compartment'' with ``designated fire zone'' to

correct an oversight in the amendment and to make it consistent with

Sec. 23.1181.

Section 23.1305 Powerplant Instruments

Current Sec. 23.1305(b)(3), as amended in Amendment 23-43,

requires, for reciprocating engine-powered airplanes, a cylinder head

temperature indicator for each air-cooled engine with cowl flaps; each

airplane for which compliance with Sec. 23.1041 is shown at a speed

higher than VY; and each commuter category airplane.

The proposed revision to paragraph (b)(3) would delete paragraph

(b)(3)(ii), which refers to compliance with Sec. 23.1041. The flight

notice referenced above contains a proposal to delete the determination

of the VY speed and this notice proposes a change that the engine

cooling test of Sec. 23.1047 be conducted at a speed recommended in the

Airplane Flight Manual (AFM). Accordingly, other sections referencing

the VY speed or the engine cooling test would also be amended.

The proposed revision would retain the requirement that a cylinder

head temperature indicator is required for commuter category airplanes

having reciprocating engines and for airplanes having air-cooled

engines and cowl flaps.

Section 23.1337 Powerplant Instruments

Under the area of ``Installation,'' the reference in

Sec. 23.1337(b)(1) to Sec. 23.959 would be changed to Sec. 23.959(a),

in accordance with the revision to Sec. 23.959 proposed in this notice.

The revision would redesignate the existing Sec. 23.959 text as

Sec. 23.959(a); there is no change in the requirement itself.

Regulatory Evaluation, Regulatory Flexibility Determination, and Trade

Impact Assessment

Proposed changes to Federal regulations must undergo several

economic analyses. First, Executive Order 12866 directs that each

Federal agency shall propose or adopt a regulation only upon a reasoned

determination that the benefits of the intended regulation justify its

costs. Second, the Regulatory Flexibility Act of 1980 requires agencies

to analyze the economic effect of regulatory changes on small entities.

Third, the Office of Management and Budget directs agencies to assess

the effects of regulatory changes on international trade. In conducting

these analyses, the FAA has determined that this rule: (1) Would

generate benefits that would justify its costs and is not a

``significant regulatory action'' as defined in the Executive Order;

(2) is not ``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 constitute a barrier to international

trade. These analyses, available in the docket, are summarized below.

Regulatory Evaluation Summary

The FAA has determined that the benefits of the proposed rule,

though not directly quantifiable, would exceed the expected costs.

Minor costs, ranging from $240 to $6,000 per certification, are

projected for four of the provisions in this proposal. No costs are

attributed to the other thirty-two provisions. The benefits of the

proposed rule are considered below in four categories: (1)

harmonization, (2) safety, (3) reduced need for special conditions, and

(4) clarification.

Harmonization

The proposed rule, in concert with other rulemaking and policy

actions, would provide nearly uniform powerplant airworthiness

standards for airplanes certificated in the United States and the JAA

member countries. Thirty-four of the thirty-six sections affected by

the proposed rule would be harmonized. The resulting greater uniformity

of standards would simplify airworthiness approval for import and

export purposes and reduce the cost of certification for airplanes

seeking certification under both sets of regulations.

Safety

In addition to the harmonization benefits, five proposed changes

would provide additional safety benefits. First, the proposed rule

would revise Sec. 23.933(a)(1) to more closely agree with the

corresponding turbojet and turbofan reversing system airworthiness

standards of part 25. The FAA estimates that this provision would

necessitate an additional 100 hours of failure mode and effects

analysis at an assumed cost rate of $60 per hour, including labor and

overhead. The estimated $6,000 cost would apply to each certification.

The FAA projects that no additional production or operating costs would

result from this provision.

The primary potential benefit of the provision is the additional

safety that could result from analyzing the feasible range of reverser

system failures, the effects of those failures, and the corresponding

capabilities necessary to correct the failure or circumvent its

effects. Such an analysis would reduce the possibility that an

unanticipated condition with catastrophic potential would remain in the

system. In addition to the safety benefit, it is expected that some

operating benefits and manufacturing economies would result from the

uniformity of standards between parts 23 and 25. The FAA is not able to

quantify the potential benefits of this provision but has determined

that the benefits would exceed the expected minor costs.

Second, the proposed rule would add a new paragraph (b) to

Sec. 23.959 requiring that the effect of any fuel pump failure on the

unusable fuel supply be determined. Though not previously required, it

has been industry practice to include this information in the Airplane

Flight Manual. The FAA estimates that the nominal cost of making this

determination would be $240 per certification (4 hours of engineering

analysis at $60 per hour). In addition, an insignificant cost ($1)

would be incurred in adding a table entry to the manual for each

airplane that is produced. The fact that the proposed requirement is

already standard practice supports the FAA's position that the

potential benefits of the provision would exceed the minor costs. The

safety benefits of this provision would be derived from the assurance

that this vital information would continue to be provided for future

airplane models.

Third, under Sec. 23.979, the proposed rule would add the

requirement for commuter category airplanes that an indication be

provided at each fueling station in the event of a failure of the

shutoff means to stop fuel flow at the maximum level. The FAA estimates

that the proposed required device would necessitate an incremental

design and development cost of $3000 per certification (50 hours of

engineering design at $60 per hour) and an additional nominal

manufacturing cost of $10 per airplane. The benefit of the provision is

the avoidance of a potentially catastrophic condition whereby excess

fuel could unknowingly be forced out of the contained fuel system by

the pressure fueling system. The FAA holds that these potential

benefits would exceed the minor associated costs.

Fourth, Sec. 23.1041 would require that the powerplant cooling

system must be able to maintain the specified operating temperatures of

the powerplant components and fluids. The ambient temperature for

testing reciprocating engine airplanes is currently required to be

corrected to show the capacity of the cooling system at 100 deg.F.

Under the proposal, this temperature standard would be revised to the

``maximum ambient temperature conditions for which approval is

requested.''

No costs are attributed to this provision. Reciprocating engine

airplane manufacturers would continue to have the option to request

approval for operations at the existing 100 deg.F temperature.

A decision to request approval for a higher temperature would

necessitate demonstration of the capability of the cooling system at

that temperature. That choice, however, would be made at the

manufacturer's discretion and would be based on its decision that any

associated incremental cooling system costs would be recovered in the

marketplace. The potential benefit of this provision is the reduced

likelihood that an inadequate cooling system would be relied on during

high temperature operations.

Finally, Sec. 23.1045(a) would be revised to state more generally

that compliance with the cooling margin requirements of Sec. 23.1041

must be shown for all phases of operation, as compared to the four

phases of flight currently listed. In effect, the proposal would add

the taxi phase of operation.

The FAA estimates that the specific addition of the taxi phase

would necessitate an incremental 5 hours of engineering analysis valued

at $60 per hour, for a total of $300 per certification. The potential

benefit of this provision is the enhanced safety that would result from

evaluating the efficacy of the cooling system during the taxi phase of

operation. In the taxi phase of operation, engine power settings and

heat production generally may be lower than that experienced during

flight, but available air circulation might also be lower. The heat

mechanics of the two phases of operation are distinct and warrant

separate evaluation. The FAA holds that the potential benefits of this

provision would exceed the nominal associated costs.

Reduced Need for Special Conditions

The proposed rule includes five provisions that would replace the

need for processing certain parts or materials as special conditions

because they have been considered novel or unusual design features. The

subjects of these provisions include composite propellers, fuel

injection systems for reciprocating engines, induction filters on

turbine engines, fuel shutoff controls other than mixture controls, and

auxiliary power units. No costs are attributed to these provisions.

Formalization of the equivalent safety standards and requirements for

these subjects would obviate the need for special conditions actions

and would simplify the certification process for manufacturers.

Clarification

Several unclear provisions of part 23 were revealed during the

harmonization review. In response to this finding, the proposal

includes a number of no-cost, editorial revisions that would clarify

the existing requirements. These changes would benefit manufacturers by

removing potential confusion about the specific standards and

requirements necessary for product certification.

In summary, the FAA holds that each of the provisions, as well as

the entire proposal, would be cost beneficial.

Regulatory Flexibility Determination

The Regulatory Flexibility Act of 1980 (RFA) was enacted by

Congress to ensure that small entities are not unnecessarily or

disproportionately burdened by Government regulations. The RFA requires

a Regulatory Flexibility Analysis if a proposed rule would have a

significant economic impact, either detrimental or beneficial, on a

substantial number of small entities. Based on implementing FAA Order

2100.14A, Regulatory Flexibility Criteria and Guidance, the FAA has

determined that the proposed amendments would not have a significant

economic impact on a substantial number of small entities.

Trade Impact Assessment

The proposed rule would not constitute a barrier to international

trade, including the export of American airplanes to foreign countries

and the import of foreign airplanes into the United States. Instead,

the proposed powerplant airworthiness standards would be harmonized

with those of foreign aviation authorities and would lessen current

restraints on trade caused by differences in certification

requirements.

Federalism Implications

The regulations proposed herein would not have substantial direct

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

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

Conclusion

The FAA proposes to revise the airworthiness standards to provide

propulsion standards for normal, utility, acrobatic, and commuter

category airplanes to harmonize them with the standards that will be

proposed for the same category airplanes by the Joint Aviation

Authorities in Europe. If adopted, the proposed revisions would reduce

the regulatory burden on the United States and European airplane

manufacturers by relieving them of the need to show compliance with

different standards each time they seek certification approval of an

airplane in a different country.

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

findings in the Regulatory Evaluation, the FAA has determined that this

proposed regulation is not significant 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 not considered significant

under DOT Regulatory Policies and Procedures (44 FR 11034, February 26,

1979). An initial regulatory evaluation of the proposal has been placed

in the docket. A copy may be obtained by contacting the person

identified under FOR FURTHER INFORMATION CONTACT.

List of Subjects in 14 CFR Part 23

Aircraft, Aviation safety, Signs and symbols.

The Proposed Amendment

In consideration of the foregoing, the Federal Aviation

Administration proposes to amend part 23 of the Federal Aviation

Regulations (14 CFR part 23) as follows:

PART 23--AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND

COMMUTER CATEGORY AIRPLANES

1. The authority citation for part 23 continues to read as follows:

Authority: 49 U.S.C. app. 1344, 1354(a), 1355, 1421, 1423, 1425,

1428, 1429, and 1430; 49 U.S.C. 106(g).

Sec. 23.777 [Amended]

2. Section 23.777(c)(2) is amended by adding the words ``single

and'' between the words ``for'' and ``tandem'' in the first sentence.

3. The table in Sec. 23.779(b)(1) is amended by adding a new item

between the items ``mixture'' and ``carburetor air heat or alternate

air'' to read as follows:

Sec. 23.779 Motion and effect of cockpit controls.

* * * * *

(b) * * *

------------------------------------------------------------------------

Motion and effect

------------------------------------------------------------------------

(1) Powerplant controls:

*****

Fuel............................. Forward for open.

*****

------------------------------------------------------------------------

4. Section 23.901 is amended by revising paragraphs (d)(1), (d)(2),

(e) Introductory text and (e)(1) to read as follows:

Sec. 23.901 Installation.

* * * * *

(d) * * *

(1) Result in carcass vibration characteristics that do not exceed

those established during the type certification of the engine.

(2) Provide continued safe operation without a hazardous loss of

power or thrust while being operated in rain for at least three minutes

with the rate of water ingestion being not less than four percent, by

weight, of the engine induction airflow rate at the maximum installed

power or thrust approved for takeoff and at flight idle.

(e) The powerplant installation must comply with--

(1) The installation instructions provided under--

(i) The engine type certificate; and

(ii) The propeller type certificate or the requirements of another

approved procedure that provides an equivalent level of safety.

* * * * *

5. Section 23.903 is amended by adding headings to paragraphs (c)

and (g), and by revising the heading of paragraph (f) to read as

follows:

Sec. 23.903 Engines.

* * * * *

(c) Engine isolation. * * *

* * * * *

(f) Restart envelope. * * *

(g) Restart capability. * * *

Sec. 23.905 [Amended]

6. Section 23.905 is amended by adding the words ``or meet the

requirements of another approved procedure that provides an equivalent

level of safety'' to the end of paragraph (a).

Sec. 23.907 [Amended]

7. Section 23.907(a) introductory text is amended by removing the

words ``with metal blades or highly stressed metal components'' and

replacing them with the words ``other than a conventional fixed-pitch

wooden propeller.''

8. Section 23.925 is amended by revising the introductory text to

read as follows:

Sec. 23.925 Propeller clearance.

Unless smaller clearances are substantiated, propeller clearances,

with the airplane at the most adverse combination of weight and center

of gravity, and with the propeller in the most adverse pitch position,

may not be less than the following:

* * * * *

Sec. 23.929 [Amended]

9. Section 23.929 is amended by removing the word ``power'' and

adding, in its place, the word ``thrust.''

10. Section 23.933 is amended by removing the word ``forward''

where ever it appears in paragraph (a)(3); by revising the reference in

paragraph (b)(2) that reads ``(a)(1)'' to read ``(b)(1)''; and by

revising paragraph (a)(1) to read as follows:

Sec. 23.933 Reversing systems.

(a) * * *

(1) Each system intended for ground operation only must be designed

so that, during any reversal in flight, the engine will produce no more

than flight idle thrust. In addition, it must be shown by analysis or

test, or both, that--

(i) Each operable reverser can be restored to the forward thrust

position; or

(ii) The airplane is capable of continued safe flight and landing

under any possible position of the thrust reverser.

* * * * *

11. Section 23.955 is amended by revising paragraphs (a)(1) through

(a)(4) to read as follows:

Sec. 23.955 Fuel flow.

(a) * * *

(1) The quantity of fuel in the tank may not exceed the amount

established as the unusable fuel supply for that tank under

Sec. 23.959(a) plus that necessary to show compliance with this

section.

(2) If there is a fuel flowmeter, it must be blocked during the

flow test and the fuel must flow through the meter or its bypass.

(3) If there is a flowmeter without a bypass, it must not have any

probable failure mode that would restrict fuel flow below the level

required in this fuel demonstration.

(4) The fuel flow must include that flow needed for vapor return

flow, jet pump drive flow, and for all other purposes for which fuel is

used.

* * * * *

12. Section 23.959 is amended by designating the text of the

section as paragraph (a), and by adding a new paragraph (b) to read as

follows:

Sec. 23.959 Unusable fuel supply.

* * * * *

(b) The effect on the unusable fuel quantity as a result of a

failure of any pump shall be determined.

13. Section 23.963 is amended by revising the reference in

paragraph (e) that reads ``Sec. 23.959'' to read ``Sec. 23.959(a)'' and

by revising paragraph (b) to read as follows:

Sec. 23.963 Fuel tanks: general.

* * * * *

(b) Each flexible fuel tank liner must be shown to be suitable for

the particular application.

* * * * *

14. Section 23.965 is amended by revising paragraph (b)(3)(i) to

read as follows:

Sec. 23.965 Fuel tank tests.

* * * * *

(b) * * *

(3) * * *

(i) If no frequency of vibration resulting from any r.p.m. within

the normal operating range of engine or propeller speeds is critical,

the test frequency of vibration is the number of cycles per minute

obtained by multiplying the maximum continuous propeller speed in

r.p.m. by 0.9 for propeller-driven airplanes, except that for non-

propeller driven airplanes the test frequency of vibration is 2,000

cycles per minute.

* * * * *

15. Section 23.973(f) is revised to read as follows:

Sec. 23.973 Fuel tank filler connection.

* * * * *

(f) For airplanes with turbine engines, the inside diameter of the

fuel filler opening must be no smaller than 2.95 inches.

16. Section 23.975(a)(5) is revised to read as follows:

Sec. 23.975 Fuel tank vents and carburetor vapor vents.

(a) * * *

(5) There may be no point in any vent line where moisture can

accumulate with the airplane in either the ground or level flight

attitudes, unless drainage is provided. Any drain valve installed in

the vent lines must discharge clear of the airplane and be accessible

for drainage;

* * * * *

17. Section 23.979(b) is revised to read as follows:

Sec. 23.979 Pressure fueling systems.

* * * * *

(b) An automatic shutoff means must be provided to prevent the

quantity of fuel in each tank from exceeding the maximum quantity

approved for that tank. This means must--

(1) Allow checking for proper shutoff operation before each fueling

of the tank; and

(2) For commuter category airplanes, indicate at each fueling

station, a failure of the shutoff means to stop the fuel flow at the

maximum quantity approved for that tank.

* * * * *

18. Section 23.1001 is amended by revising paragraph (b)(2) to read

as follows:

* * * * *

Sec. 23.1001 Fuel jettisoning system.

* * * * *

(b) * * *

(2) A climb at the speed at which the one engine inoperative

enroute climb data have been established in accordance with

Sec. 23.69(b), with the critical engine inoperative and the remaining

engines at maximum continuous power; and

* * * * *

Sec. 23.1013 [Amended]

19. Section 23.1013 is amended by removing the word ``crankcase''

in paragraph (d)(1).

Sec. 23.1041 [Amended]

20. Section 23.1041 is amended by adding the phrase ``and maximum

ambient atmospheric temperature conditions'' between the words

``maximum altitude'' and ``for which approval''.

21. Section 23.1043 (a), (c), and (d) are revised to read as

follows:

Sec. 23.1043 Cooling tests.

(a) General. Compliance with Sec. 23.1041 must be shown on the

basis of tests, for which the following apply:

(1) If the tests are conducted under ambient atmospheric

temperature conditions deviating from the maximum for which approval is

requested, the recorded powerplant temperatures must be corrected under

paragraphs (c) and (d) of this section, unless a more rational

correction method is applicable.

(2) No corrected temperature determined under paragraph (a)(1) of

this section may exceed established limits.

(3) The fuel used during the cooling tests must be of the minimum

grade approved for the engine and, for a reciprocating engine, the

mixture settings must be the leanest recommended for climb.

(4) For turbocharged engines, such turbocharger must be operated

through that part of the climb profile for which operation with the

turbocharger is requested.

(b) * * *

(c) Correction factor (except cylinder barrels). Temperatures of

engine fluids and powerplant components (except cylinder barrels) for

which temperature limits are established, must be corrected by adding

to them the difference between the maximum ambient atmospheric

temperature for the relevant altitude for which approval has been

requested and the temperature of the ambient air at the time of the

first occurrence of the maximum fluid or component temperature recorded

during the cooling test.

(d) Correction factor for cylinder barrel temperatures. Cylinder

barrel temperatures must be corrected by adding to them 0.7 times the

difference between the maximum ambient atmospheric temperature for the

relevant altitude for which approval has been requested and the

temperature of the ambient air at the time of the first occurrence of

the maximum cylinder barrel temperature recorded during the cooling

test.

22. Section 23.1045(a) is revised to read as follows:

Sec. 23.1045 Cooling test procedures for turbine engine powered

airplanes.

(a) Compliance with Sec. 23.1041 must be shown for all phases of

operation. The airplane must be flown in the configurations, at the

speeds, and following the procedures recommended in the Airplane Flight

Manual for the relevant stage of flight, and that correspond to the

applicable performance requirements that are critical to cooling.

* * * * *

23. Section 23.1047 is revised to read as follows:

Sec. 23.1047 Cooling test procedures for reciprocating engine powered

airplanes.

Compliance with Sec. 23.1041 must be shown for the climb (or, for

multiengine airplanes with negative one-engine-inoperative rates of

climb, the descent) stage of flight. The airplane must be flown in the

configurations, at the speeds and following the procedures recommended

in the Airplane Flight Manual (AFM), and that correspond to the

applicable performance requirements that are critical to cooling.

24. Section 23.1091 is amended by revising paragraph (c)(2) to read

as follows:

Sec. 23.1091 Air induction system.

* * * * *

(c) * * *

(2) The airplane must be designed to prevent water or slush on the

runway, taxiway, or other airport operating surfaces from being

directed into the engine or auxiliary power unit air intake ducts in

hazardous quantities. The air intake ducts must be located or protected

so as to minimize the ingestion of foreign matter during takeoff,

landing, and taxiing.

Sec. 23.1093 [Amended]

25. Section 23.1093 is amended by adding the heading

``Reciprocating engines with Superchargers'' to paragraph (c).

26. Section 23.1105 is amended by revising paragraph (a) to read as

follows:

Sec. 23.1105 Induction system screens.

* * * * *

(a) Each screen must be upstream of the carburetor or fuel

injection system.

* * * * *

27. Section 23.1107 is amended by revising the introductory text to

read as follows:

* * * * *

Sec. 23.1107 Induction system filters.

If an air filter is used to protect the engine against foreign

material particles in the induction air supply--

* * * * *

28. Section 23.1121(g) is revised to read as follows:

Sec. 23.1121 General.

* * * * *

(g) If significant traps exist, each turbine engine and auxiliary

power unit exhaust system must have drains discharging clear of the

airplane, in any normal ground and flight attitude, to prevent fuel

accumulation after the failure of an attempted engine or auxiliary

power unit start.

* * * * *

29. Section 23.1141(b) is revised to read as follows:

Sec. 23.1141 Powerplant controls: general.

* * * * *

(b) Each flexible control must be shown to be suitable for the

particular application.

* * * * *

30. Section 23.1143(f) is amended by revising the introductory text

to read as follows:

Sec. 23.1143 Engine controls.

* * * * *

(f) If a power or thrust control, or a fuel control (other than a

mixture control) incorporates a fuel shutoff feature, the control must

have a means to prevent the inadvertent movement of control into the

off position. The means must--

* * * * *

31. Section 23.1153 is revised to read as follows:

Sec. 23.1153 Propeller feathering controls.

If there are propeller feathering controls, whether or not they are

separate from the propeller speed and pitch controls, it must be

possible to feather each propeller separately. Each control must have

means to prevent inadvertent operation.

32. Section 23.1181 is amended by adding a new paragraph (b)(3) to

read as follows:

Sec. 23.1181 Designated fire zones; regions included.

* * * * *

(b) * * *

(3) Any complete powerplant compartment in which there is no

isolation between compressor, accessory, combustor, turbine, and

tailpipe sections.

* * * * *

Sec. 23.1183 [Amended]

33. Section 23.1183(a) is amended by removing the word ``approved''

in the next to the last sentence, and replacing it with the words

``shown to be suitable for the particular application.''

34. Section 23.1191 is amended by revising paragraph (b) to read as

follows:

Sec. 23.1191 Firewalls.

* * * * *

(b) Each firewall or shroud must be constructed so that no

hazardous quantity of liquid, gas, or flame can pass from the

compartment created by the firewall or shroud to other parts of the

airplane.

* * * * *

35. Section 23.1203 is amended by revising paragraph (e) to read as

follows:

Sec. 23.1203 Fire detector system.

* * * * *

(e) Wiring and other components of each fire detector system in a

designated fire zone must be at least fire resistant.

* * * * *

Sec. 23.1305 [Amended]

36. Section 23.1305 is amended by removing paragraph (b)(3)(ii) and

redesignating paragraph (b)(3)(iii) as paragraph (b)(3)(ii).

Sec. 23.1337 [Amended]

37. Section 23.1337 is amended by removing the reference to

``Sec. 23.959'' in paragraph (b)(1) and replacing it with

``Sec. 23.959(a)''.

Issued in Washington, DC, on June 22, 1994.

Thomas E. McSweeny,

Director, Aircraft Certification Service.

[FR Doc. 94-15619 Filed 6-29-94; 8:45 am]

BILLING CODE 4910-13-M