Airworthiness Directives; Fokker Model F-27 Mark 100, 200, 300, 400, 500, 600, 700, and 800 Series Airplanes.

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-76-AD]

Airworthiness Directives; Fokker Model F-27 Mark 100, 200, 300,

400, 500, 600, 700, and 800 Series Airplanes.

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of Proposed Rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Fokker Model F-27 series

airplanes. This proposal would require the implementation of a

corrosion prevention and control program either by accomplishing

specific tasks or by revising the maintenance inspection program to

include such a program. This proposal is prompted by reports of

incidents involving corrosion and fatigue cracking in transport

category airplanes that are approaching or have exceeded their economic

design goal; these incidents have jeopardized the airworthiness of the

affected airplanes. The actions specified by the proposed AD are

intended to prevent degradation of the structural capabilities of the

airplane due to the problems associated with corrosion.

DATES: Comments must be received by May 9, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 93-NM-76-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9 a.m. and 3 p.m., Monday through Friday, except Federal

holidays.

The service information referenced in the proposed rule may be

obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street,

Alexandria, Virginia 22314. This information may be examined at the

FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT: Mark Quam, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-2145; fax (206) 227-1320.

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. Communications shall identify the Rules Docket number

and be submitted in triplicate to the address specified above. All

communications received on or before the closing date for comments,

specified above, will be considered before taking action on the

proposed rule. The proposals contained in this notice may be changed in

light of the comments received.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the proposed rule. All

comments submitted 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 Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 93-NM-76-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

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

to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules

Docket No. 93-NM-76-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

In April 1988, a high-cycle transport category airplane

(specifically, a Boeing Model 737) was involved in an accident in which

the airplane suffered major structural damage during flight.

Investigation of this accident revealed that the airplane had numerous

fatigue cracks and a great deal of corrosion. Subsequent inspections

conducted by the operator on other high-cycle transport category

airplanes in its fleet revealed that other airplanes had extensive

fatigue cracking and corrosion.

Prompted by the data gained from this accident, the FAA sponsored a

conference on aging airplanes in June 1988, which was attended by

representatives from the aviation industry and airworthiness

authorities from around the world. It became obvious that, because of

the tremendous increase in air travel, the relatively slow pace of new

airplane production, and the apparent economic feasibility of operating

older technology airplanes rather than retiring them, increased

attention needed to be focused on the aging airplane fleet and

maintaining its continued operational safety.

The Air Transport Association (ATA) of America and the Aerospace

Industries Association (AIA) of America agreed to undertake the task of

identifying and implementing procedures to ensure the continued

structural airworthiness of aging transport category airplanes. An

Airworthiness Assurance Task Force (AATF) was established in August

1988, with members representing aircraft manufacturers, operators,

regulatory authorities, and other aviation industry representatives

worldwide. The objective of the AATF was to sponsor ``Working Groups''

to:

1. Select service bulletins, applicable to each airplane model in

the transport fleet, to be recommended for mandatory modification of

aging airplanes;

2. Develop corrosion-directed inspections and prevention programs;

3. Review the adequacy of each operator's structural maintenance

program;

4. Review and update the Supplemental Inspection Documents (SID);

and

5. Assess repair quality.

The working group assigned to review the Fokker Model F-27 series

airplanes has completed its work on Item (2) and has developed a

baseline program for controlling corrosion problems that may jeopardize

the continued airworthiness of the Model F-27 fleet. The program is

contained in Fokker Document SE-291, ``F-27 Corrosion Control

Program,'' with revisions through October 1, 1993. (Hereafter, this

publication is referred to as ``the Document.'') The

Rijksluchtvaartdienst (RLD), which is the airworthiness authority for

the Netherlands, classified this Document as mandatory and issued

Netherlands Airworthiness Directive (BLA) 91-113, Issue 2, dated June

26, 1992, in order to assure the continued airworthiness of these

airplanes in The Netherlands.

Section 2.1 of the Document defines three levels of corrosion:

Level l corrosion is that which does not exceed certain limits; Level 2

corrosion is that which exceeds those limits; and Level 3 corrosion is

significant corrosion which is potentially an urgent airworthiness

concern.

Sections 2.2 and 2.3 of the Document provide general guidelines to

develop a corrosion prevention and control program. These guidelines

address such things as a baseline program, implementation ages, access

for inspection, repetitive inspection intervals, operating environment,

newly-acquired airplanes, general cleanliness of the airplane, and the

fact that sampling is unreliable in effectively controlling corrosion.

Section 2.4 of the Document sets forth the general implementation

schedule for the corrosion inspection/control program. As described in

that section, each ``aircraft zone'' is assigned an ``Initial

Inspection Time'' and a ``Repeat Inspection Time.'' The program is

applicable to each aircraft zone on all Model F-27 series airplanes

whose age has reached or exceeded the Initial Inspection Time for that

zone. For airplanes that have not reached or exceeded the Initial

Inspection Time of the specific aircraft zone, a particular inspection

task has to be performed before the airplane has reached the Initial

Inspection Time for the specific aircraft zone, or before the Repeat

Inspection Time of the task is exceeded (a maximum of 6 years),

whichever occurs later. For airplanes that have already reached or

exceeded the Initial Inspection Time of the specific aircraft zone, a

particular inspection has to be performed before the Repeat Inspection

Time of the task is exceeded or within 6 years, whichever occurs first.

Section 2.4 of the Document also identifies the specific aircraft

zones that are subject to the program, and describes the ``basic task''

to be accomplished in each defined aircraft zone as part of the

baseline program, along with the initial inspection time and repeat

inspection time for each area, and other information necessary to carry

out the program for each area. The Document defines a ``basic task'' as

including not only the pertinent visual inspections of all primary and

secondary structures, but any necessary repairs, application of

sealants or corrosion inhibitors, and other follow-on procedures, as

well. A basic task may also include detailed visual and non-destructive

inspections (NDI); where NDI's are employed, adequate standards and

procedures must be developed and properly recorded for the area

inspected.

Section 2.5 establishes the procedures for reporting the results of

the inspections conducted under the corrosion prevention and control

program.

Section 2.6 provides for periodic review and update of the data

contained in the Document.

This airplane model is manufactured in the Netherlands and is type

certificated for operation in the United States under the provisions of

Section 21.29 of the Federal Aviation Regulations and the applicable

bilateral airworthiness agreement. Pursuant to this bilateral

airworthiness agreement, the RLD has kept the FAA informed of the

situation described above. The FAA has examined the findings of the

RLD, reviewed all available information, and determined that AD action

is necessary for products of this type design that are certificated for

operation in the United States.

Since corrosion is likely to exist or develop on airplanes of this

type design, an AD is proposed which would require adoption of a

corrosion prevention and control program that is equivalent to or

better than the program specified in the Document previously described.

Operators would be permitted to accomplish this either by performing

the specific basic tasks described in the Document (the ``task-by-task

method''), or by revising their FAA-approved maintenance program to

include such a program.

Paragraph (a) of the proposal sets forth the proposed compliance

times for the initial basic task of each affected aircraft zone. These

compliance times are measured from a date one year after the effective

date of the final rule. (The proposed compliance times are consistent

with those of other similar AD's that the FAA has issued on this

subject.) Generally, operators would be required to complete the

initial basic task before reaching the ``Initial Inspection Time'' plus

one ``Repeat Inspection Time'' interval for the aircraft zone, as

detailed in the Document. The basic task would be required to be

repeated at a time interval not to exceed the ``Repeat Inspection

Time'' interval for that area, as detailed in the Document.

Paragraph (a) includes paragraph (a)(1)(iii), which states that,

for each area that exceeds the initial inspection time for that area,

operators must accomplish the initial basic task at a minimum rate of

one such area every two years, beginning one year after the effective

date of the final rule. The FAA recognizes that this may cause a

hardship on some small operators; in those circumstances, the FAA

anticipates evaluating requests for adjustment to the implementation

rate on a case-by-case basis under the provisions of paragraph (h) of

the proposed rule. (A note to this effect is included in the proposal.)

Operators should note that the proposal does not contain a

paragraph specifically to address repair actions. The FAA considers

that any repairs would be carried out necessarily as a part of each

basic task, as it is defined in the Document. As discussed previously,

a ``basic task'' is defined in the Document as including not only the

pertinent inspection, but any necessary repairs, application of

corrosion inhibitors, and other follow- on procedures, as well.

Paragraph (a) contains a note to reference the portion of the Document

that defines a basic task, and to emphasize the importance of these

corrective actions.

Paragraph (b) of the proposal provides for an optional method of

complying with the rule. In lieu of performing the task-by-task

requirements proposed in paragraph (a), operators may revise their FAA-

approved maintenance/inspection programs to include the corrosion

prevention and control program defined in the Document or an equivalent

program approved by the FAA.

Paragraph (b) also would require that, subsequent to the

accomplishment of the initial basic task, any extensions of Repeat

Inspection Time intervals specified in the Document must be approved by

the FAA.

Any operator electing to comply with proposed paragraph (b) would

be permitted to use an alternative recordkeeping method to that

otherwise required by Federal Aviation Regulations (FAR) section 91.417

or section 121.380, provided it is approved by the FAA and is included

in a revision to the FAA-approved maintenance/inspection program. In

response to questions raised previously concerning recordkeeping and

record retention requirements as they relate to the programmatic

approach proposed in this AD action and other similar proposals that

have been issued applicable to other airplane models, the FAA offers

the following:

Sections 91.417(a)(2)(v) and 121.380(a)(2)(v) of the FAR require

that a record be made of the current status of applicable AD's. With

regard to proposed paragraph (b), such a record would be required to be

made when the maintenance/inspection program is revised to incorporate

the program specified in the Document; at that time, paragraph (b) of

the AD would be fully complied with. Regarding paragraphs (d) through

(g) of this proposal, those paragraphs would impose separate

requirements; therefore, except as discussed below, separate entries

would have to be made to reflect compliance with each of those

paragraphs.

Section 121.380(a)(2)(iv) of the FAR concerns recording ``the

identification of the current inspection status of the aircraft.''

Section 91.417(a)(2)(iv) contains a similar requirement. Because

proposed paragraph (b) would require operators to revise their

maintenance/inspection program to include the program specified in the

Document, each operator's program would be required to identify each

inspection (e.g., ``C'' check) at which each basic task specified in

the Document will be performed on each airplane. By recording the

current inspection status of each airplane, and by maintaining a cross-

reference system between these records and the maintenance/inspection

program revision, it will be possible to determine the current status

of each basic task on each airplane. Once this cross-reference system

has been established, this recording provision of Sections 91 and 121

requires no additional recording beyond what would otherwise be

required normally.

Section 121.380(a)(1) concerns ``records necessary to show that all

requirements for the issuance of an airworthiness release under section

121.709 have been met.'' Section 91.417(a)(1) contains a similar

requirement. These are also referred to as ``dirty fingerprint

records.'' This provision of sections 91 and 121 requires most of the

recording that would result from this proposed AD. Each time a basic

task is performed, the operator would be required to make a ``dirty

fingerprint'' record of the task, identifying what actions were

accomplished. It should be noted, however, that these records are not

different from the records made for any other actions taken under the

operator's maintenance/inspection program.

In addition to the record making requirements, discussed above,

sections 91 and 121 of the FAR impose requirements for record

retention:

Section 121.380(b)(1) and Section 91.417(b)(1) require that the

``dirty fingerprint'' records be retained until the work is repeated or

superseded by other work, or for one year after the work is performed.

Therefore, most of the records resulting from this proposed AD would

not have to be retained indefinitely. However, such retention might

facilitate subsequent transfers, or substantiate requests for

repetitive interval escalations, and therefore, may be in the

operator's interest.

Section 121.380(b)(2) requires that the records specified in

paragraph 121.380(a)(2) [current status of AD's and current inspection

status] be retained and transferred with the airplane at the time it is

sold. Section 91.417(b)(2) contains a similar requirement.

These recording requirements are not considered to be unduly

burdensome and are considered the minimum necessary to enable the

cognizant FAA Maintenance Inspector to perform proper surveillance and

to ensure that the objectives of the proposed rule are being fulfilled.

However, because of the numerous concerns expressed previously by

operators regarding the recordkeeping obligations imposed by section

121.380 with regard to similar rulemaking on corrosion prevention and

control programs, the FAA has included in this proposal certain

provisions for alternative recordkeeping methods. Proposed paragraph

(b)(1) would provide for the development and implementation of such

alternative methods, which must be approved by the FAA. For example,

operators may choose to submit proposals to record compliance with

paragraphs (d) through (g) of the AD by a means other than they

normally use to record AD status. (The FAA has developed guidance

material that will contain information to be considered by FAA

Principal Maintenance Inspectors (PMI) when reviewing proposals for

alternative recordkeeping methods.)

Paragraph (c) of the proposal provides for increasing a ``Repeat

Inspection Time'' interval by up to 10% in order to accommodate

unanticipated scheduling requirements. Operators would be required to

inform the FAA within 30 days of such increases.

Paragraph (d)(1) of the proposal sets forth the reporting actions

that are necessary to be accomplished when Level 3 corrosion is

determined to exist. Within 7 days after such a determination is made,

an operator would be required to accomplish one of the following

actions:

1. Submit a report of the determination to the FAA and complete the

basic task in the affected area on the remainder of the Model F-27

series airplanes in the operator's fleet; or

2. Submit a proposed schedule, for approval by the FAA, for

performing the basic tasks in the affected area on the remainder of the

operator's Model F-27 series fleet; or

3. Submit data substantiating that the Level 3 corrosion was an

isolated occurrence.

Once the FAA has received such a report, it may, in conjunction

with normal surveillance activities, request additional information

regarding the results of the basic tasks performed on the remainder of

the operator's Model F-27 series fleet.

Paragraph (d)(2) of the proposal specifies that the FAA may impose

schedules different from what an operator has proposed under paragraph

(d)(1), if it is found that changes are necessary to ensure that any

other Level 3 corrosion in the operator's Model F-27 series fleet

is detected in a timely manner.

Paragraph (d)(3) of the proposal would require that, within the

time schedule approved by the FAA, the operator must accomplish the

basic tasks in the affected areas on the remaining airplanes in its

Model F-27 series fleet to ensure that any other Level 3 corrosion is

detected.

Paragraph (e) would require that, upon finding corrosion exceeding

Level 1 during a repetitive inspection, an operator must adjust its

program to ensure that future corrosion findings are limited to Level 1

or better. Where corrective action is necessary to reduce corrosion to

Level 1 or better, an operator must submit a proposal for a means of

corrective action for the FAA's approval within 60 days after the

determination of corrosion is made. That means, approved by the FAA,

must then be implemented to reduce future findings of corrosion in that

area to Level 1 or better.

With regard to paragraph (e), it should be noted that if corrosion

is found and it is not considered representative of the operator's

fleet, no further corrective action may be necessary, since a means to

reduce any corrosion to Level 1 or better will have already been

implemented in the operator's program in accordance with proposed

paragraph (a) or (b). For example, if a finding of corrosion is

attributable to a particular spill of mercury or other unique event, or

if corrosion is found on an airplane recently acquired from another

operator, the means specified in the existing program may be adequate

for controlling corrosion in the remainder of the operator's fleet.

Similarly, if an operator has already implemented means to reduce

corrosion in an airplane area based on previous findings, no additional

corrective action may be necessary. In reviewing the reports submitted

in accordance with the AD, the FAA will monitor the effectiveness of

the operator's means to reduce corrosion. If the FAA determines that an

operator has failed to implement adequate means to reduce corrosion to

Level 1 or better, appropriate action will be taken to ensure

compliance with this paragraph.

Paragraph (f) of the proposal concerns adding airplanes to an

operator's fleet, and the procedures that must be followed with regard

to corrosion prevention and control. This paragraph differentiates

between procedures applicable to added airplanes that previously were

maintained in accordance with this AD and those that were not so

maintained. For airplanes that previously have been maintained in

accordance with the proposed requirements of this AD action, the first

basic task in each aircraft zone to be performed by the new operator

would be required to be performed in accordance with either the

previous operator's or the new operator's inspection schedule,

whichever would result in the earlier accomplishment date for that

task. For airplanes that have not been maintained in accordance with

the proposed requirements of this AD action, the first basic task in

each aircraft zone to be performed by the new operator would be

required to be performed before the airplane is placed in service, or

in accordance with a schedule approved by the FAA.

With regard to the requirements of paragraph (f), the FAA considers

it essential that operators ensure that transferred airplanes are

inspected in accordance with the baseline corrosion prevention and

control program on the same basis as if there were continuity in

ownership. Scheduling of the inspections for each airplane must not be

delayed or postponed due to a transfer of ownership; in some cases,

such postponement could continue indefinitely if an airplane is

transferred frequently from one owner to another. The proposed rule

would require that the specified procedures be accomplished before any

operator places into service any airplane subject to the requirements

of the proposed AD.

Paragraph (g) of the proposal would require that reports of Level 2

and Level 3 corrosion be submitted to Fokker within certain time

periods after such corrosion is detected. A note has been included in

this paragraph indicating that reporting to the FAA of any Level 2 or

Level 3 corrosion found as a result of any opportunity inspections is

highly desirable. Operators are not relieved, however, from reporting

corrosion findings as required by FAR section 121.703.

The FAA estimates that 55 airplanes of U.S. registry would be

affected by this proposed AD. It would take an average of approximately

7 work hours per basic task to accomplish the 75 basic tasks called out

in the Document; this represents a total average of 525 work hours. The

average labor rate is $55 per work hour. Based on these figures, the

total cost impact of the proposed AD on U.S. operators for the 6-year

average inspection cycle is estimated to be $1,588,125, or $28,875 per

airplane.

The total cost impact figure discussed above is based on

assumptions that no operator has yet accomplished any of the proposed

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted.

The FAA recognizes that the obligation to maintain aircraft in an

airworthy condition is vital, but sometimes expensive. Because AD's

require specific actions to address specific unsafe conditions, they

appear to impose costs that would not otherwise be borne by operators.

However, because of the general obligation of operators to maintain

aircraft in an airworthy condition, this appearance is deceptive.

Attributing those costs solely to the issuance of this AD is

unrealistic because, in the interest of maintaining safe aircraft, most

prudent operators would accomplish the required actions even if they

were not required to do so by the AD.

A full cost-benefit analysis has not been accomplished for this

proposed AD. As a matter of law, in order to be airworthy, an aircraft

must conform to its type design and be in a condition for safe

operation. The type design is approved only after the FAA makes a

determination that it complies with all applicable airworthiness

requirements. In adopting and maintaining those requirements, the FAA

has already made the determination that they establish a level of

safety that is cost-beneficial. When the FAA, as in this proposed AD,

makes a finding of an unsafe condition, this means that this cost-

beneficial level of safety is no longer being achieved and that the

proposed actions are necessary to restore that level of safety. Because

this level of safety has already been determined to be cost-beneficial,

a full cost-benefit analysis for this proposed AD would be redundant

and unnecessary.

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.

For the reasons discussed above, I certify that this proposed

regulation (1) is not a ``significant regulatory action'' under

Executive Order 12866; (2) is not a ``significant rule'' under the DOT

Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);

and (3) if promulgated, 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. A copy of the draft

regulatory evaluation prepared for this action is contained in the

Rules Docket. A copy of it may be obtained by contacting the Rules

Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend 14

CFR part 39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Fokker: Docket 93-NM-76-AD.

Applicability: Model F-27 Mark 100, 200, 300, 400, 500, 600,

700, and 800 series airplanes (does not include Model F-27 MK 050

series airplanes), certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

Note 1: This AD references Fokker Document SE-291, ``F-27

Corrosion Control Program,'' including all revisions through October

1, 1993, (hereafter referred to as ``the Document''), for basic

tasks, definitions of corrosion levels, compliance times, and

reporting requirements. In addition, this AD specifies inspection

and reporting requirements beyond those included in the Document.

Where there are differences between the AD and the Document, the AD

prevails.

Note 2: As used throughout this AD, the term ``the FAA'' is

defined differently for different operators, as follows: For those

operators complying with paragraph (a) of this AD, ``the FAA'' is

defined as ``the Manager of the Standardization Branch, ANM-113,

FAA, Transport Airplane Directorate.'' For those operators operating

under Federal Aviation Regulation (FAR) part 121 or 129, and

complying with paragraph (b) of this AD, ``the FAA'' is defined as

``the cognizant Principal Maintenance Inspector (PMI).'' For those

operators operating under FAR part 91 or 125, and complying with

paragraph (b) of this AD, ``the FAA'' is defined as ``the cognizant

Maintenance Inspector at the appropriate FAA Flight Standards

office.''

Note 3: The FAA recommends that priority for implementing the

corrosion prevention and control program, specified in this AD, be

given to older aircraft and areas requiring a significant upgrade of

previous maintenance procedures to meet the program requirements.

To preclude degradation of the structural capabilities of the

airplane due to the problems associated with corrosion, accomplish

the following:

(a) Except as provided in paragraph (b) of this AD, complete

each of the basic tasks specified in section 2.4 of the Document in

accordance with the procedures of the Document, and the schedule

specified in paragraphs (a)(1) and (a)(2) of this AD.

Note 4: A ``basic task,'' as defined in section 2.4 of the

Document, includes inspections; procedures for a corrective action,

including repairs, under identified circumstances; application of

sealants or corrosion inhibitors; and other follow-on actions.

Note 5: Airplane ``areas'' are those items listed in columnar

form in the ``ACTION'' statement of each task, as listed in the

Document.

Note 6: Basic tasks completed in accordance with the Document

before the effective date of this AD may be credited for compliance

with the initial basic task requirements of paragraph (a)(1) of this

AD.

Note 7: Where non-destructive inspection (NDI) methods are

employed, in accordance with section 2.4 of the Document, the

standards and procedures used must be acceptable to the

Administrator in accordance with FAR section 43.13.

(1) Complete the initial basic task of each aircraft zone

specified in section 2.4 of the Document as follows:

(i) For airplane areas that have not yet exceeded the ``Initial

Inspection Time (IIT)'' for a basic task as of one year after the

effective date of this AD: Initial compliance must occur no later

than the IIT, or no later than one Repeat Inspection Time (RIT)

interval measured from a date one year after the effective date of

this AD, whichever occurs later.

(ii) For airplane areas that have exceeded the IIT for a

particular basic task as of one year after the effective date of

this AD: Initial compliance must occur within one RIT interval for

that task, or within 6 years, measured from a date one year after

the effective date of this AD, whichever occurs first.

(iii) Notwithstanding paragraphs (a)(1)(i) and (a)(1)(ii) of

this AD, accomplish the initial basic task, for each area that

exceeds the IIT for that area, at a minimum rate of one such area

every two years, beginning one year after the effective date of this

AD.

Note 8: This paragraph does not require inspection of any area

that has not exceeded the IIT for that area.

Note 9: This minimum rate requirement may cause an undue

hardship on some small operators. In those circumstances, requests

for adjustments to the implementation rate will be evaluated on a

case-by-case basis under the provisions of paragraph (h) of this AD.

(2) Repeat each basic task at a time interval not to exceed the

RIT interval specified in the Document for that task.

(b) As an alternative to the requirements of paragraph (a) of

this AD: Prior to one year after the effective date of this AD,

revise the FAA-approved maintenance/inspection program to include

the corrosion control program specified in the Document; or to

include an equivalent program that is approved by the FAA. In all

cases, the initial basic task for each airplane area must be

completed in accordance with the compliance schedule specified in

paragraph (a)(1) of this AD.

(1) Any operator complying with paragraph (b) of this AD may use

an alternative recordkeeping method to that otherwise required by

FAR section 91.417 or section 121.380 for the actions required by

this AD, provided it is approved by the FAA and is included in a

revision to the FAA-approved maintenance/inspection program.

(2) Subsequent to the accomplishment of the initial basic task,

extensions of RIT intervals specified in the Document must be

approved by the FAA.

(c) To accommodate unanticipated scheduling requirements, it is

acceptable for an RIT interval to be increased by up to 10%, but not

to exceed 6 months. The FAA must be informed, in writing, of any

such extension within 30 days after such adjustment of the schedule.

(d)(1) If, as a result of any inspection conducted in accordance

with paragraphs (a) or (b) of this AD, Level 3 corrosion is

determined to exist in any airplane area, accomplish either

paragraph (d)(1)(i) or (d)(1)(ii) within 7 days after such

determination:

(i) Submit a report of that determination to the FAA and

complete the basic task in the affected aircraft zones on all Model

F-27 series airplanes in the operator's fleet; or

(ii) Submit to the FAA for approval one of the following:

(A) A proposed schedule for performing the basic tasks in the

affected aircraft zones on the remaining Model F-27 series airplanes

in the operator's fleet, which is adequate to ensure that any other

Level 3 corrosion is detected in a timely manner, along with

substantiating data for that schedule; or

(B) Data substantiating that the Level 3 corrosion found is an

isolated occurrence.

Note: 10: Notwithstanding the provisions of section 2.1 of the

Document, which would permit corrosion that otherwise meets the

definition of Level 3 corrosion (i.e., which is determined to be a

potentially urgent airworthiness concern requiring expeditious

action) to be treated as Level 1 if the operator finds that it ``can

be attributed to an event not typical of the operator's usage of

other airplanes in the same fleet,'' this paragraph requires that

data substantiating any such finding be submitted to the FAA (ref.

Note 2 of this AD) for approval.

(2) The FAA may impose schedules other than those proposed, upon

finding that such changes are necessary to ensure that any other

Level 3 corrosion is detected in a timely manner.

(3) Within the time schedule approved under paragraph (d)(1) or

(d)(2) of this AD, accomplish the basic tasks in the affected

aircraft zones of the remaining Model F-27 series airplanes in the

operator's fleet.

(e) If, as a result of any inspection after the initial

inspection conducted in accordance with paragraph (a) or (b) of this

AD, it is determined that corrosion findings exceed Level 1 in any

area, within 60 days after such determination, implement a means,

approved by the FAA, to reduce future findings of corrosion in that

area to Level 1 or better.

(f) Before any operator places into service any airplane subject

to the requirements of this AD, a schedule for the accomplishment of

basic tasks required by this AD must be established in accordance

with paragraph (f)(1) or (f)(2) of this AD, as applicable:

(1) For airplanes previously maintained in accordance with this

AD, the first basic task in each aircraft zone to be performed by

the new operator must be accomplished in accordance with the

previous operator's schedule or with the new operator's schedule,

whichever would result in the earlier accomplishment date for that

task. After each basic task has been performed once, each subsequent

task must be performed in accordance with the new operator's

schedule.

(2) For airplanes that have not been previously maintained in

accordance with this AD, the first basic task for each aircraft zone

to be performed by the new operator must be accomplished prior to

further flight or in accordance with a schedule approved by the FAA.

(g) Within 7 days after the date of detection of any Level 3

corrosion, and within 3 months after the date of detection of any

Level 2 corrosion, submit a report to Fokker of such findings, in

accordance with section 2.5 of the Document.

Note 11: Reporting to the FAA of Level 2 and Level 3 corrosion

found as a result of any opportunity inspections is highly

desirable.

(h) An alternative method of compliance or adjustment of the

compliance time, which provides an acceptable level of safety, may

be used when approved by the Manager, Standardization Branch, ANM-

113, FAA, Transport Airplane Directorate. Operators shall submit

their requests through the cognizant Maintenance Inspector at the

appropriate FAA Flight Standards office, who may concur or comment

and then send it to the Manager, Standardization Branch, ANM-113.

Note 12: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Standardization Branch, ANM-113.

(i) Special flight permits may be issued in accordance with FAR

21.197 and 21.199 to operate the airplane to a location where the

requirements of this AD can be accomplished.

(j) Reports of inspection results required by this AD have been

approved by the Office of Management and Budget (OMB) under the

provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et

seq.) and have been assigned OMB Control Number 2120-0056.

Issued in Renton, Washington, on March 8, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-5850 Filed 3-11-94; 8:45 am]

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