Airworthiness Directives; Fokker Model F27 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-201-AD]

Airworthiness Directives; Fokker Model F27 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 F27 series

airplanes. This proposal would require replacement of certain bolts

that are currently installed in various flight critical components of

the airplane. 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 reduced structural integrity of various flight

critical components of the airplane.

DATES: Comments must be received by April 5, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 93-NM-201-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-201-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-201-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. 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 needs to be

focused on the aging airplane fleet to maintain 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 Program (SIP); and

5. Assess repair quality.

The Working Group assigned to review the Fokker Model F27 series

airplanes has completed its work on Item (1), above. The Working Group

has identified certain service difficulties that warrant mandatory

modification of these airplanes. The Working Group considers that these

service difficulties warrant mandatory modification of the airplane to

assure continued operational safety of Model F27 airplanes that have

exceeded their economic design goal.

The ``economic design goal'' of an airplane is typically considered

to be the period of service after which a substantial increase in the

maintenance costs is expected to take place in order to assure

continued operational safety. The economic design goal for Fokker Model

F27 series airplanes is 20 years for structural problems associated

with environmental deterioration, and 60,000 flight cycles for

structural problems associated with fatigue damage.

The Working Group has recommended Fokker Service Bulletin F27/51-

10, Revision 2, dated June 12, 1993, for mandatory modification. This

service bulletin describes procedures for replacement of AN bolts that

are currently installed in the following flight critical components of

the airplane with NAS bolts. The manufacturing process used to produce

NAS bolts yields superior quality bolts that are anticipated to

preclude cracking in these areas:

1. Flight controls (including the push-pull rods of the trim drive

mechanism; aileron, rudder, elevator, and elevator trim tab controls;

and elevator hinge support assemblies).

2. Control surfaces (including elevator, rudder, aileron, and tab

hinge bolts).

3. Fuel control installations.

4. Engine mount and nacelle brace installations.

5. Engine control installations.

This service bulletin has been amended by Service Bulletin Change

Notification F27/51 - 10REV2/01, dated October 1, 1993, to correct an

error in a part number referenced in the service bulletin.

The Rijksluchtvaartdienst (RLD), which is the airworthiness

authority for the Netherlands, classified the original release of the

service bulletin as mandatory and issued Netherlands Airworthiness

Directive (BLA) 91-111, dated September 13, 1991, in order to assure

the continued airworthiness of these airplanes in the Netherlands.

This airplane model is manufactured in the Netherlands and is type

certificated for operation in the United States under the provisions of

Sec. 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 an unsafe condition has been identified that is likely to

exist or develop on other airplanes of the same type design registered

in the United States, the proposed AD would require replacement of AN

bolts that are currently installed in various flight critical

components of the airplane with NAS bolts. The actions would be

required to be accomplished in accordance with the service bulletin

described previously.

The proposed compliance time for implementation of this

modification program is within 3 years after the effective date of the

AD. This time interval was based upon the ability of the manufacturer

to provide the parts necessary for the modification, and the time

necessary to incorporate the modification.

In the interim, safety will be provided by various means currently

in place that are considered satisfactory to detect damage prior to the

occurrence of an unsafe condition. These include operators' ongoing

basic maintenance programs; continuing inspections required by numerous

AD's issued previously; the SIP mandated by AD 92-19-07, Amendment 39-

8365 (57 FR 42693, September 16, 1992); the FAA's increased emphasis on

surveillance of operators' maintenance programs and procedures; and the

FAA's participation in programs to physically inspect high-time

airplanes during scheduled heavy maintenance.

The FAA estimates that 39 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 250 work

hours per airplane to accomplish the proposed actions, and that the

average labor rate is $55 per work hour. Required parts would cost

approximately $690 per airplane. Based on these figures, the total cost

impact of the proposed AD on U.S. operators is estimated to be

$563,160, or $14,440 per airplane. This total cost figure assumes that

no operator has yet accomplished the proposed requirements of this AD

action.

The FAA recognizes that the proposed modification would require a

large number of work hours to accomplish. However, the 3-year

compliance time specified in paragraph (a) of this proposed AD should

allow ample time for the replacement of AN bolts to be accomplished

coincidentally with scheduled major airplane inspection and maintenance

activities, thereby minimizing the costs associated with special

airplane scheduling.

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 14a CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Fokker: Docket 93-NM-201-AD.

Applicability: Model F27 series airplanes, having serial numbers

10102 through 10612 inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent reduced structural integrity of various flight

critical components of the airplane, accomplish the following:

(a) Within 3 years after the effective date of this AD, remove

AN bolts that are currently installed in the flight controls,

control surfaces, fuel control installations, engine mount and

nacelle brace installations, and engine control installations, and

replace them with NAS 1303/1320 bolts, in accordance with Fokker

Service Bulletin F27/51-10, Revision 2, dated June 12, 1993, as

amended by Service Bulletin Change Notification F27/51 - 10REV2/01,

dated October 1, 1993.

(b) As of the effective date of this AD, no person shall install

on any airplane any AN bolt having a part number that is listed in

Fokker Service Bulletin F27/51-10, Revision 2, dated June 12, 1993,

as amended by Service Bulletin Change Notification F27/51 - 10REV2/

01, dated October 1, 1993, in any of the flight critical components

identified in the service bulletin.

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

compliance time that provides an acceptable level of safety may be

used if approved by the Manager, Standardization Branch, ANM-113,

FAA, Transport Airplane Directorate. Operators shall submit their

requests through an appropriate FAA Principal Maintenance Inspector,

who may add comments and then send it to the Manager,

Standardization Branch, ANM-113.

Note: Information concerning the existence of approved

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

obtained from the Standardization Branch, ANM-113.

(d) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the

airplane to a location where the requirements of this AD can be

accomplished.

Issued in Renton, Washington, on February 3, 1994.

N. B. Martenson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-2917 Filed 2-8-94; 8:45 am]

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