AD 98-20-03

This amendment adopts a new airworthiness directive (AD), applicable to all Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes, that requires repetitive inspections of the center joint of the main landing gear (MLG) torque link and the MLG assembly for excessive free-play; and correction, if necessary. This AD also requires installation of new MLG torque link dampers, which constitutes terminating action for the repetitive inspections; and revision of the FAA-approved maintenance program to incorporate inspections and overhaul of the new torque link dampers. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent the failure of MLG torque links, which could result in reduced controllability of the airplane on the ground during takeoff or landing.

Final rule

98-20-03 FOKKER SERVICES B.V.: Amendment 39-10769. Docket 98-NM-28-AD.

Applicability: All Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent the failure of main landing gear (MLG) torque links, which could result in reduced controllability of the airplane on the ground during takeoff or landing, accomplish the following:

(a) Within 1,000 flight cycles after the effective date of this AD, perform a visual inspection of the center joint of the MLG torque link for excessive free play, in accordance with Part 1.D. of the Accomplishment Instructions of Fokker Service Bulletin F28/32-151, Revision 1, dated March 12, 1997.

(1) If no discrepancy is detected, repeat the visual inspection thereafter at intervals not to exceed 1,000 flight cycles.

(2) If any discrepancy is detected, prior to further flight, correct the discrepant condition in accordance with Part 1.D. of the Accomplishment Instructions of the service bulletin. Repeat the visual inspection thereafter at intervals not to exceed 1,000 flight cycles.

NOTE 2: Part 1.D. of the Accomplishment Instructions of Fokker Service BulletinF28/32-151, Revision 1, dated March 12, 1997, references Fokker F.28 Airplane Maintenance Manual (AMM), Chapter 32-10-04, as an additional source of service information to accomplish the actions required by this AD.

(b) Within 3,000 flight cycles after the effective date of this AD, perform a visual inspection of the MLG assembly for excessive free play, in accordance with Parts 1.A., 1.B., and 1.C. of the Accomplishment Instructions of Fokker Service Bulletin F28/32-151, Revision 1, dated March 12, 1997.

(1) If no discrepancy is detected, repeat the visual inspection thereafter at intervals not to exceed 3,000 flight cycles.

(2) If any discrepancy is detected, prior to further flight, correct the discrepant condition in accordance with Parts 1.A., 1.B., and/or 1.C. of the Accomplishment Instructions of the service bulletin, as applicable. Repeat the visual inspection thereafter at intervals not to exceed 3,000 flight cycles.

NOTE 3: Parts 1.A., 1.B., and 1.C. of the Accomplishment Instructions of Fokker Service Bulletin F28/32-151, Revision 1, dated March 12, 1997, reference Fokker F.28 AMM, Chapters 32-10-01, 32-10-00, and 32-10-04, as additional sources of service information to accomplish the actions required by this AD.

(c) Within 30 months after the effective date of this AD, accomplish paragraphs (c)(1) and (c)(2) of this AD.

(1) Install torque link dampers and associated sub-assemblies in accordance with Part 2 of the Accomplishment Instructions of Fokker Service Bulletin F28/32-151, Revision 1, dated March 12, 1997. Accomplishment of the installation constitutes terminating action for the repetitive inspection requirements of this AD.

(2) Revise the FAA-approved maintenance program to incorporate a visual inspection of the oil level of the torque-link dampers thereafter at intervals not to exceed 250 flight hours, and incorporate a scheduled overhaul of each damper concurrent with the overhaul of the MLG on which itis installed, in accordance with Part 2 of the Accomplishment Instructions of Fokker Service Bulletin F28/32-151, Revision 1, dated March 12, 1997.

NOTE 4: After the maintenance program is revised to include the required inspection and overhaul actions in accordance with paragraph (c)(2) of this AD, operators do not need to make a maintenance log entry to show compliance with this AD each time those actions are accomplished thereafter.

(d) 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, International Branch, ANM-116, 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, International Branch, ANM-116.

NOTE 5: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

(e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(f) The actions shall be done in accordance with Fokker Service Bulletin F28/32-151, Revision 1, dated March 12, 1997, which includes the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page
1-6, 10
1
March 12, 1997
7-9, 11-13
Original
August 9, 1996

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Fokker Services B.V., Technical Support Department, P.O. Box 75047, 1117 ZN Schiphol Airport, the Netherlands. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 6: The subject of this AD is addressed in Dutch airworthiness directive BLA 1996-103(A), dated August 30, 1996.

(g) This amendment becomes effective on October 26, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to all Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes was published in the Federal Register on April 2, 1998 (63 FR 16177). That action proposed to require repetitive inspections of the center joint of the main landing gear (MLG) torque link and the MLG assembly for excessive free-play; and correction, if necessary. That action also proposed to require installation of new MLG torque link dampers, which would constitute terminating action for the repetitive inspections; and revision of the FAA- approved maintenance program to incorporate inspections and overhaul of the new torque link dampers.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Request that Final Rule Not Be Issued
The single commenter, an operator, states that the requirements of the proposed rule are unnecessary. The commenter states that the incident that initiated the Dutch airworthiness directive was caused by certain operators' failure to adequately maintain their landing gear, wheels, brakes, and tires. The commenter further notes that accomplishment of the proposed installation of a shimmy damper could allow airlines to lengthen the time between replacement and repair of those worn parts, which would exacerbate the condition. The commenter concludes that the requirements of the proposed rule would unfairly penalize operators who have adequately maintained their airplanes and have no problems with vibration.

The FAA does not concur that the requirements of this AD are unnecessary. As explained in the preamble of the proposed rule, the Dutch airworthiness authority [Rijksluchtvaartdienst (RLD)] advised the FAA that it received numerous reports of MLG torque link failure on in-service airplanes. The cause of these failures has been attributed to one or more deficiencies, such as excessive play in hinges and bearings, worn or non-approved tires, or nitrogen or tire pressure that is too high. Such deficiencies caused reduced natural stability of the MLG in a lateral and torsional mode during landing, resulting in vibration and consequent failure of the MLG torque links.

Although the deficiencies are maintenance-related, the FAA considers that the large number of deficiencies reported is sufficient evidence that an unsafe condition exists. Therefore, this AD action addresses certain identified deficiencies that may result in an unsafe condition (reduced controllability of the airplane on the ground during takeoff or landing), and requires corrective action, if necessary.

Request for Approval of Alternative Method of Compliance
The commenter also requests approval of an alternative method of compliance that consists of an enhanced maintenance program for landing gear components. The commenter provided correspondence indicating that Transport Canada Aviation (the airworthiness authority for Canada) has approved the commenter's request for an alternative method of compliance based on the enhanced maintenance program.

The FAA does not concur that this final rule should be revised to reflect approval of an alternative method of compliance. The information submitted by the commenter is insufficient for the FAA to evaluate the commenter's suggestion. However, under the provisions of paragraph (d) of this final rule, the FAA may consider requests for approval of an alternative method of compliance if sufficient data are submitted to substantiate that such a design change would provide an acceptable level of safety.

Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact
The FAA estimates that 27 airplanes of U.S. registry will be affected by this AD. It will take approximately 3 work hours per airplane to accomplish the required inspections, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspections required by this AD on U.S. operators is estimated to be $4,860, or $180 per airplane, per inspection cycle.

It will take approximately 18 work hours per airplane to accomplish the required installation/modification, at an average labor rate of $60 per work hour. Required parts will cost approximately $90,000 per airplane. Based on these figures, the cost impact of the installation/modification required by this AD on U.S. operators is estimated to be $2,459,160, or $91,080 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions inthe future if this AD were not adopted.

Regulatory Impact
The regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: