01-25182. Airworthiness Directives; Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes, that requires repetitive eddy current inspections to detect cracks in the upper girder of the two main landing gear (MLG) brackets; and repair of a cracked bracket followed by repetitive inspections, or replacement of a cracked MLG bracket with an improved bracket, as applicable. This AD also provides for an optional terminating action for certain requirements of this AD. The actions specified by this AD are intended to detect and correct cracks in the upper girder of the MLG bracket, which could progress into the vertical stiffeners of the MLG bracket and result in reduced structural integrity of the landing gear. This action is intended to address the identified unsafe condition.

DATES:

Effective November 15, 2001.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of November 15, 2001.

ADDRESSES:

The service information referenced in this AD may be obtained from Fokker Services B.V., P.O. Box 231, 2150 AE Nieuw-Vennep, the Netherlands. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Dan Rodina, Aerospace Engineer, International Branch, ANM-116, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

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 certain Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on May 4, 2001 (66 FR 22479). That action proposed to require repetitive eddy current inspections to detect cracks in the upper girder of the two main landing gear (MLG) brackets; and repair of a cracked bracket followed by repetitive inspections, or replacement of a cracked MLG bracket with an improved bracket, as applicable. That action also proposed to provide for optional terminating action for certain requirements of this AD.

Comments

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

Requests To Allow Flight with Cracks

One commenter requests that airplanes be allowed to fly with cracks within the range of 16 millimeters (mm) (0.630 inches) to 40 mm (1.575 inches) on the MLG bracket, with repetitive inspections, for a period of six months or until the next heavy maintenance check, whichever occurs first. A second commenter requests that the replacement of the MLG bracket required by paragraph (b) of the proposed AD be required only when cracks exceed 40 mm (1.575 inches), as indicated in Dutch airworthiness directive 1999-045/2 dated October 31, 2000, and Fokker Service Bulletin F28/59-90, Revision 1, dated August 28, 2000. Both commenters point out that the proposed replacement of the MLG bracket would require extended downtime and would be a disruption to the operator's operating schedule if the repair cannot be accomplished in conjunction with a heavy maintenance check. The commenters state that requiring replacement of the MLG bracket with cracks between 15 mm (0.591 inches) and 40 mm (1.575 inches) could create severe logistical disturbances and a significant cost impact for the operators, with no added safety benefit.

The FAA partially agrees with these commenters. The FAA acknowledges that if any crack is found, no matter what its length, the repair or replacement required by paragraph (a) or (c) of the AD requires a considerable number of work hours. We also acknowledge that unless the repetitive inspections required by paragraph (a) of this AD are scheduled during a heavy maintenance check, any crack finding could potentially remove the airplane from service and possibly result in a disruption to operating schedules.

To address this issue, the Rijksluchtvaartdienst (RLD), the airworthiness authority for the Netherlands, has allowed a repeat inspection at intervals of 250 flight cycles, or one month, as an alternate to replacement. Neither Dutch airworthiness directive 1999-045/2, dated October 31, 2000, nor Fokker Service Bulletin F28/59-90, Revision 1, dated August 28, 2000, puts a time limit on this replacement deferral. If the FAA were to allow for this reduced inspection cycle in lieu of repair, we would require a time limit.

While recognizing that repair deferrals may be necessary at times, FAA policy is intended to minimize adverse human factors relating to the lack of reliability of long-term repetitive inspections, which may reduce the safety of the type certificated design if such repair deferrals are practiced routinely. Based upon correspondence with the manufacturer, the FAA has determined that no structural detrimental permanent deformation will occur in the MLG and surrounding structure under the full limit load when a stress corrosion crack with a length of 40 mm or less is present at the indicated location. In addition, no failure will occur in the MLG bracket or surrounding structure under the ultimate load. If the crack does not exceed 40 mm in length it will not cause loss of function or interfere with other necessary parts of the design. Experience supports the results of the theoretical analysis and the FAA has a high degree of confidence that operation with a known crack is safe as long as it is closely monitored.

Consequently, paragraph (a) of the final rule has been revised to allow for a repair deferral period of not more than 18 months if a crack of 40 mm or less is detected, provided the crack is monitored at the reduced inspection interval specified in the service bulletin. In addition, paragraph (a) has been revised and reformatted to clarify that terminating action is not necessary; paragraph (c) has been removed; and subsequent paragraphs have been renumbered accordingly.

Under the provisions of paragraph (e) of the final rule, the FAA may approve requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety.

Clarification of Service Bulletin Reference

The FAA's intent in this rule was to require that repairs specified in paragraph (a) be performed in accordance with Part 3 (“The Repairs and the Repetitive Inspections”) of the Accomplishment Instructions of Fokker Service Bulletin F28/57-90, Revision 1, dated August 28, 2000. As issued, the supplemental notice of proposed rulemaking contained an incorrect reference to a service bulletin paragraph. The final rule has been revised to correct this error and to clarify the appropriate requirements.

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 with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact

The FAA estimates that 8 Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $960, or $120 per airplane.

The cost impact figure discussed above is 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 in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.

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:

2001-20-08 Fokker Services B.V.: Amendment 39-12456. Docket 99-NM-220-AD.

Applicability: Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes; serial numbers 11003 through 11091 inclusive, 11094 through 11171 inclusive, 11991, and 11992; 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 (e) 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 detect and correct cracks in the upper girder of the main landing gear (MLG) bracket, which could progress into the vertical stiffeners of the MLG bracket and result in reduced structural integrity of the landing gear, accomplish the following:

Repetitive Inspections and Corrective Actions

(a) Within 12 months after the effective date of this AD, perform an eddy current inspection of the upper girder of the MLG brackets on the left and right sides of the airplane for cracks, in accordance with the Accomplishment Instructions of Fokker Service Bulletin F28/57-90, Revision 1, dated August 28, 2000.

(1) If no cracks are found, repeat the inspection at least every 18 months unless the terminating action in paragraph (c) of this AD has been accomplished.

(2) Except as provided by paragraph (d) of this AD, if any crack is found, accomplish a repair as specified in Part 3, “The Repairs and the Repetitive Inspections”, of the Accomplishment Instructions of the service bulletin, or accomplish the specified action at the time shown in paragraph (a)(2)(i), (a)(2)(ii), (a)(2)(iii), or (a)(2)(iv) of this AD, as applicable.

(i) For airplanes on which a crack 15 millimeters (mm) in length or less is found: repair as specified in paragraph (a)(2) or, for a period of time not to exceed 18 months until accomplishment of a repair, repeat the inspection every 250 flight cycles or 1 month, whichever occurs first, in accordance with the service bulletin. After the repair has been accomplished, repeat the inspection required in paragraph (a) of this AD at least every 18 months unless the terminating action in paragraph (c) of this AD has been accomplished.

(ii) For airplanes on which a crack greater than 15 mm but less than or equal to 25 mm in length is found: Within 18 months from the date of the in­spection, accomplish the terminating action in paragraph (c) of this AD. From the date of the inspection until the accomplishment of the terminating action, repeat the inspection every 250 flight cycles or 1 month, whichever occurs first .

(iii) For airplanes on which a crack greater than 25 mm but less than or equal to 40 mm in length is found: Within 18 months from the date of the inspection, accomplish the terminating action in paragraph (c) of this AD. From the date of the inspection until the accomplishment of the terminating action, repeat the inspection every 50 flight cycles or 1 week, whichever occurs first.

(iv) For airplanes on which a crack greater than 40 mm in length is found: Prior to further flight, except as provided by paragraph (d) of this AD, accomplish the terminating action in paragraph (c) of this AD.

Note 2:

Inspections accomplished before the effective date of this AD in accordance with Fokker Service Bulletin F28/57-90, dated March 1, 1999, are considered acceptable for compliance with paragraph (a) of this AD.

Reporting Requirement

(b) Within 10 days after accomplishing each inspection required by paragraph (a) of this AD, submit a report of the inspection results to: Fokker Services B.V., Technical Services, Attn: Manager Airline Support, P.O. Box 231, 2150 AE Nieuw-Vennep, the Netherlands. Information collection requirements contained in this regulation 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.

Terminating Action

(c) If required by paragraph (a) of this AD, except as provided by paragraph (d) of this AD, replacement of the MLG bracket with a new, improved bracket (including measuring the position of the existing MLG bracket, removing the existing bracket and attachment fittings, checking alignment of the fastener holes, measuring gaps, installing a shim, and aligning the new bracket), in accordance with Fokker Proforma Service Bulletin F28/57-92, dated July 1, 1999, constitutes terminating action for the repetitive inspections specified in paragraph (a) of this AD for the replaced bracket.

(d) If any discrepancy is detected during accomplishment of the replacement procedures, and the service bulletin or any appendix to the service bulletin specifies to contact Fokker for appropriate action: Prior to further flight, repair in accordance with a method approved by either the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate; or the Rijksluchtvaartdienst (or it delegated agent).

Alternative Methods of Compliance

(e) 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. 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 3:

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

Special Flight Permits

(f) 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.

Incorporation by Reference

(g) Except as provided by paragraph (d) of this AD, the actions shall be performed in accordance with Fokker Service Bulletin F28/57-90, Revision 1, dated August 28, 2000; and Fokker Proforma Service Bulletin F28/57-92, dated July 1, 1999; as applicable. 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., P.O. Box 231, 2150 AE Nieuw-Vennep, 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 4:

The subject of this AD is addressed in Dutch airworthiness directive 1999-045/2, dated October 31, 2000.

Effective Date

(h) This amendment becomes effective on November 15, 2001.

Issued in Renton, Washington, on October 2, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.