AD 94-22-05

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires inspections to detect cracks of certain demountable flange (inboard) wheel subassemblies and of the bolt bosses on certain demountable flange (outboard) wheel subassemblies, and modification or replacement of the wheel subassemblies. This amendment is prompted by reports of cracks and broken spokes found on certain main wheel assemblies of these airplanes. The actions specified by this AD are intended to prevent loss of a main wheel assembly during takeoff or landing.

Final rule

94-22-05 FOKKER: Amendment 39-9054. Docket 93-NM-197-AD.
Applicability: Model F28 Mark 0100 series airplanes equipped with Aircraft Braking Systems Corporation (ABSC) main wheel assembly, part number 5008131-4, serial numbers APR91-0570 through FEB93-0965 inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent loss of a main wheel assembly during takeoff or landing, accomplish the following:

(a) For airplanes equipped with a demountable flange (inboard) wheel subassembly, part number 5008142-4, serial numbers APR91-0570 through OCT92-0858 inclusive, or S-APR91-0097 through S-MAY92-0126 inclusive: Within 100 landings after the effective date of this AD, or at the next tire change, whichever occurs first, perform an eddy current inspection to detect cracks of the wheel subassembly, in accordance with paragraph C. of SECTION II - ACCOMPLISHMENT INSTRUCTIONS of ABSC Service Bulletin Fo100-32-46, datedDecember 24, 1992. Repeat this inspection thereafter at intervals not to exceed 500 landings or at each tire change, whichever occurs first.

(1) If no crack is found during any inspection required by paragraph (a) of this AD: Prior to further flight following the third inspection accomplished after the effective date of this AD, modify the wheel subassembly in accordance with paragraph D. of SECTION II - ACCOMPLISHMENT INSTRUCTIONS of the service bulletin. After modification, continue to inspect in accordance with paragraph (a) of this AD. If no crack is found during the first two inspections conducted after modification, no further action is required by this paragraph.

(2) If any crack is found during any inspection required by paragraph (a) of this AD, prior to further flight, replace the wheel subassembly, part number 5008142-4, with a serviceable part in accordance with the Airplane Maintenance Manual. Such replacement constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD.

(b) For airplanes equipped with a demountable flange (outboard) wheel subassembly, part number 5008140-1, serial numbers APR91-0570 through FEB93-0965 inclusive, or S-MAR91-0002 through S-FEB93-0010 inclusive: Within 100 landings after the effective date of this AD, or at the next tire change, whichever occurs first, perform an eddy current inspection to detect cracks of the bolt bosses of the wheel subassembly, in accordance with paragraph B. of SECTION II - ACCOMPLISHMENT INSTRUCTIONS of ABSC Service Bulletin Fo100-32-48, dated March 10, 1993. Repeat this inspection thereafter at intervals not to exceed 500 landings or at each tire change, whichever occurs first.

(1) If no crack is found during any inspection required by paragraph (b) of this AD: Prior to further flight following the third inspection accomplished after the effective date of this AD, modify the wheel subassembly in accordance with paragraph C. of SECTION II - ACCOMPLISHMENT INSTRUCTIONS of the service bulletin. Such modification constitutes terminating action for the repetitive inspections required by paragraph (b) of this AD.

(2) If any crack is found during any inspection required by paragraph (b) of this AD, prior to further flight, replace the wheel subassembly, part number 5008140-1, with a serviceable part in accordance with the Airplane Maintenance Manual. Such replacement constitutes terminating action for the repetitive inspections required by paragraph (b) of this AD.

(c) After the effective date of this AD, no person shall install any of the following parts on any airplane unless that part has been inspected in accordance with paragraph (a) or (b) of this AD, as applicable. Following installation of any such part, the part must be repetitively inspected and modified in accordance with paragraphs (a) or (b) of this AD, as applicable.

(1) ABSC demountable flange (inboard) wheel subassembly, part number5008142-4, having serial numbers APR91-0570 through OCT92-0858 inclusive, or S-APR91- 0097 through S-MAY92-0126 inclusive;

(2) ABSC demountable flange (outboard) wheel subassembly, part number 5008140-1, having serial numbers APR91-0570 through FEB93-0965 inclusive, or S-MAR91- 0002 through S-FEB93-0010 inclusive;

(3) Main wheel assembly, part number 5008131-4, having serial numbers APR91-0570 through FEB 93-0965 inclusive.

(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, 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 fromthe Standardization Branch, ANM-113.

(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 inspections and modifications shall be done in accordance with ABSC Service Bulletin Fo100-32-46, dated December 24, 1992; or ABSC Service Bulletin Fo100-32-48, dated March 10, 1993. 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 Aircraft USA, Inc., 1199 North Fairfax Street, Alexandria, Virginia 22314. 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.

(g) This amendment becomes effective on December 12, 1994.

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 F28 Mark 0100 series airplanes was published in the Federal Register on February 28, 1994 (59 FR 9450). That action proposed to require inspections to detect cracks of certain demountable flange (inboard) wheel subassemblies and of the bolt bosses on certain demountable flange (outboard) wheel subassemblies, and modification or replacement of the wheel subassemblies.

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

One commenter supports the proposed rule.

One commenter requests that proposed paragraphs (a) and (b) be revised to provide credit for inspections accomplished within the last 500 landings before the final rule becomes effective. This commenter has been performing the repetitive inspections proposed in the AD. The commenter indicates that accomplishment of these inspections has proven to provide an acceptable level of safety by detecting all cracking before a critical cumulative defect size has been exceeded.

The FAA does not concur with the commenter's request. The FAA finds that the requested change is unnecessary because such credit is provided by the statement in the AD, "Required as indicated, unless accomplished previously." Any operator that has accomplished the required inspections may take credit for those inspections provided that the repetitive inspections are accomplished in accordance with the requirements of this AD.

The same commenter also requests that paragraphs (a)(1) and (b)(1) of the proposed rule be revised to clarify that the modification must be accomplished prior to further flight following the third inspection accomplished after the effective date of the AD. Since the commenter has been conducting theproposed inspections, the FAA infers from this commenter's request that it would like credit for those inspections without having to modify the wheel subassemblies sooner than the AD would require had the operator not conducted any inspections.

The FAA concurs that clarification is necessary, and has revised paragraphs (a)(1) and (b)(1) of the final rule to clarify its intent that the modification must be accomplished prior to further flight following the third inspection accomplished after the effective date of this AD.

This commenter also requests that paragraph (c) of the proposed rule be revised to delete the words "and modified." The commenter points out that wheel subassemblies that are inspected in accordance with the proposal may remain in service until the third inspection after the effective date of the AD, at which time those subassemblies must be modified. Therefore, a wheel subassembly that has been inspected in accordance with the proposed rule would be considered to be safe. The FAA finds that clarification is necessary. Paragraph (c) of the final rule has been revised to specify that certain parts may not be installed on the airplane unless the part has been inspected and subsequently modified in accordance with the requirements of this AD.

The FAA has revised paragraphs (a)(2) and (b)(2) of the final rule to indicate that the replacement procedures required by those paragraphs are found in the Airplane Maintenance Manual. This information was omitted inadvertently from the proposal.

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

The FAA estimates that 87 airplanes of U.S. registry will be affected by this AD, that it will takeapproximately 14 work hours per airplane to accomplish the required actions, and that the average labor rate is $55 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $66,990, or $770 per airplane.

The total 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 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 certifythat 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 39continues 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.

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