AD 96-19-16

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires inspections to detect cracking of the Hi-lok bolt holes in the main hinge fittings of the horizontal stabilizer, and repair, if necessary. The amendment also requires modification of the main hinge fitting, modification or replacement of rib connecting angles, and modification of ribs. This amendment is prompted by a report indicating that cracking was found in the main hinge fittings of the horizontal stabilizer during fatigue testing. The cracking was a result of higher-than-anticipated loads induced during operation of the thrust reverser. The actions specified by this AD are intended to prevent deterioration of the fatigue life of the main hinge fittings of the horizontal stabilizer and reduced structural integrity of the horizontal stabilizer due to higher induced loads.

Final rule

96-19-16 FOKKER: Amendment 39-9762. Docket 95-NM-59-AD.
Applicability: Model F28 Mark 0100 airplanes; having serial numbers 11244 through 11420 inclusive, 11422, 11424 through 11428 inclusive, 11432 through 11439 inclusive, and 11443 through 11445 inclusive; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 reduced structural integrity of the horizontal stabilizer, accomplish the following:

NOTE 2: Inspections and modifications accomplished prior to the effective date of this amendment in accordance with Fokker Service Bulletin SBF100-55-021, Revision 1, dated September 6, 1993, are considered acceptable for compliance with the inspections and modifications required by this amendment.

(a) Prior to the accumulation of 15,000 total flight cycles, or within 1 year after the effective date of this AD, whichever occurs later: Perform a rotor probe inspection and a pencil probe inspection to detect cracking of the Hi-lok bolt holes in the main hinge fittings of the horizontal stabilizer, in accordance with Part 5 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-55-021, Revision 2, dated December 27, 1993. This inspection is notrequired for airplanes that have been modified as specified in paragraph (b) of this AD, provided that the modification is accomplished prior to the accumulation of 1,000 total flight cycles.

(b) Either prior to the accumulation of 1,000 total flight cycles; or prior to further flight after the inspection required by paragraph (a) of this AD if, as a result of that inspection, no cracking is found, or all cracks that are found are less than or equal to the values specified in the Decision Diagram (Figure 2) of Fokker Service Bulletin SBF100-55-021, Revision 2, dated December 27, 1993: Accomplish the modification requirements specified in paragraph (b)(1) and (b)(2) of this AD.

(1) Modify the main hinge fittings of the horizontal stabilizer; and replace or modify the connecting angles at Rib 215, as applicable; in accordance with Fokker Service Bulletin SBF100-55-021, Revision 2, dated December 27, 1993, and as specified in either paragraph (b)(1)(i) or (b)(1)(ii) of this AD, as applicable.

(i) For airplanes that have accumulated less than 1,000 total flight cycles at the time of modification: Accomplish the modification in accordance with either Part 3 or Part 4 of the Accomplishment Instructions of the service bulletin, as applicable.

(ii) For airplanes that have accumulated 1,000 or more total flight cycles at the time of modification: Accomplish the modification in accordance with either Part 6 or Part 7 of the Accomplishment Instructions of the service bulletin, as applicable.

(2) Modify Rib 215 of the horizontal stabilizer to close the lightening holes in accordance with Part 8 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-55- 021, Revision 2, dated December 27, 1993.

(c) If any cracking is found as a result of the inspection required by paragraph (a) of this AD, and the cracking exceeds the values specified in the Decision Diagram (Figure 2) of Fokker Service Bulletin SBF100-55-021, Revision 2, dated December 27, 1993: Prior to further flight, repair in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate.

(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. 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 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the 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) Theactions shall be done in accordance with Fokker Service Bulletin SBF100-55-021, Revision 2, dated December 27, 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 October 24, 1996.

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 13, 1996 (61 FR 5524). That action proposed to require a rotor probe inspection and a pencil probe inspection to detect cracks of the Hi-lok bolt holes in the main hinge fittings of the horizontal stabilizer. For certain airplanes, that action also proposed to require modification of the Hi-lok bolt holes by cold expansion and stiffening of the ribs at Station 215.

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

Support for the Proposal
One commenter supports the proposed rule.

Request to Extend the Compliance Time
One commenter requests that the compliance time for the initial inspectionbe extended from the proposed 15,000 total flight cycles to 16,000 flight cycles. The commenter considers that extending the compliance time to 16,000 flight cycles would allow an operator to accomplish the inspection during regularly scheduled maintenance, and would prevent any disruption of service. The commenter states that the adoption of the proposed compliance time would require scheduling of special times for the accomplishment of this inspection at considerable expense beyond what was estimated in the cost impact of the proposed rule.

The FAA does not concur. In developing the compliance time for this rulemaking action, the FAA took into consideration not only the safety implications associated with the addressed unsafe condition and the normal maintenance schedules for the majority of affected operators, but also the results of fatigue tests and analysis performed by the manufacturer, the manufacturer s recommended compliance time specified in the applicable service bulletin, and the foreign airworthiness authority s recommended compliance time of 15,000 total flight cycles. In consideration of these factors, the FAA finds that a compliance time of 15,000 total flight cycles (or within 1 year after the effective date of this date) is appropriate and should fall during a time of scheduled maintenance for the majority of affected operators. However, paragraph (d) of the final rule does provide affected operators the opportunity to apply for an adjustment of the compliance time if data are presented to justify such an adjustment.

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 90 airplanes of U.S. registry will be affected by this AD, that it will take approximately 136 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $1,800 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $896,400, or $9,960 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.

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: