AD 96-13-06

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 series airplanes, that requires replacement of junction fittings of the horizontal stabilizer with improved fittings. For certain airplanes, this amendment also requires replacement of the drive-fitting bushings and bolts of the horizontal stabilizer with improved bushings and bolts. This amendment is prompted by reports of stress corrosion cracking in a junction fitting lug of the horizontal stabilizer. The actions specified by this AD are intended to prevent such cracking, which could result in failure of a lug and uncommanded movement of the horizontal stabilizer. This condition, if not corrected, could result in reduced controllability of the airplane.

Final rule

96-13-06 FOKKER: Amendment 39-9674. Docket 95-NM-151-AD.
Applicability: Model F28 series airplanes; serial numbers 11003 through 11151 inclusive, 11991, and 11992; certificated in any category.

NOTE 1: Fokker Model F28 Mark 0100 series airplanes are not subject to the requirements of this AD.

NOTE 2: 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 stress corrosion cracking of the junction fitting lug of the horizontal stabilizer, which could result in failure of the lug and uncommanded movement of the horizontal stabilizer, and subsequent reduced controllability of the airplane, accomplish the following:

(a) Within 18 months after the effective date of this AD, replace the aluminum 7079 junction fittings (left and right) of the horizontal stabilizer with improved fittings made from aluminum 7075, in accordance with Part 1 of the Accomplishment Instructions of Fokker Service Bulletin F28/55-029, Revision 1, dated January 23, 1993.

(b) For airplanes on which the drive-fitting bushings and bolts of the horizontal stabilizer have not been replaced in accordance with Fokker Service Bulletin F28/55-24: Within 18 months after the effective date of this AD, replace the drive-fitting bushingsand bolts of the horizontal stabilizer with new bushings and bolts, in accordance with Part 2 of the Accomplishment Instructions of Fokker Service Bulletin F28/55-029, Revision 1, dated January 23, 1993.

(c) Accomplishment of the replacements required by paragraphs (a) and (b) of this AD constitute terminating action for the inspections identified as item 55-50-05 in the Fokker Structural Integrity Program (SIP) Document 28438, Part 1, revised up through October 15, 1992, which are required by AD 93-13-04, amendment 39-8617 (58 FR 38513, July 19, 1993). Once these replacements are accomplished, the life limits of the fitting lugs (identified as items 55-50-01 and 55-50-02 in the SIP Document) no longer apply.

(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 requeststhrough 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) The replacements shall be done in accordance with Fokker Service Bulletin F28/55- 029, Revision 1, dated January 23, 1993, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page
1-3
1
January 23, 1993
4-45
Original
September 20, 1992

This incorporation by reference was approved by the Director of the Federal Register in accordance with5 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 July 26, 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 series airplanes was published in the Federal Register on April 1, 1996 (61 FR 14273). That action proposed to require replacement of aluminum 7079 junction fittings (left and right) of the horizontal stabilizer with improved fittings made from aluminum 7075. For certain airplanes, that action also proposed to require replacement of the drive-fitting bushings and bolts of the horizontal stabilizer with new bushings and bolts made from a different material having improved resistance to corrosion.

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

Support for the Proposal
Both commenters support the proposed rule.

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 14 airplanes of U.S. registry will be affected by this AD.

For airplanes on which the replacement of aluminum 7079 junction fittings with improved fittings is required, the FAA estimates that it will take approximately 430 work hours per airplane to accomplish the replacement, at an average labor rate of $60 per work hour. Required parts will cost approximately $40,000 per airplane. Based on these figures, the cost impact of the AD on U.S. operators for replacement of aluminum 7079 fittings is estimated to be $65,800 per airplane.

For airplanes on which replacement of the drive-fitting bushings and bolts on the horizontal stabilizer with new bushings and bolts is required, the FAA estimates that it will take approximately 10 work hours per airplane to accomplish the replacement, at an average labor rate of $60 per work hour. Required parts will cost approximately $2,100 per airplane. Based on these figures, the cost impact of the AD on U.S. operators for replacement of the drive-fitting bushings and bolts is estimated to be $2,700 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 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: