1 RULES and REGULATIONS

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

(Docket No. 91

- NM

- 214

- AD; Amendment 39

- 8129; AD 91

- 22

- 51)

Airworthiness Directives; Boeing Model 757 Series Airplanes

Thursday, January 9, 1992

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

SUMMARY: This action publishes in the Federal Register an amendment adopting Airworthiness Directive (AD)
91

- 22

- 51, which was made effective previously to all known U.S. owners and o perators of Boeing Model 757 series airplanes by individual telegrams. This AD requires repetitive inspections to detect delamination of or physical damage to the trailing edge wedges on the leading edge wing slats, and repair, if necessary. This amendment is prompted by reports of skin separation on trailing edge wedges on wing leading edge slats. The actions specified by this AD are intended to prevent separation of one or more of the trailing edge wedges from the airplane, which could adversely affect th e controllability of the airplane.

DATES: Effective January 24, 1992, to all persons except those persons to whom it was made immediately effective by telegraphic AD T91

- 22

- 51, issued October 17, 1991, which contained this amendment.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of January 24, 1992.

ADDRESSES: The applicable service information may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Se attle, Washington 98124

- 2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the Office of the Federal Register, 1100 L Street NW., Room 8401, Washington, DC.

FOR FURTHER INFORM ATION CONTACT:Thomas Rodriguez, Aerospace Engineer, Airframe Branch,
ANM

- 120S, Seattle Aircraft Certification Office, FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington 98055

- 4056; telephone (206) 227

- 2779.

SUPPLEMENTARY INFORMATION: On October 17, 1991, the FAA issued telegraphic AD T91

- 22

- 51, applicable to Boeing Model 757 series airplanes, which requires repetitive inspections to detect delamination of or physical2 damage to the trailing edge wedges on the leading edge wing slats, and repair, if necessary. That action was prompted by reports from four operators of indications of skin separation of the upper skin on the forward part of the trailing edge wedge on a wing leading edge slats on five Model 757 ser ies airplanes. On two of the slats, inboard pieces of the upper skin were lost from the wedge. This condition, if not corrected, could result in separation of one or more of trailing edge wedges from the airplane, which could adversely affect controllabili ty of the airplane.

The FAA reviewed and approved Boeing Alert Service Bulletin 757

- 57A0045, dated October 16, 1991, which d escribes procedures for a close detailed visual inspection, followed by repetitive detailed visual and “coin

- tap” i nspections, of the trailing edge wedges on the wing leading edge slats to detect delamination and physical damage.

Since the unsafe condition described is likely to exist or develop on other airplanes of the same type design, the FAA issued telegraphic AD T91

- 22

- 51 to require repetitive close visual and “coin tap” inspections of the trailing edge wedges on the wing leading edge slats to detect delamination and physical damage. The required inspections are to be accomplished in accordance with the alert serv ice bulletin previously described. If damage or defective parts are found, they must be repaired in accordance with an FAA

- approved procedure or replaced with new parts.

Since it was found that immediate corrective action was required, notice and public p rocedure thereon were impra cticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual telegrams issued on October 17, 1991, to all known U.S. owners and operators of Boeing Model 757 series airpl anes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to § 39.13 of part 39 of the Federal Aviation Regulations (FAR) to make it effective to all persons.

This is considered to be interim action until t he manufacturer develops non

- destructive inspection (NDI) procedures, at which time the FAA may consider further rulemaking.

The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national go vernment 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 implication s to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation and that it is not considered to be major under
Executive Order 12291. It is impracticable for the agency to follow the proced ures of Order 12291 with respect to this rule since the rule must be issued immediately to correct an unsafe condition in aircraft. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedure s (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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.3 Adoption of the Amendment

Acc ordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 of the Federal Aviation Regulations as follows:

PART 39

— (AMENDED)1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 1354(a), 1421 and 1423 ; 49 U.S.C. 106(g); an d 14 CFR 11.89.

14 CFR § 39.13

§ 39.13 (Amended)

14 CFR § 39.13

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

91

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- 51. Boeing: Amendment 39

- 8129.Docket 91

- NM

- 214

- AD.

Applicability: Model 757 series airplanes, line numbers 140 through 335, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent the separation of the trailing edge wedges from the airplane, accomplish the following:

(a) Perform a close detailed visual inspection of the trailing edge wedges of slats 1 through 4 and 7 through 10, for delamination and physical damage in accordance with Boeing Alert Service Bulletin 757

- 57A0045, dated October 16, 1991, at the times specified below:

(1) For airplanes that have accumulated 5,000 or more flight hours as of the effective date of this AD: Within the next 10 calendar days after the effective date of this AD, and thereafter at intervals not to exceed 300 flight hours.

(2) For airplanes that have accumulated less than 5,000 flight hours as of the effective date of this AD: Within the next 300 flight hours after the effective date of this AD, and thereafter at intervals not to exceed 300 flight hours.

(b) Within the next 300 flight hours after the effective date of this AD, perform a “coin

- tap” inspection of the trailing edge wedges of slats 1 through 4 and 7 through 10 for delamination and physical damage, in accordance with Boeing
Alert Service Bulletin 757

- 57A0045, dated October 16, 1991. Repeat this inspection at intervals not to exceed 1,500 flight hours.4 (c) If delamination and/or physical dama ge are found as a result of the inspections required by paragraph (a) or (b) of this AD, prior to further flight, repair in accordance with an FAA

- approved procedure or replace with new parts. If a repair is accomplished or if new parts are installed, the inspections required by paragraphs (a) and (b) of this AD must
be continued.

(d) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Airc raft Certification Office (ACO), FAA, Transport Airplane Directorate.

Note: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or co mment and then send it to the Manager, Seattle ACO.

(e) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

(f) The inspections required by this AD shall be done in accordance with Boeing Alert Service Bulletin 757

- 57A0045, dated October 16, 1991. 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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washin gton 98124

- 2207. Copies may be inspected at the FAA, Transport Ai r plane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the Office of the Federal Register, 1100 L Street NW., room 8401, Washington, DC.

(g) This amendment (39

- 8129), AD 91

- 22

- 5 1, becomes effective January 24, 1992, to all persons except those persons to whom it was made immediately effective by telegraphic AD T91

- 22

- 51, issued October 17, 1991, which contained the requirements of this amendment.

Issued in Renton, Washington, on December 18, 1991.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

57 FR 781