AD 90-12-04 R1

90-12-04 R1 BOEING: Amendment 39-8668. Docket 93-NM-43-AD. Revises AD 90-12-04, Amendment 39-6621 which superseded AD 88-01-08, Amendment 39-5827.

Applicability: Model 757 series airplanes, listed in Boeing Alert Service Bulletin 757-30A0013, Revision 6, dated March 25, 1993, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent undetected failure of the anti-ice system which could ultimately result in unacceptable ice build-up on the wings or engine inlets, accomplish the following:

(a) For airplanes listed in Boeing Alert Service Bulletin 757-30A0013, Revision 5, dated September 7, 1989: Accomplish the requirements of paragraphs (a)(1) and (a)(2) of this AD.

(1) Within the next 300 hours time-in-service after February 4, 1988 (the effective date of AD 88-01-08, Amendment 39-5827), perform a functional test of the wing and engine cowl anti-ice control and indication system, in accordance with Section III, Part I of Boeing Alert Service Bulletin 757- 30A0013, Revision 5, dated September 7, 1989. Repeat this functional test thereafter at intervals not to exceed 300 hours time-in-service until the modification required by paragraph (a)(2) of this AD is accomplished.

NOTE 1: Paragraph (a)(1) of this AD restates the requirements of AD 88-01-08, Amendment 39-5827, paragraph A. As allowed by the phrase, "unless accomplished previously," if the requirements of AD 88-01-08 have been accomplished previously, paragraph (a)(1) of this AD does not require that the initial inspection be repeated.

(2) Within the next 3,000 hours time-in-service after July 9, 1990 (the effective date of AD 90-12-04, Amendment 39-6621), modify and test the wing and engine cowl anti-ice control and indication system in accordance with Section III, Parts II, III, IV, V, VI, and VII, as applicable, of Boeing Alert Service Bulletin 757-30A0013, Revision 5, dated September 7, 1989; or Section III, Parts II, III, IV, V, VI, VII, and VIII, as applicable, of Revision 6, dated March 25, 1993. Accomplishment of this modification constitutes terminating action for the repetitive testing requirement of paragraph (a)(1) of this AD.

NOTE 2: Paragraph (a)(2) of this AD restates the requirements of AD 90-12-04, Amendment 39-6621, paragraph B. As allowed by the phrase, "unless accomplished previously," if the requirements of AD 90-12-04 have been accomplished previously, paragraph (a)(2) of this AD does not require that the modification be repeated.

(b) For airplanes listed in Boeing Alert Service Bulletin 757-30A0013, Revision 6, dated March 25, 1993, that are not subject to paragraph (a) of this AD: Accomplish the requirements of paragraphs (b)(1) and (b)(2) of this AD.

(1) Within the next 300 hours time-in-service after the effective date of this AD, perform a functional test of the wing and engine cowl anti-ice control and indication system, in accordance with Section III, Part I, of Boeing Alert Service Bulletin 757-30A0013, Revision 6, dated March 25, 1993. Repeat this functional test thereafter at intervals not to exceed 300 hours time-in-service until the modification required by paragraph (b)(2) of this AD is accomplished.

(2) Within the next 3,000 hours time-in-service after the effective date of this AD, modify and test the wing and engine cowl anti-ice control and indication system in accordance with Section III, Parts II, III, IV, V, VI, VII, and VIII, as applicable, of Boeing Alert Service Bulletin 757-30A0013, Revision 6, dated March 25, 1993. Accomplishment of this modification constitutes terminating action for the repetitive testing requirement of paragraph (b)(1) of this AD.

(c) 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, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operatorsshall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(d) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) The tests and modifications shall be done in accordance with Boeing Alert Service Bulletin 757-30A0013, Revision 5, dated September 7, 1989, or Boeing Alert Service Bulletin 757-30A0013, Revision 6, dated March 25, 1993, 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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may beinspected 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.

(f) This amendment becomes effective on October 13, 1993.