98-07-16 BOEING: Amendment 39-10436. Docket 95-NM-207-AD.

Applicability: Model 737-300, -400, and -500 series airplanes having line numbers 1001 through 2791 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 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 (c) 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 adversely affected operation of the fuse, which could result in the loss of all standby hydraulic system pressure and consequent severely reduced controllability of the airplane during certain flight phases, accomplish the following:

(a) For airplanes listed in Boeing Service Bulletin 737-29-1070, dated June 8, 1995: Within 18 months or 4,000 flight hours after the effective date of this AD, whichever occurs later, interchange the location of the hydraulic fuse and the flow limiter of the standby hydraulic system of the leading edge so that the hydraulic fuse is positioned upstream of the flow limiter, in accordance with Boeing Service Bulletin 737-29-1070, dated June 8, 1995.

(b) For airplanes listed in Boeing Service Bulletin 737-29-1071, dated May 16, 1996: Within 18 months or 4,000 flight hours after the effective date of this AD, whichever occurs later, replace the existing hydraulic fuses in the standby hydraulic system with new fuses that are not adversely affected during low temperature operation, in accordance with Boeing Service Bulletin 737-29-1071, dated May 16, 1996.

(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. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

NOTE 2: 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 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.

(e) The actions shall be done in accordance with Boeing Service Bulletin 737-29-1070, dated June 8, 1995, and Boeing Service Bulletin 737-29-1071, dated May 16, 1996. 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 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.

(f) This amendment becomes effective on May 7, 1998.

FOR FURTHER INFORMATION CONTACT:

Kenneth W. Frey, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2673; fax (425) 227-1181.