Airworthiness Directive · Amendment 39-13807 · Boeing Model 707 and 720 Series Airplanes
Boeing Model 707 and 720 Series Airplanes
All Model 707 and 720 series airplanes, certificated in any category.
This amendment adopts a new airworthiness directive (AD), applicable to all Boeing Model 707 and 720 series airplanes, that requires an inspection of the main landing gear (MLG) lock support fitting and the wing fillet flap support link for damage, and corrective action, if necessary; and replacement of the bolts and bushings at the joint between the MLG lock support fitting and the wing fillet flap support link. This action is necessary to prevent stress corrosion cracking of the bolts and wearing of the joint between the lock support fitting and the support link, which could lead to failure of the joint and could cause the collapse of the MLG. This action is intended to address the identified unsafe condition.
To prevent stress corrosion cracking of the bolts and wearing of the joint between the lock support fitting and the support link, which could lead to failure of the joint and could cause the collapse of the main landing gear (MLG), accomplish the following:
(a) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3511, dated January 23, 2003.
(b) Within 12 months or 1,000 flight cycles after the effective date of this AD, whichever comes first, perform a high frequency eddy current (HFEC) inspection of the MLG lock support fitting and the support link for cracks and corrosion in accordance with the service bulletin.
(c) If any crack or corrosion is found, during the HFEC inspection required by paragraph (b) of this AD, before further flight, rework the lock support fitting or support link, in accordance with the service bulletin, except as specified in paragraphs (c)(1) and (c)(2) of this AD.
(1) If the service bulletin specifies to contact Boeing for rework limits: Before further flight, repair or replace the lock support fitting or support link per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair/replacement method to be approved, the approval must specifically reference this AD.
(2) Where the service bulletin specifies to rework the forward and aft lug bore and faces common to the lock support fitting of the MLG as given in Boeing Service Bulletin 707-2837, this AD requires rework to be accomplished only in accordance with Revision 5 of Boeing 707 Service Bulletin 2837, dated March 31, 1978.
(d) Within 12 months or 1,000 flight cycles after the effective date of this AD, whichever comes first, replace the bolts and bushings at the joint between the lock support fitting for the MLG and the wing fillet flap with new CRES bolts and Cadmium-plated Al-Ni-Br bushings in accordance with the service bulletin.
(e) As of the effective date of this AD, only bolts specified in paragraph (e)(1) of this AD and bushings specified in paragraph (e)(2) of this AD, may be installed at the joint between the MLG lock support fitting and the support link, on any airplane.
(1) CRES bolts, part number (P/N) BACB30LR10DK56 or P/N BACB30LR10DK62.
(2) Cadmium-plated aluminum nickel bronze bushings as specified in the service bulletin.
(f) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, FAA, is authorized to approve alternative methods of compliance for this AD.
(g) Unless otherwise specified in this AD, the actions shall be done in accordance with Boeing 707 Alert Service Bulletin A3511, dated January 23, 2003. 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 Airplanes, 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 National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
