AD 2007-21-15 Airworthiness Directives; Boeing Model 707 Airplanes and Model 720 and 720B Series Airplanes

Models named: 707-100 long body, -200, -100B long body, -100B short body series, 707-300, -300B, -300C, -400 series, 720, 720B series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to all Model 707-100 long body, -200, -100B long body, and -100B short body series airplanes; Model 707-300, -300B, -300C, and -400 series airplanes; and Model 720 and 720B series airplanes; certificated in any category.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Service Bulletin Reference (f) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3518, dated October 9, 2006. Material Identification (g) Within 180 days after the effective date of this AD or before further flight after any horizontal stabilizer is replaced: Verify the type of material used in the elevator hinge support fittings of the horizontal stabilizer trailing edge, in accordance with Part 1 of the Accomplishment Instructions of the service bulletin, then do the requirements of paragraph (g)(1) or (g)(2) of this AD, as applicable. Repeat the verification before further flight after the replacement of any hinge support fitting. (1) For any hinge support fitting made of 7075-T7351 material: No further action is required by paragraph (h) or (i) of this AD. (2) For any hinge support fitting made of 7079-T6 or 7075-T6 material: Do the actions required by paragraph (h) of this AD. Repetitive Inspections, One-time Modification, and Corrective Actions (h) Before further flight after doing paragraph (g) of this AD, do a detailed inspection for cracking of the hinge support fittings and modify certain segments of the rib webs, in accordance with Part 2 of the Accomplishment Instructions of the service bulletin. For any hinge support fitting found to be cracked or damaged, before further flight, do the actions required by paragraph (h)(1) or (h)(2) of this AD; in accordance with Part 3 of the Accomplishment Instructions of the service bulletin. Do all actions in accordance with the Accomplishment Instructions of the service bulletin; except where the service bulletin specifies to contact the manufacturer for repair procedures, this AD requires repair using a method approved in accordance with the procedures specified in paragraph (k) of this AD. (1) Replace the fitting with a serviceable fitting made of 7079-T6 or 7075-T6 material. Repeat the detailed inspection thereafter at intervals not to exceed 180 days, until the terminating action required by paragraph (i) of this AD has been done. (2) Replace the fitting with a new, improved fitting made of 7075-T7351 material. Terminating Action (i) For all airplanes: Within 48 months after the effective date of this AD, replace all hinge support fittings made of 7079-T6 or 7075-T6 material with new, improved fittings made of 7075-T7351 material, in accordance with Part 4 of the Accomplishment Instructions of the service bulletin. Doing this action terminates all requirements of paragraphs (g) and (h) of this AD. Parts Installation (j) As of the effective date of this AD, no person may install, on any airplane, a new or serviceable hinge support fitting made of 7079-T6 or 7075-T6 material, unless the requirements of paragraph (h)(1) of this AD are accomplished. Alternative Methods of Compliance (AMOCs) (k)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. (2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. (3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane and the approval must specifically refer to this AD. Material Incorporated by Reference (l) You must use Boeing 707 Alert Service Bulletin A3518, dated October 9, 2006, to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for a copy of this service information. You may review copies 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/cfr/ibr-locations.html. Issued in Renton, Washington, on October 5, 2007. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E7-20219 Filed 10-15-07; 8:45 am] BILLING CODE 4910-13-P

This AD results from a report that stress corrosion cracking of the elevator hinge support fittings of the horizontal stabilizer trailing edge has been discovered on several Model 707 airplanes. We are issuing this AD to prevent cracking of the elevator hinge support fittings, which could reduce the elevator support stiffness and lead to in-flight airframe vibration, consequent damage to the elevator and horizontal stabilizer, and reduced controllability of the airplane.