Airworthiness Directive · Amendment 39-15233 · Boeing Model 707 Airplanes and Model 720 and 720B Series Airplanes
Boeing Model 707 Airplanes and Model 720 and 720B Series Airplanes
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.
The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 707 airplanes and Model 720 and 720B series airplanes. This AD requires identifying the material used in the elevator hinge support fittings of the horizontal stabilizer trailing edge, doing repetitive detailed inspections for cracking of the fittings and corrective actions if necessary, and doing an eventual terminating action. This AD results from a report that stress corrosion cracking of the elevator hinge support fittings 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.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3518, dated October 9, 2006.
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.
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.
(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.
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.
