Airworthiness Directive · Amendment 39-16354 · Nacelles/pylons
The Boeing Company Model 747-100B, 747-200B, 747-200F, 747-300, 747-400, 747-400F, and 747SP Series Airplanes Equipped with Rolls-Royce RB211-524 Series Engines
This AD applies to The Boeing Company Model 747-100B, 747-200B, 747-200F, 747-300, 747-400, 747-400F, and 747SP series airplanes; certificated in any category; equipped with Rolls-Royce RB211-524 series engines; as identified in Boeing Alert Service Bulletin 747-54A2224, Revision 3, dated May 20, 2010.
We are adopting a new airworthiness directive (AD) for certain Model 747-100B, 747-200B, 747-200F, 747-300, 747-400, 747-400F, and 747SP series airplanes. This AD requires repetitive detailed and high frequency eddy current inspections of the forward and aft sides of the strut front spar chord for cracks and fractures at each strut location, and corrective actions if necessary. This AD results from reports of cracks and fractures in the nacelle strut front spar chord assembly. We are issuing this AD to detect and correct cracks and fractures of the nacelle strut front spar chord assembly. Fracture of the front spar chord assembly could lead to loss of the strut upper link load path and consequent fracture of the diagonal brace, which could result in in- flight separation of the strut and engine from 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.
Before the accumulation of 8,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later: Perform a detailed inspection and a high frequency eddy current (HFEC) inspection for cracking or fracturing in the forward and aft sides of the strut front spar chord, in accordance with Parts 1 and 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2224, Revision 3, dated May 20, 2010. If no cracking or fracturing is found, repeat the inspections thereafter at intervals not to exceed 1,500 flight cycles.
If any crack or fracture is found during any inspection required by this AD: Before further flight, repair the crack or fracture using a method approved in accordance with the procedures specified in paragraph (i) of this AD.
