Airworthiness Directive · Amendment 39-16950 · Flight controls
The Boeing Company Airplanes
This AD applies to all The Boeing Company Model 747SP series airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for all Model 747SP series airplanes. This AD was prompted by a report of a rudder hard-over event on a Model 747-400 series airplane, caused by a rudder power control module (PCM) manifold cracking and separating in the area of the yaw damper cavity end-cap. This condition could result in a hard-over of the rudder surface leading to an increase in pilot workload and a possible high-speed runway excursion upon landing, in the event of failure of the lower or upper rudder PCM manifold. This AD requires replacing or modifying the upper and lower rudder PCMs. We are issuing this AD to correct the unsafe condition on these products.
Within 24 months or 8,400 flight hours after the effective date of this AD, whichever occurs first, do the replacement specified in paragraph (g)(1) of this AD or the modification specified in paragraph (g)(2) of this AD for the upper and lower rudder PCMs, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-27A2497, dated September 30, 2010.
(1) Replace any rudder PCM having Boeing part number (P/N) 60B80093-3 (Parker P/N 241700-1005) or Boeing P/N 60B80093-4 (Parker P/N 241700-1007) with rudder PCM having Boeing P/N 60B80093-104 (Parker P/N 241700-9007).
(2) Modify any rudder PCM having Boeing P/N 60B80093-3 (Parker P/N 241700-1005) or Boeing P/N 60B80093-4 (Parker P/N 241700-1007).
Note 1 to paragraph (g): Boeing Alert Service Bulletin 747-27A2497, dated September 30, 2010, refers to Parker Service Bulletin 241700-27-333, dated January 26, 2010, as an additional source of guidance for modifying the upper and lower rudder PCM manifold access caps provided in Option 2 of Work Packages 1 and 2 of Boeing Alert Service Bulletin 747-27A2497, dated September 30, 2010.
As of the effective date of this AD, no person may install a rudder PCM having Boeing P/N 60B80093-3 (Parker P/N 241700-1005) or Boeing P/N 60B80093-4 (Parker P/N 241700-1007), on any airplane.
