The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 757-200 and -200PF series airplanes; and Model 767-200 and -300 series airplanes. This proposed AD would require doing an inspection to determine the part number and serial number of the hub assembly of the ram air turbine (RAT), and replacing the hub assembly of the RAT with a new, serviceable, or reworked and re-identified hub assembly if necessary. This proposed AD results from reports indicating that the counterweights in some hub assemblies of the RATs could be under strength and fracture when they are extended in flight. We are proposing this AD to prevent a fractured counterweight on the hub assembly of the RAT, which will cause an overspeed condition, and consequent turbine blade separation, possible injury to passengers, possible airplane structural damage, and an inoperative RAT. An inoperative RAT will cause the loss of hydraulic power to the primary flight controls in cases where both engines are shut down in flight, resulting in subsequent loss of control of the airplane.
Agency Contact: Kenneth Frey, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057- 3356; telephone (425) 917-6468; fax (425) 917-6590.
This is a proposed regulation. Comments were due on July 7, 2008.