Broken Propeller Component Doomed Predator

Air Combat Command investigators determined that a broken variable-pitch propeller quill shaft caused the crash of an MQ-1B Predator remotely piloted aircraft last August in Afghanistan, announced command officials. The broken quill shaft forced the aircraft’s propeller to an abnormal angle, generating increased drag and causing the aircraft to rapidly descend, according to ACC’s accident investigation board report, released last week. Since the aircraft lost too much altitude, it was unable it reach its forward operating base, so operators attempted to bring it down in a rural, unpopulated area. However, due to its rapid descent rate, it ended up crashing in a civilian residential area, damaging two structures, states the report. The board president also determined that the lack of Air Force maintenance guidance on the quill shaft resulted in it exceeding the manufacturer’s defined serviceable life. The loss of the Predator on Aug. 20, 2011, along with one Hellfire missile and one missile rail, is estimated at about $3.9 million, according to the report. (AIB report; caution, large-sized file.)