MQ-1B PREDATOR ACCIDENT REPORT RELEASED Published July 13, 2009 Air Combat Command Public Affairs LANGLEY AIR FORCE BASE, Va. -- A quill shaft bearing failure caused the crash of an MQ-1B Predator just short of Ali Air Base, Iraq, Oct. 19, 2008, according to an Air Combat Command Accident Investigation Board report released today. The $3.7 million Predator, assigned to the 432nd Wing at Creech Air Force Base, Nev., was destroyed upon impact. There were no injuries or damage to other property or equipment. The accident was caused by a quill shaft bearing failure which caused the variable pitch propeller to change pitch during flight to the point of producing reverse thrust. The quill shaft bearing failure was attributed to the use of a worn bearing installation tool worn used beyond the designed specifications during installation. The quill shaft is the control shaft for the variable pitch propeller. Moving the quill shaft inward or outward changes the pitch of the propeller blade, thereby changing the amount of thrust provided. A variable pitch propeller adjusts an aircraft to the pitch of the propeller during flight in order to maximize efficiency. For more information, please contact Air Combat Command Public Affairs at (757) 764-5007 or e-mail accpa.operations@langley.af.mil.