Worn Part, Faulty Work Down UAVs

According to Air Combat Command accident investigation boards a Predator and Reaper unmanned aerial vehicle crashed because of a quill shaft bearing failure and an improperly assembled oil system temperature control valve, respectively. The MQ-1 Predator that crashed Oct. 19, 2008, just short of Ali Base in Iraq was destroyed upon impact. The failure of its quill shaft bearing caused the UAV’s variable pitch propeller to change pitch leading it to reverse thrust. The bearing apparently had been used “beyond the designed specifications,” according to the ACC release. The MQ-9 Reaper crashed March 20 of this year at Ft. Irwin, Calif., when it suffered “a severe oil flow imbalance which resulted in engine failure,” stated the ACC release. The improper assembly of the aircraft’s oil system temperature control valve caused the oil flow imbalance.