Head of Air Combat Command Gen. Herbert Carlisle told lawmakers at a hearing that the service is yet to determine the root cause behind starter-generator failures on MQ-9s.
![151206-F-CX842-148[1]](http://alert5.com/wp-content/uploads/2016/02/151206-F-CX842-1481.jpg)
U.S. Air Force photo by Tech. Sgt. Robert Cloys
Luckily, a backup alternator installed during a crash program has managed to save 17 MQ-19s since last April.
A starter-generator helps to start up the turboprop engine and switches to become an alternator to provide electrical power during flight.
Carlisle added that from Block 5 aircraft onward, a different electrical system is installed on the unmanned aerial vehicle to sidestep the problem.