A report on the crash said the reason for the break remains unclear but the blade could have been hit by a screw or some similar object, Ynetnews.com reported. Investigators said neither pilot error nor the age of the Cobra helicopter were responsible for the crash.
Lt. Col. Noam Ron, 49, and Maj. Erez Flekser, 31, were killed last month when the helicopter came down.
The air force grounded all its Cobra helicopters after the crash. After receiving the report, Maj. Gen. Amir Eshel, commander of the air force, ordered Cobras returned to operations.