The new details, released late last month by Air Combat Command, revealed some of the circumstances that caused the ...

The US Air Force found that the costly mishap was caused by an unexplained failure in the part connecting the drone's engine ...

The drone's crew, flying from a base in Missouri, tried to regain control of the MQ-9A Reaper as it flew over the ...

Most likely, the report said, the specific cause was a Spiral Retaining Ring, a part with a history of rapid wear in the Reaper’s engine.

The standard material for spiral-wound retaining rings is carbon spring steel. Some rings are available in other materials such as 302, 316, and 17-7 PH/C stainless steel, NS A286 alloy, beryllium ...

Here, the replacement spiral ring fits into the preexisting groove. Three alternatives to traditional retainers are retaining rings, spiral rings, and wave springs.