F-35 Engines - Devil is in the Detail Parts

For Pratt it was a bushing. For GE/Rolls, it seems, it's a lug. In both cases testing of engines for the F-35 Joint Strike Fighter has been affected [see note] by failures caused by minor components - perhaps illustrating how hard it is to develop a high-performance jet engine.

The General Electric/Rolls-Royce Fighter Engine Team, which halted testing of the F136 alternate engine on Oct. 2 after finding "dings and nicks" on turbine blades, has traced the damage to a tiny lug coming loose on the diffuser, which directs air into the combustor.

"A diffuser component which connects the diffuser to the combustor will be modified," says GE/R-R. "We expect to have an F136 test engine running before year's end." With only 52 hours accumulated since the first SDD engine ran in January, that could mean the loss of almost three months of ground testing.

Pratt & Whitney, meanwhile, announced in September it would modify the first-stage fan blades on production F135 primary engines after a humble worn bushing in the fan inlet case caused an aerodynamic disturbance that led to a piece of the blade tip breaking off during engine durability testing. 

[NOTE: I originally wrote "halted", but Pratt says that, other than the affected engine, F135 testing continued while it determined the cause of the fan damage, and delivery of initial production engines was not delayed.]

Tags: ar99, F136, F-35