F-35A The entire F-35 fleet has been grounded after inspections revealed cracks in the Pratt & Whitney F135 engine turbine blade. ...
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| F-35A |
The entire F-35 fleet has been grounded after inspections revealed cracks in the Pratt & Whitney F135 engine turbine blade.
Crack on the 3rd stage low-pressure turbine turbine was found on Feb. 19 during an inspection of a conventional F-35A at Edwards AFB, California.
U.S.Naval Air Systems Command (Navair) said the grounding is to avoid a potential “catastrophic failure.”
The latest crack was discovered only days after the F-35B returned to flight following a 25-day grounding caused by a fueldraulics failure.
The crack was discovered by a borescope inspection on an F-35A and confirmed by an eddy current inspection, engine maker Pratt & Whitney said.
The engine has run a total of around 700 hours, of which 409 hours were flight hours, P&W says.
Though the issue was found in a single engine, there was no clear cause behind the crack. The engine's turbine module has been shipped to P&W's Connecticut test facility for closer inspection.
Two previous incidents with the third stage low pressure turbine blades have resulted in F-35 groundings in the past, once in 2007 and again in 2008.
Those incidents, which both occurred in the F-35B vertical-takeoff variant, were traced to high-cycle fatigue. Unexpected vibration levels were caused by interaction of the the blade with the wakes from vanes upstream of the third-stage turbine.
