Jun 21, 2014
Some F-35s grounded as engine oil leak probed
The onboard fault detection system alerted the pilot of the US Marine Corps F-35B of a fuel loss, prompting the pilot to return to a base in Yuma, Arizona, safely.
A root cause analysis is continuing, but the source of the oil leak in the Pratt & Whitney F135 engine “appears” to be a supply line to bearings and a special fitting within a device called the oil flow managing valve.
The bearings and the fitting “separated from the body” of the valve.
Three days later, the programme ordered all other F-35s grounded until inspectors could examine the same valve. The 90min inspection revealed three “suspect findings” on other F-35Bs at Yuma, but cleared the rest of the fleet to return to flight status.
A metric for F135 engine availability has been steadily at or above 98%.
The Yuma incident follows two other malfunctions within the last 18 months involving the F135 engine, including a cracked low-pressture turbine blade discovered early last year and a cracked fan blade on a test engine last December.