The 388th Maintenance Group has announced that five of the US Air Force’s (USAF) ten faulty F-35A Lightning IIs, which were temporarily restricted from flying, have resumed training flights following repairs to their faulty insulation on coolant lines.

Maintainers from the 388th and 419th Fighter Wings are involved in the repair process and also sustain flying operations with a limited number of operational aircraft.

388th Maintenance Group commander Michael Miles said: “This coolant line issue is not preventing us from flying our other aircraft.

“We’re still flying, and exercising combat generations and turning our aircraft.”

The USAF announced in September this year that it decided to repair 57 F-35As that had faulty coating on avionics cooling lines installed in the fuel tank.

The initial repair process involved removal of fuel and panelling from the jets. A field-team of contract maintainers then cut pre-engineered holes in the aircraft skin to access specific points in the fuel tank.

Furthermore, it involved stripping the faulty coating from the coolant lines and installing screens to prevent any foreign object from clogging the fuel siphon-tubes.

After completing the repair work, the aircraft skin and low-observable coating was restored and airmen completed operational checks on the aircraft prior to returning it to service.

"We’re still flying, and exercising combat generations and turning our aircraft."

388th Operations Group commander Jason Rueschhoff said: "With fewer jets to fly, that impacts sorties and training opportunities for pilots.

"But, we've been working closely with Luke AFB, Arizona; Eglin AFB, Florida; and Nellis AFB, Nevada, sending some of our pilots there to use any additional F-35 flying capacity those bases can make available to help maintain our pilots' proficiency."

All ten affected jets are expected to return to service before the end of the year.

Image: The 10 F-35A Lightning II at Hill Air Force Base, Utah. Photo: courtesy of US Air Force.