Air Force grounds 15 ‘combat-ready’ F-35s over coolant line flaws

Seven weeks after the Air Force declared its first F-35 jets combat ready, 15 aircraft have been temporarily grounded after service mechanics discovered “peeling and crumbling” insulation wrapped around lines that carry liquid to cool combat systems and computers.

The poor insulation is suspected on 57 aircraft, including 42 still on Lockheed Martin’s Fort Worth production line. The issue is not a design flaw with the aircraft but instead a result of manufacturing quality glitches with one of two subcontractors that make the 18 lines through which the coolant flows, according to an Air Force statement and an interview with a service official, who asked not to be identified.

If not fixed, the crumbling insulation could become lodged in the lines connecting the aircraft’s wing and fuselage fuel tanks causing potential overpressure or underpressure that “may cause structural damage to the fuel tanks,” according to a statement sent Friday to House and Senate defense committees.

“The issue was discovered during depot modification” of an Air Force jet and has resulted this month in a “temporary pause in flight operations,” according to a separate statement from the service.

Ten of the 15 aircraft not flying are located at Hill Air Force Base, Utah, home of the service’s first combat- ready squadron. Two aircraft delivered for Norway are also not flying, said the official.

In a statement, Lockheed Martin said “the issue is confined to one supplier source and one batch of parts.” The company declined to identify the supplier.

“This is not a technical or design issue, it is supply chain manufacturing quality issue,” the company said in its statement. “It will likely require depot-level maintenance to address the corrective actions for the 15 jets in the field. The U.S. Government and Industry engineering teams are analyzing the best approach to resolve this issue. For the 42 F-35As in assembly, the issue will be addressed prior to their delivery.”

Fourteen of the aircraft that need to be fixed on the production line belong to Norway, Italy, Japan, and Israel, according to Air Force data.

The Air Force has taken delivery of 100 F-35A models but the Pentagon’s Defense Contract Management Agency has suspended delivery of additional aircraft “until corrective actions” are in place, according to the Air Force statement.

“Lockheed Martin has begun developing the repair process for these aircraft,” the Air Force statement said.

The official, who follows the F-35 program closely, said the Air Force, Lockheed Martin and the Pentagon program office know precisely which planes have the suspect insulation, so the overall program impact is not widespread.

Still, it’s unknown at this point how long the aircraft will be grounded and when the 42 aircraft currently on Lockheed Martin’s production line will be modified with new insulation, the official said. Air Force and Lockheed engineers should finalize a formal recovery plan by next week, the official said.

This story was originally published September 16, 2016 at 2:22 PM with the headline "Air Force grounds 15 ‘combat-ready’ F-35s over coolant line flaws."