The Pentagon’s top weapons buyer is backing calls to restore a valve on Lockheed Martin Corp.’s F-35 jet that improves the fighter’s chances to survive a hit from a high-explosive round.
“The addition of an improved” valve “would result in the aircraft being fully compliant” with its operational requirements, Frank Kendall, the under secretary for acquisition, wrote a lawmaker last month in a previously undisclosed letter.
The two-pound valve system was part of 43 pounds (20 kilograms) of equipment removed in 2008 to save weight on the F-35, the Pentagon’s most expensive weapons program. The valve is intended to shut off the flow of a flammable liquid used to cool avionics.
Computer analysis of the pared-down F-35 design last year determined that the aircraft’s vulnerability to fires ignited by enemy bullets or missile fragments increased 25 percent from an assessment before the equipment’s removal, according to data from the Pentagon’s weapons-testing office.
Questions about the aircraft’s vulnerability in combat are among those surrounding the $395.7 billion program, which has increased in estimated cost by 70 percent since 2001.
Pentagon and congressional supporters have stood by the plane as it has weathered production flaws, aircraft delivery and software delays, bulkhead cracks, groundings and sour relations between the Pentagon’s program office and Bethesda, Maryland-based Lockheed.
The program has yet to deliver an aircraft with a durable tailhook for carrier landings, a helmet that gives pilots undistorted images and software that will operate all combat systems.
Every aircraft has vulnerable areas that could disable or destroy an engine, fuel tank or the pilot if hit by a bullet or fragment. Testing is intended to calculate which areas are vulnerable and the likelihood of a hit. The F-35 analysis assessed the jet’s vulnerability to an onboard fire.
The shutoff valve removed in 2008 was designed to prevent a fire by detecting leakage of liquid used to cool the F-35’s computerized avionics and stopping the flow from a damaged fuel line.
The Pentagon’s F-35 program office and Lockheed Martin are in the preliminary stages of reviewing an improved valve, which is a “technically challenging activity,” Kendall wrote.
A final decision will be made by the Air Force, Navy, Marine Corps and international purchasers that will fly the aircraft, Kendall wrote Representative James Moran, a Virginia Democrat who serves on the House defense appropriations subcommittee and has insisted on restoration of the safety equipment.
Even without the valve, the F-35 design is “far more survivable than any of the legacy tactical aircraft we have ever fielded,” Kendall wrote. The F-35 is replacing the F-16, A-10 Thunderbolt, F-18A/C/D models and AV-8B Harrier aircraft.
“The combination of stealth, data fusion, advanced sensors, advanced countermeasures and electronic attack” greatly reduce the chances the aircraft will be hit by enemy fire, Kendall wrote.
Kendall said the test office conclusion that vulnerability increased 25 percent focused on a small area “assuming that the aircraft is hit.” The probability “is actually a small, classified number,” Kendall wrote. This means “the overall impact to aircraft survivability is small, less than 0.5 percent,” he said.
The F-35 program office and the Government Accountability Office have cited recent improvements in the plane.
Lockheed’s performance since a strike of its aerospace workers ended in July “has been fairly stable and the program has seen marked improvement in design stability,” Air Force Lieutenant General Christopher Bogdan, the program manager, told a Senate Armed Services Committee panel April 25.
The GAO, the watchdog agency for Congress, reported in March that the fighter’s “current outlook is improved but long-term affordability is a major concern.”
“Overall, the F-35 Joint Strike Fighter program is moving in the right direction after a long, expensive and arduous learning period,” the GAO said. “It still has tremendous challenges ahead.”
Kendall’s letter fits that theme of improvement. Last year, he said putting the aircraft into production while development testing was beginning constituted “acquisition malpractice.”
He told reporters last month, “I feel much more comfortable” now about the F-35.