Pratt & Whitney Pushes Back on Two Critical F-35 Engine Reports
By Stew Magnuson
Joint strike fighter engine manufacturer Pratt & Whitney said two recent reports by government watchdogs that were critical of its performance on the F135 program are accurate but don’t tell the whole story.
A Government Accountability Office report released April 14 said, “Poor reliability with the [F135] engine has limited the program’s overall reliability progress.” That report was followed April 27 with the Defense Department inspector general’s unfavorable findings on Pratt & Whitney’s quality management system. The IG found 61 violations of regulatory requirements and Defense Department policies.
“The program has a long way to go to achieve its engine reliability goals,’ the GAO report said. “Currently, the F-35 engine’s reliability is very poor and overall aircraft reliability growth has been limited. Improving engine reliability will likely require additional design changes and retrofits.”
Pratt & Whitney’s President of Military Engines Bennett Croswell said he was surprised by the GAO report’s conclusions. “The data that was in the report was accurate. I don’t think it gave a full picture,” he told reporters April 27.
The mean flight hours between failure for the F-35A engine is about 21 percent of where the engine was expected to be at this point in the program, GAO said. As for the short-takeoff/vertical landing B-engine, it is about 52 percent of where the engine was expected to be at this point. “This means that the engine is failing at a much greater rate and requiring more maintenance than expected,” GAO said. The data in the GAO report was taken from the end of the third quarter in 2014.
Croswell said that failure is measured by the breaking of any component down to the smallest sensor. The vast majority of these components can be easily replaced.
The “meantime of engine removal” is a better indicator of how the program is doing, Croswell said. That involves significant maintenance and downtime that takes an aircraft out of service. The data on that is “really good,” he said.
The configuration that Pratt & Whitney currently has, which includes all the necessary fixes to components identified so far, would put the program on track for full maturity by the 2020 deadline, he said. Engines currently being manufactured have these fixes, while those operating on F-35s need to be retrofitted, he said.
The current configuration has been validated by engine testing and bench testing, he added. “We’ve done durability tests on most components,” he said.
The engine program will be considered mature when it exceeds 200,000 flight hours, or each of the three variant engines has more than 50,000 flight hours.
“We will be below the curve for quite some time before we get the entire fleet retrofitted,” he said. That is why he took exception to GAO saying the program has a long way to go. “If the whole fleet had that configuration, we would be right on the curve,” he said.
As for the IG report, Croswell noted that it “doesn’t speak to the quality of our product,” but rather the system of maintaining quality control. Of the 61 violations, 52 were the fault of Pratt & Whitney, Croswell said. Thirty-three were considered “major” violations and 19 “minor.” An example of a major violation was one working failing to wear a face shield, he added.
“We always strive to be better in the area of quality, but we believe, too, that we have a world-class quality system. It is compliant to all the military industrial standards,” Croswell said.
Ten of the major violations were related to software quality assurance. Croswell said prime contractor Lockheed Martin’s software quality assurance was robust and there had never been a major category 1 or category 2 mistake related to software. Two of the IG’s major recommendations were on quality assurance procedures that didn’t follow Defense Department norms. However, Pratt & Whitney had previously negotiated with the F-35 joint program office to do these procedures differently, he said.
The F-35 JPO released a statement April 27 backing up some of the manufacturer’s assertions. “The report is factually accurate; however, the JPO does not agree with all of the findings and recommendations outlined in the report,” it said.
In total, the DoD IG report included six findings and 13 recommendations. Of the six findings, the JPO disagreed with three of them: including the one on software quality management. “In these three cases, the JPO believes the DoD IG findings and recommendations for corrective action are unnecessary, and, if implemented, would add cost and schedule growth to the program for items that are already well understood and carefully managed,” the statement said.
Crowell urged Congress to fully fund a proposed engine component improvement program, which allows military aviation engine companies to modify and improve existing engines, he said. Pratt & Whitney would like to use those funds to expand the F135 engine’s life by 50 percent, he added.Back to Top