The F-35 joint program executive officer (PEO) is confident that the program office has found a solution to software stability problems that induced the plane’s sensors to shut off more frequently than is acceptable, he said Tuesday.
Last month F-35 PEO Air Force Lt. Gen. Christopher Bogdan told lawmakers about instability in the Joint Strike Fighter’s block 3i software, which is caused when miscommunications between the aircraft’s computers and sensors build up, eventually triggering the sensor to restart mid-flight.
Now, after implementing fixes to the software and flying 44 sorties and 96 flight hours, the software is showing a marked improvement, Bogdan said to reporters after a Senate Armed Services Committee hearing on April 26. The aircraft previously experienced one software instability incident—such as an automatic shut down, or having to manually restart a sensor—every three to four hours. Now those incidents occur only about once every 15 hours, much higher than the eight- to 10-hour target.
“We’ve seen stability problems with our block 3i software, however we believe we’ve identified the root cause of these problems and tested solutions in lab and in flight test and are now completing our flight test with these solutions,” he told lawmakers during the hearing. “Our initial indications of these flight testing are positive and we’ve see software stability improve to two to three times better than what we’ve seen in the past. By the end of this month I am encouraged that we will have enough data to consider this problem and issue closed.”
In fact, Bogdan said tests of the fixes will conclude this week. He will make a decision by Friday on whether to incorporate that version of the 3i software ahead of the Air Force’s initial operational capability, scheduled to occur as early as August.
“I’m leaning toward….that’s going to be the version of software that the Air Force declares IOC with,” he said. “That will be the version of software that we retrofit all the block 3 airplanes with.”
It’s not uncommon for sensors in both legacy and modern planes to automatically restart after a period of time, but when that issue becomes frequent, it could impact the pilot’s ability to respond quickly during a mission, Bogdan has said (Defense Daily, March 23).
Most of the improvements to the software were generated by industry, namely prime contractor Lockheed Martin [LMT] as well as subcontractors Northrop Grumman [NOC] and BAE Systems, he said. A “red team” comprised of Air Force, Navy and academia personnel not affiliated with the F-35 program were also tasked to investigate the instability issue.
In his written statement to SASC, the Pentagon’s chief weapons tester Michael Gilmore said the new version of 3i software appears to have shown improvement, although analysis of the test data continues.
However, he said, the F-35 continues to have instability issues before takeoff that often require the aircraft to be restarted.
“During the first 30 flights with Block 3iR6.21, which accumulated 75.6 hours of flight time, no less than 27 power cycles were required to get all systems functioning between initial startup and takeoff,” he wrote. “These power cycles varied in degree—from “cold iron” resets, where the aircraft had to be shut down and then restarted, to component or battery recycling.”
That data, while correct, does not include the latest test flights, said Bogdan, who added that the program office continues to investigate the issue.
“That will be part of the future fixes, if we need them, but right now the warfighter tells us ‘We can handle that. That’s not a big deal,’” he said. “It’s when we get to the runway and we take off and we’re going on our mission, that’s when we need this system to be reliable.”
The red team chartered to look at in-flight instability will also assess the start up issues with the jet, but it will be “another month or two” before Bogdan receives information about the root cause, he said.
The group was charged “to look at the startup cycle for the F35 and are different units doing it differently. Is there a best way to start the airplane up so it gets a clean start?”