The fleet of F-35 JSF test aircraft has been grounded for several days following the discovery of a software glitch which could cause a fuel boost pump to shut down in flight.
Pentagon spokesman Cheryl Irwin said the software glitch, “could have possibly triggered a shutdown on the three boost pumps, which could potentially cause an engine stall,” and that, “prudence dictated a suspension of operations, temporarily, until the fuel boost pump signal timing was corrected.”
The software issue, which had previously restricted the test fleet from operating above 10,000 feet, adds to a problem with the auxiliary inlet door hinges on the F-35B STOVL test aircraft which had been hindering vertical and short take off and landing flight tests and added to delays in the STOVL test schedule.
The grounding is expected to last until October 6 by which time a software patch will have been developed and uploaded to the aircraft. But the auxiliary inlet hinge issue is a larger one, especially as the four STOVL test aircraft which have flown to date are expected to have achieved at least 50 vertical landings by the end of this calendar year in order for shipborne trials to commence in March 2011. Lockheed Martin test pilot Jon Beesley revealed to Australian media in August that the hinges would require a “beefing up” because of aerodynamic disturbance coming off the large lift fan inlet door immediately in front of the auxiliary inlet during forward flight.