Posted on 06/09/2005 5:26:40 PM PDT by Excuse_My_Bellicosity
6/8/2005 - LANGLEY AIR FORCE BASE, Va. (AFPN) -- A flight control system problem caused an F/A-22 Raptor to crash on the runway at Nellis Air Force Base, Nev., on Dec. 20, according to an Air Force report released June 8.
The pilot ejected and sustained minor injuries. The $133.3-million aircraft, assigned to the 422nd Test and Evaluation Squadron at Nellis, was destroyed when it crashed. Additional damage was limited to an arresting cable, runway guide sign, runway light and the runway itself.
The flight control system malfunction was caused by a brief power interruption to the aircrafts three rate sensor assemblies, which caused them to fail. The assemblies measure angular acceleration in all three axes: pitch, roll and yaw. With three failed assemblies, the F/A-22 is not able to fly, investigators said.
When the pilot shut down engines for maintenance servicing, he left the auxiliary power unit running. Based on technical order guidance, he believed the power unit would supply continuous power to the flight control system. However, there was a less-than-one second power interruption to the assemblies during engine shutdown.
There is no automatic warning of this condition. To discover it, the pilot would have had performed a diagnostic test. The pilot accomplished a successful test before engine shutdown, and because the power unit was on, he believed a second test was unnecessary. (Courtesy of Air Combat Command News Service)
No, it was caused by a lack of electricity. If a battery (or as another poster pointed out, a capacitor) had been wired into the system, there would not have been a power loss in the brief period of time between engine shutdown and apu takeover.
The problem might be solvable by either a manual or computer driven cut-over to the APU before the engine is shut down.
Sensor , Computer , its all part and parcel of the system.
The lack of electricity would have not been an issue if the pilot had known this. He would not have tried to take off until the gyros were fully up to speed, and no battery or capacitor would be needed.
But I am not representative of the average sw engineer. Sui generis.
I'm sure this mishap caused some tech order changes.
It's a good job it was caught during test and eval, and no one was hurt.
Yeah, and maybe one or two engineering vacancies.
Fly by light when it is about F/A-22...
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.