Some US Marine Corps and US Air Force Bell Boeing V-22 Osprey tilt-rotors were returned to flight last week after being grounded when a flight-control computer fault was found during factory testing.
While a fix is developed, flight-control computers with an earlier microchip have been pooled and installed in 16 USMC MV-22s and three USAF CV-22s to allowing testing and training to continue.
The fault in a chip that ensures redundancy in the V-22’s triplex digital fly-by-wire system, by detecting and isolating a failed flight-control computer, was discovered during start-up testing of a V-22 on Bell’s Amarillo, Texas assembly line. Analysis found the Texas Instruments chip reacts poorly in cold temperatures.
The commercial chip has been used by flight-control computer supplier BAE Systems since 2003, and was believed to be functionally identical to the chip previously used, which came from a different manufacturer. “We are still looking into how a chip that was not suitable for this application came to be incorporated,” says the Navy.
Thirty-five Ospreys - 30 MV-22s and five CV-22s – remain grounded until a “minor modification” to the flight-control computer is qualified. “We will leave the chip on the [circuit] board and make minor changes to the board,” says the navy. Flight tests were planned for late last week, with flight clearance expected by the end of February.
n US Air Force Lockheed Martin F-22A Raptors were scheduled to fly from Hawaii to Japan last weekend after a software fix to cure a navigation system anomaly that forced the aircraft to abandon their 11 February first attempt to cross the Pacific. The 12 F-22s were en route to Kadena AB on Okinawa for the Raptor’s first overseas deployment when the problem forced them to turn back to Hickam AFB in Hawaii.
For exclusive news and expert analysis every week subscribe to Flight International print edition. Included with your subscription are 4 FREE issues and FREE delivery to your home or office.
Full tilt ahead: What will follow the V-22?
(07/11/06)
Boeing searches for cheaper Osprey tiltrotor
(03/10/06)