Control system problem blamed in Raptor crash

Jeff Donaldson

Thursday, June 9, 2005 | 8:25 a.m.

A flight control system problem caused the Dec. 20 crash of an F/A-22 Raptor on the runway at Nellis Air Force Base, the Air Force said in a report released Wednesday.

The pilot ejected and sustained only minor injuries in the accident.

The $133.3 million Raptor was one of eight of the Air Force's new stealthy fighters currently being tested at Nellis as part of the 422nd Test and Evaluation Squadron.

Despite the accident the F/A-22 program moved into its final phase of testing in February.

The seven remaining fighters will undergo more than 80 missions that will help pilots essentially write the textbook for how to use the Raptor in combat. The fighter is expected to be deployed for its first operational missions in December as part of a Raptor squadron assigned to Langley Air Force Base, Va.

"With all development combat aircraft programs, it's important when an accident happens to determine what caused it and prevent it from happening again," said Capt. Steve Rolenc, spokesman for the Air Warfare Center at Nellis.

The December accident occurred almost immediately after the aircraft took off at 3:40 p.m. on Dec. 20. Immediately upon leaving the ground, the Raptor began a series of uncommanded and violent rolling and turning maneuvers -- known by pilots as pitch, roll and yaw.

Unable to get control of the aircraft, the pilot ejected just seconds before the jet hit the ground. The aircraft was destroyed, with debris causing damage to the runway, an arresting cable, runway lights and runway signs.

According to the accident investigation, the flight control system malfunction likely occurred because of a brief power failure in the sensors that monitor the aircraft's maneuvers.

Known as RSAs, or rate sensor assemblies, the monitors were affected by a split-second power interruption during engine shutdown.

Based on technical orders used at that time by pilots flying the F/A-22, the aircraft's backup power systems could remain running while pilots shut down the engines. Rolenc said all program personnel working with the Raptors have since been advised to shut the systems down.

"(The Air Force) has rewritten the technical order, and we're retrofitting the F/A-22s with a new model of RSAs that will prevent this from happening again," Rolenc said. "That's important for the program."

The 422nd is expected to complete writing the Raptor's tactics book in October. By 2008, a squadron of 17 Raptors is expected to be assigned to Nellis so that the base's weapons school can begin operating the equivalent of a doctorate-level instructor training for the aircraft.

Eventually, a total of 28 Raptors will be in use by the Air Force, taking the place of aging F-15 fighters.