Tuesday, May 15, 2007

Omni Air DC-10 horizontal stabilizer malfunction

Omni Air InternationalThe National Transportation Safety Board (NTSB) has issued a preliminary report of a safety incident involving a DC-10 aircraft operated by Omni Air International, Inc. on May 2, 2007. According to the report, the aircraft "experienced a malfunction of the horizontal stabilizer during a normal descent" into Atlanta. The aircraft landed uneventfully at Atlanta's Hartsfield-Jackson International Airport, and there were no injuries to the 14 crew and 292 passengers.

Here is an excerpt from the NTSB report that describes what happened:
After takeoff the flight proceeded towards the destination airport and the captain later stated that while flying at 13,000 feet mean sea level (msl), and decelerating to 250 knots, the "Stab Out of Trim" light remained illuminated.

The autopilot was disengaged and the airplane suddenly pitched "aggressively" nose down, though the control yoke was guarded.

Attempts in resetting/moving the stabilizer setting using the pilot's and co-pilot's control yoke switches, alternate trim switches, and longitudinal trim handles were unsuccessful.

The approach was discontinued, and an emergency was declared with air traffic control (ATC). A "demanding amount of elevator back pressure was required to maintain level flight...", and the airplane was vectored for a landing on runway 27R, which was the runway requested.

The airplane was landed uneventfully on that runway with the flaps extended to 35 degrees, and the No. 2 engine at the flight idle position. The airplane taxied to the gate and the passengers were deplaned.

Preliminary examination of the airplane revealed that a shear pin/bolt in the horizontal stabilizer chain drive unit (P/N AJH7337-507) was fractured. The horizontal stabilizer chain drive unit was retained for further examination. [NTSB Report: MIA07IA088]
The passenger charter flight had originated in Shannon, Ireland.