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Monday, March 8, 2004

Poor Maintenance Cited As Primary Cause Of Air Midwest Crash

In the chain of events leading to the fatal Jan. 8, 2003, crash of an Air Midwest Beech 1900D twin-turboprop, the pilots' inability to prevent the nose from pitching up excessively into a stall was the end result of improper maintenance performed on the airplane's elevator two days before.

However, even with the mis-rigged elevator, the pilots might have been able to recover the situation had not the payload been distributed toward the tail, such that the airplane was a good 5 percent out of its aft center of gravity limit (CRAN, June 2, 2003).

The Beech 1900D was some 600 pounds overweight for takeoff, but National Transportation Safety Board (NTSB) investigators determined that being out of the aft center of gravity limit was a more critical factor. If the airplane had simply been overloaded, the crew could have handled the plane even with the elevator problem.

Poor maintenance came under intense scrutiny at the NTSB's final hearing Feb. 26. If the maintenance manual, since revised extensively, had been available for the elevator control cable rigging work done on the airplane during maintenance two days before, the cables more likely would have been rigged properly. For want of a good manual, the work was done wrong. For want of properly rigged elevator cables, the airplane and all 21 passengers and crew aboard were lost.

"After an accident like that, you reassess," said Jonathan Ornstein, chief executive of Air Midwest's parent company, Mesa Air Group [MESA]. The carrier is in the process of pulling all its routine maintenance back in-house. "In the past, it was not a financial issue. We went to Raytheon Aerospace because it was almost like bringing your car to a dealership. We thought we were getting a high quality product. It was [the] best maintenance money could buy."

(Raytheon Aerospace, since renamed Vertex, is not related to aircraft manufacturer Raytheon Aircraft Corp., manufacturer of the Beech 1900D).

On the night of Jan. 6, 2003, the elevator control system underwent a cable tension check. The NTSB found that the five contract mechanics who performed the work at Huntington, W.Va., on the accident airplane had virtually "zero experience" on the Beech 1900.

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