An Air Midwest Beech 1900D twin turboprop pitched up to 52¼ before crashing out of control a few seconds after take-off from Charlotte Douglas Airport, South Carolina. National Transportation Safety Board (NTSB) member John Goglia says that an emergency call from the crew indicated "some sort of catastrophic event", and cited recent maintenance on the pitch control system as a subject that investigators would study quickly. Meanwhile, all 1900 operators are checking elevator control systems.
The aircraft was operating a scheduled US Airways Express service to Greenville-Spartanburg, South Carolina, fully laden with two pilots and 19 passengers - all of whom were killed. During its take-off shortly before 09.00 on 8 January the aircraft (N233YV) rotated normally at first, says Goglia, but then "something occurred to drive that pitch angle to 52¼". Manufacturer Raytheon Aircraft says normal rotate pitch is 7-10¼, rotation to 20-22¼ is "robust" and any angle above 30¼ is unsustainable. The 1900 reached 400-500ft (120-150m) above runway 18R, then veered left as it went out of control, one wing hitting a hangar.
"We do know that the elevator trim tab was replaced [on 6 January] and that would require cable tensions to be readjusted," says Goglia. "Those are significant events for the control system of this aircraft." The 1900 elevator system is cable controlled, and both elevators have trailing edge trim tabs that are also mechanically controlled by cables. They can either be adjusted manually or by an electric motor.
The flight data and cockpit voice recorders have been recovered, and indicate that the elevator occasionally moved erratically in the six flights since maintenance but had not shown such movement before.
The distribution of the aircraft's load - which affects the aircraft's centre of gravity - is also going to be checked in the early stages of the investigation, says Goglia.
Source: Flight International
