On 1 September 2005, the crew of an Embraer EMB110-P2 (Bandeirante)
aircraft, registered VH-OZF, was conducting a private flight under the visual
flight rules from Bankstown Airport to Camden, NSW. At 1343 Eastern Standard
Time, on the initial climb from runway 11 Left (11L), the pilot in command
(PIC) experienced excessive nose down pitch control forces.
The PIC attempted
to correct the pitch force with the manual elevator trim wheel and electric
trim, but the trim did not move. The copilot assisted by applying back pressure
to his control column and observed that the elevator trim wheel was in the
full nose down position. The pilots were unable to maintain altitude and the
aircraft descended from approximately 470 to 150 ft.
The PIC reduced engine
power and the airspeed reduced. The copilot applied significant force to the
elevator trim wheel and the wheel released from the full nose down position.
The pilots regained control and landed.
The investigation found that the left
yoke-mounted trim switch did not to return to the neutral position, when operated
and released, due to a sticky substance binding the levers. It also found that
the elevator electric trim servo mechanical clutch did not release at the specified
setting due to a lack of maintenance.
The circumstances of this event were consistent with an electric trim runaway
occurring during or shortly after take-off. The investigation established that
the trim runaway was probably due to the non return of the switch from the
nose down position or an unidentified electrical fault.
The pilots reported
that they were unable to pull the electric trim circuit breaker, in accordance
with the manufacturer’s procedure, because they
were unable to release the control column.
As a result of the investigation
the operator and manufacturer initiated a number of safety actions.
