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Analysis

Summary

The aircraft took off with the fuel caps for the left wing tanks not secured, and the flap covers unlocked. It could not be established if the flap covers remained in the opened (up) position where they were left by the refueller, or whether they moved to the closed/not locked position because of aircraft movement or vibration, or airflow.

There may have been some perceived time pressure regarding the pre-flight inspection because of the deteriorating light. Further, the light may have reduced the visual prominence of the open flap covers. Either, or both of those influences could have contributed to the pilots not being aware that the left wing fuel caps were not secured.

As the aircraft accelerated during the takeoff roll, the caps fell from the left wing filler ports, probably as a result of vibration and/or aerodynamic forces. The 'smoke' observed by the tower controller and a witness was fuel venting from the open tank filler ports. It was unlikely that any other interpretation of the venting fuel would reasonably have been made in the circumstances, particularly in the deteriorating ambient light conditions, coupled with the position of the filler ports on either side of the engine nacelle.

Other than the tower controller's transmission regarding the 'smoke', it could not be determined what other information the pilots of the aircraft used in reaching the decisions to shut down the left engine and attempt a left turnback. However, based on the examination of the left engine and propeller, there would most probably have been no indication from the cockpit instruments that the left engine was malfunctioning in any way. Whether the pilots were able to observe the 'smoke', or became aware of the situation regarding the fuel caps, could not be determined.

It was apparent from the record of communications with the control tower that the pilot who initiated communications with the air traffic controller prior to take off was not the same person who communicated with the tower controller following the advice that there was 'smoke' coming from the left engine. However, which pilot manipulated the aircraft controls during that period could not be determined.

At the time the aircraft passed abeam the control tower, there was adequate runway and overrun distance available for the aircraft to land and decelerate significantly before reaching the boundary fence. Whether the pilots considered the option of landing straight ahead after being notified of the 'smoke' could not be determined.

The flight path taken by the aircraft (the turn away from the live engine) and the aircraft configuration at impact (left propeller not feathered, landing gear extended) indicated that aspects critical to maintaining single engine performance were not accomplished. The final flight path and impact attitude of the aircraft were typical of what might be expected following loss of control when the airspeed falls below the minimum single engine control speed.

 
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