The importance of flight crew and maintenance engineer communication
It was during a standard takeoff and shortly after rotation when the #2 engine of a Beech 200 inadvertently lost power. To make matters worse during this critical phase of flight, the failing engines propeller did not auto-feather, further impairing the aeroplanes ability to climb.
The flight crew manually selected the failed engine into feather, continued their climb to an adequate altitude and returned safely back to the airport.
Upon investigating the #2 engine power loss, it was noted that the friction knob was loose and in this position with both throttle levers set to full power and released, the right throttle lever would inadvertently move back to flight idle but the left throttle lever would remain in the full power position.
As a standard procedure and during a normal take-off, the captain’s right hand would have been on the throttle levers with the first officer’s left hand firmly behind it. After take-off the captain would promptly return his right hand back on to the control wheel and the co-pilot’s left hand would have moved to select gear up.
As confirmed by the flight crew, this is when the aeroplane experienced the #2 engine power loss. Therefore it was suspected that with the throttle lever friction knob set in a loose position, the right throttle lever could have moved back towards the flight idle position, causing the #2 engine to lose take-off power. Also with the right throttle lever back in its flight idle position, the auto-feather switches would not have been made, disabling the auto feather function for that engine.
The right throttle lever cable assembly was replaced and as a precautionary action, this included the high-pressure fuel pump, the main engine fuel control unit and flow divider. The complete fuel system was inspected for any possible blockage and a full functional test was performed to confirm for correct throttle power lever system control. Engine runs were carried out with the auto-feather system testing serviceable and a test flight was completed.
All shop teardown reports for the fuel pump, control unit and flow divider came back as serviceable with no significant faults found, confirming the suspected throttle cable failure.
Through the maintenance engineer’s determination to investigate and communicate with the flight crew, the root cause failure of the throttle cable was confirmed, with all other possible scenarios addressed.
A job well done by all involved in promoting a high level of aviation safety.
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