TEAM AIRBIKE N7566D accident near Ocean Springs, Mississippi

Probable cause

An intermittent failure of the power take-off cylinder ignition coil, which resulted in a partial loss of engine power.

NTSB analysis

During a prebuy inspection flight, the airline transport pilot reduced engine power to test the airplane's slow-speed handling characteristics. He then increased the throttle to restore full engine power, but the engine seemed to "bog down" and lose power. He then lowered the airplane's nose, and engine power was restored. The pilot then chose to return to the airport, and while on approach, the engine again began to lose power, but lowering the airplane's nose did not increase the rpm this time. The pilot realized the airplane would be unable to reach the airport, so he conducted an off-airport landing in a residential area, during which the airplane impacted a fence.

A postaccident engine run revealed that, after running at various power settings, when the power was reduced, the engine bogged down and backfired through the power takeoff (PTO) carburetor, and the rpm would not increase. The PTO cylinder ignition coil was replaced with a serviceable coil, and the engine was restarted for several minutes and run through various power setting. The engine accelerated normally without backfiring, hesitating, or stumbling.

It is likely that, during the accident flight, the PTO cylinder ignition coil broke down, which resulted in an intermittent spark at the PTO spark plug and a partial loss of engine power.

Text from the NTSB. Open the NTSB docket for ANC18LA002 for the full record.