What happened
The incident occurred when a passenger arrived for a scheduled charter flight, but the originally intended aircraft failed to start. As a result, a Cessna A185F with tail number N3343S, equipped with both wheels and skis, was selected to conduct the flight. The pilot reported that temperatures had been extremely cold during the preceding night. Prior to the flight, he preheated the engine and performed a run-up, after which he replaced the engine cover and plugged in an external heater.
While taxiing to the runway, the pilot cycled the propeller once. However, he noted that the oil temperature had not yet reached the operating range. At an ambient temperature of -21 degrees Fahrenheit, the oil did not warm up sufficiently at the low power settings required for taxiing. The takeoff proceeded normally until the pilot reduced the propeller RPM. Shortly thereafter, the engine surged.
The pilot attributed the surge to cold oil in the governor system and decided to return to the airport for landing. During the turn back, he reportedly diverted his attention from the flight path. The aircraft stalled while attempting recovery and struck the ground.
The investigation
Examination of the event revealed that the engine surge was directly linked to the operational conditions of the lubrication system in extreme cold. The pilot's decision to taxi with insufficient oil temperature contributed to the governor malfunction. Additionally, the loss of control during the return flight was exacerbated by a lapse in situational awareness during the critical phase of the maneuver.
Findings
Contributing factors included:
- Extremely low ambient temperatures affecting engine oil viscosity and heating time
- Inadequate warm-up of the oil system prior to takeoff
- Engine surge due to cold oil in the governor system
- Pilot distraction during the return turn
- Stall during recovery from the turn
The combination of mechanical limitation due to cold weather and human factors led to the accident.