What happened
On the day of the incident, a Cessna aircraft, registration ZK-FTKS, departed Milford Sound carrying a full complement of passengers. The flight was intended to proceed to Queenstown; however, shortly after takeoff, the pilot noticed the engine was not operating as smoothly as usual. Consequently, the pilot decided to return to Milford Sound.
Upon returning to the aerodrome, the pilot consulted with engineering personnel and conducted ground running checks. Following these procedures, the pilot attempted a test circuit to verify the engine's performance. During this circuit, the engine's rough running persisted and eventually resulted in a total engine failure while the aircraft was on the late downwind leg. With the engine non-operational, the pilot was forced to seek an immediate landing site, eventually selecting a dry riverbed as the only viable option.
The investigation
The investigation focused on the mechanical state of the engine and the circumstances leading to the power loss. Investigators examined the damage sustained during the impact, noting that the nosewheel was torn from the aircraft. The landing took place on a surface strewn with boulders, which caused significant damage to the propeller, the engine structure, and the lower forward section of the airframe. There were no fatalities or injuries reported in the incident.
Findings
- The primary cause of the engine's irregular performance and subsequent shutdown was a defective fuel control unit.
- The pilot's decision to return to the base allowed for an assessment by ground crew, though the underlying mechanical fault remained active during the subsequent test flight.
- The terrain of the dry riverbed necessitated a high-impact landing, leading to structural damage to the aircraft.