What happened
On the afternoon of 2 February 2003, a Cessna U206G, registration ZK-EJG, departed from runway 21 at Ardmore Aerodrome as part of a routine charter flight. The aircraft, operated by Waiheke Air Service Limited, was performing a series of trips between Waiheke Island and Great Barrier Island.
After taking off with full power, the pilot began a left turn at approximately 600 feet. During this maneuver, the engine suddenly lost all power following a loud mechanical noise. The pilot observed oil spraying onto the windscreen and the propeller immediately ceased rotation. Demonstrating effective emergency procedures, the pilot transitioned the aircraft into a glide and initiated a return to the airfield. The aircraft successfully landed on the reciprocal runway, runway 03, halfway down its length. There were no injuries to the pilot or the two passengers on board, and the aircraft sustained only minor damage to the cowling.
The investigation
Investigators examined the Teledyne Continental IO-520-F engine to determine the cause of the sudden stoppage. The inspection revealed that the engine crankcase had been punctured by internal components. Specifically, the caps for the number 1 and number 2 connecting rods had separated, and a portion of a broken connecting rod was protruding through the engine casing.
Technical analysis showed that the retaining bolts for these rods had failed due to gross overload. While the exact origin of the failure—whether due to material defect, contamination, or improper handling—could not be definitively identified, the condition of the bearings suggested a period of progressive degradation. The investigation noted that the damage to the bearings was consistent with wear occurring over several hundred engine hours.
Findings
- The engine failure was caused by the separation of the connecting rod caps on the number 1 and number 2 cylinders.
- The pilot's immediate and appropriate response to the engine failure prevented injuries and further damage to the aircraft.
- The mechanical failure may have been preceded by a long-term degradation of the bearings.
- Regular technical analysis of engine waste oil might have detected the progressive deterioration of the components before the catastrophic failure occurred.