What happened
On March 18, 2002, a Hughes 269C helicopter, registration ZS-HVD, was conducting a private flight departing from Farm Doornlaagte near Deben in the Northern Cape. Shortly after the aircraft became airborne, the engine experienced a loss of power, which quickly escalated into a complete engine failure during flight.
In response to the loss of power, the pilot attempted to locate a suitable area for an emergency landing. During this maneuver, the main rotor RPM decreased significantly. The pilot subsequently performed a forced landing into a densely wooded area. The impact of the hard landing caused the rear cross tube assembly to fail, which resulted in the main rotor blades severing the tail boom.
The investigation
The investigation focused on the mechanical failure of the engine and the structural damage sustained during the landing. Investigators examined the engine components to determine why power was lost during the initial climb. The inquiry also assessed the flight dynamics and the impact of the rotor RPM decay on the aircraft's stability during the forced landing.
Findings
- The primary cause of the engine failure was the seizure of the No. 3 connecting rod big-end bearing.
- This seizure was triggered by a period of restricted oil flow to the big-end bearing.
- The pilot's attempt to select a landing site led to a substantial decay in main rotor RPM.
- The structural failure of the tail boom was a direct result of the rear cross tube assembly failing upon the hard impact with the ground.