What happened
On September 4, 2012, an Agusta Bell 206-3B helicopter, registration A6-FTB, was conducting a training flight in the Al Ain Training Area Six. The flight, operated by Horizon International Flight Academy, involved an instructor and a student pilot performing engine-out landing (EOL) autorotation exercises.
After successfully completing the first 360-degree autorotation, the crew began the second exercise. During this maneuver, the aircraft entered an unstable state while close to the ground. Although the instructor attempted to take control to stabilize the flight attitude and arrest the descent, the helicopter struck the ground with a high rate of descent and very little forward speed. The impact caused the primary structure to deform significantly, led to a rotor strike on the rear of the tail boom, and caused the transmission and rotor assembly to separate from the airframe.
The investigation
Investigators from the GCAA AAIS examined the wreckage and the flight sequence. The investigation included a technical evaluation of the Rolls Royce M250 engine. The engine was sent to Rolls-Royce for testing, where it was subjected to various power calibration checks and acceleration/deceleration tests. The testing confirmed that the engine met specifications for takeoff and most cruise settings, though it showed slightly low performance at specific cruise power points. No mechanical defects were found during the engine testing that would have prevented normal operation.
Findings
- The primary cause of the accident was a loss of control during the second autorotation exercise.
- The aircraft impacted the terrain with a high vertical descent rate and minimal forward velocity.
- The impact resulted in the separation of major structural components, including the rotor assembly.
- Both crew members survived the accident without any injuries.