What happened
On June 12, 2001, a student pilot was conducting a solo navigation exercise in an R22 Beta helicopter, registration EI-CMI, departing from Birr Airfield. During the transition from a low-speed hover to a climb, the pilot perceived a significant loss of engine power and climbing performance. Fearing an imminent collision with nearby trees and utility poles, the pilot executed an emergency run-on landing in a field adjacent to the airfield.
As the aircraft decelerated during the final phase of the landing, it began to drift to the right. The pilot attempted to correct the drift with left rudder and reduced collective, but the helicopter ultimately rolled onto its right-hand side just before coming to a complete stop. The pilot evacuated the aircraft immediately and sustained no injuries, though the helicopter was damaged beyond economic repair.
The investigation
Investigators from the AAIU examined the aircraft and interviewed the pilot and local witnesses. Technical inspections of the engine and components revealed no mechanical malfunctions or defects that would account for a sudden loss of power. Eyewebitnesses at a nearby farmhouse reported hearing a grinding noise, describing the engine sound as being similar to a tractor, and noted the aircraft rocking from side to side.
Analysis of the flight parameters focused on the pilot's use of controls and environmental settings. The investigation looked into the pilot's flying experience, noting that his 54 total flight hours had been accumulated with significant, intermittent breaks in training. The investigation also examined the impact of the pilot's use of carburetor heat on engine performance.
Findings
- The pilot experienced a perceived loss of power due to a combination of continuous selection of full carburettor heat, over-pitching the collective, and initiating a climb at a speed lower than recommended.
- The use of full carburetor heat during the climb led to an approximate 10% reduction in available engine power.
- The pilot's recovery attempts—reducing collective and pitching forward—actually hindered the recovery of engine and rotor RPM.
- Directional control was lost during the deceleration phase of the emergency landing, leading to the rollover.
- The pilot's lack of recent flying currency contributed to the difficulty in managing the deteriorating flight conditions.
Safety action
Following the investigation, a safety recommendation was made to the Robinson Helicopter Company to include a warning in the Pilot’s Operating Manual. This warning should note that applying excessive carburetor heat during high power settings or take-off can adversely affect engine power and overall helicopter performance.