What happened
On 15 November 2009, a Robinson R22 Beta, registration G-RIDL, was performing a private local flight near Macclesfield, Cheshire. The pilot, who was also the aircraft owner, had departed from a site near Manchester Airport with the intention of returning after approximately one hour.
During the flight, witnesses observed the helicopter flying at an altitude between 500 and 1,000 feet. One observer noted the aircraft rocking from side to side and heard a loud noise described as a "bang" or "clatter," while the engine appeared to be running. The helicopter then began a descent. The aircraft struck the ground in a tail-down attitude, causing the tail rotor blades to fail and the fuselage to rotate. The pilot sustained fatal injuries.
The investigation
The AAIB examined the wreckage and recovered GPS data, though the device's battery was insufficient to provide a full flight track. Investigators analyzed the engine and ignition system, specifically focusing on the two magnetos. While the engine was capable of producing its rated power, testing revealed an intermittent misfire in the number four cylinder.
Detailed inspection of the left magneto revealed evidence of water ingress. This moisture led to the formation of oxide layers on electrical contacts and caused a depression in the magneto coil tab. Such defects can cause arcing and delayed spark generation, leading to engine vibration. The investigation also looked into the pilot's recent flying history and medical status, noting that the pilot had been using undeclared medication that could impact physiological performance.
Findings
- The left magneto showed signs of deterioration due to moisture-induced oxidation, which likely caused the engine vibration and noise that prompted the pilot to attempt a landing.
- The pilot may have incorrectly attributed the engine's mechanical symptoms to a known, pre-existing issue with the rotor clutch warning light.
- The tail rotor blades failed due to the impact of the tail striking the ground during the landing sequence.
- The pilot's recent lack of flying experience and the potential physiological effects of undeclared medication may have affected aircraft handling during the critical stages of the landing.