What happened
On 12 April 2004, a student pilot was conducting a cross-country training flight in a Robinson R22 B2, registration EI-EHC. After departing Cork Airport, the pilot approached Shannon Airport from the south, requesting use of runway 31. While the forecast wind was light, the actual conditions at the time involved a 10-knot wind from 320 degrees.
During the approach, the pilot established an into-wind hover before proceeding to hover-taxi along taxiway D1. As the pilot moved along the taxiway, the aircraft began to feel unstable due to the crosswind component. To avoid a downwind turn, the pilot elected to land on the grass area east of the taxiway D1/light aircraft park intersection. The pilot described the touchdown as a hard landing, though they did not observe a high nose attitude at the moment of impact.
Following the landing, the pilot lifted the aircraft again to hover-taxi into the light aircraft park to shut down. A subsequent inspection of EI-EHC revealed a crease in the starboard side of the tail boom just behind the right-hand mounting bolts, along with a small scratch on the stinger.
The investigation
Investigators examined the aircraft and found that the tail rotor drive shaft was out of limits, necessitating its replacement. An engineer also noted that the undercarriage appeared slightly splayed, particularly on the rear left side. The tailcone assembly was sent to the manufacturer for necessary repairs.
Findings
- The structural damage to the tail boom was caused by compression buckling of the forward skin.
- This buckling resulted from compressive forces at the 4 o’clock position of the tailcone, created by the combination of vertical downward momentum from the tail rotor assembly and the lateral thrust of the tail rotor during touchdown.
- The pilot's decision to land on the grass to avoid a downwind track contributed to the impact dynamics.
- The investigation noted that the pilot could have potentially avoided the situation by making an earlier approach to the runway threshold to maintain an into-wind hover-taxi.