What happened
On the morning of 24 April 2005, two separate training operations were underway at Sherburn-in-Elmet, Leeds. Earlier in the day, an instructor had parked a Robinson R22 Beta, G-CDBG, at the airfield's refuelling area. Shortly thereafter, another instructor parked a Robinson R244 Astro, G-OLOW, in a position adjacent to the R22.
For the second flight, an instructor returned to the Robinson R44 Astro with a student pilot. While the instructor went to retrieve a missing checklist, the student performed the external pre-flight inspection. As part of this procedure, the student rotated the main rotor blades 180 degrees to check for sufficient clearance from the stationary Robinson R22 Beta.
Once the instructor returned, the Robinson R44 Astro was started. During the start-up sequence, the rotating blades of the Robinson R44 Astro made contact with the blades of the already running Robinson R22 Beta. The impact caused a sudden bang and intense vertical vibration in the R22, leading the instructor to shut down the aircraft. Both aircraft sustained damage to their main rotor blades and experienced engine shock loading. There were no injuries to the two crew members on board each aircraft.
The investigation
The investigation was based on accident report forms provided by the pilots. The inquiry established that the instructor of the Robinson R44 Astro had operated under the incorrect assumption that the pilot who originally parked the aircraft had left enough space between the two helicopters to avoid contact.
Findings
- The collision occurred because the main rotor blades of the Robinson R44 Astro struck the blades of the running Robinson R22 Beta.
- Inadequate clearance between the parked aircraft was the primary factor leading to the contact.
- The instructor of the Robinson R44 Astro incorrectly assumed that sufficient separation had been maintained by the previous pilot.