Primary finding
Probable cause
The structural failure of the home-built landing platform during landing, which resulted in the helicopter rolling over.
Investigator assessment
Analysis narrative
The pilot reported that, during landing on a home-built landing platform, the helicopter landed normally and was stable. He reduced engine power and began to wait the prescribed engine cool-down period before shutdown. About 1 minute before the engine completely shut down, the platform collapsed, and the helicopter rolled aft and to the right and then came to rest on its right side. Postaccident examination of the platform revealed that it had a structural failure and had collapsed. The helicopter sustained substantial damage to the tailboom. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.
Source record
Factual narrative
The pilot reported that, during landing on a home-built landing platform (dolly), the helicopter landed normally and was stable. He reduced engine power and began to wait the prescribed engine cool down period before shutdown. About "60 seconds prior to complete shutdown", the platform (dolly) collapsed, and the helicopter rolled aft and to the right. The helicopter came to rest on its right side. Postaccident examination of the platform revealed that the home-built landing platform had a structural failure and collapsed. The helicopter sustained substantial damage to the tailboom. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.