Amateur-built BD5 N501BD accident near Camarillo, California

Probable cause

The No. 4 connecting rod’s bearing shift and separation of the No. 4 connecting rod, which resulted in a total loss of engine power and subsequent forced landing.

NTSB analysis

The pilot departed in the experimental, amateur-built airplane and remained in the airport traffic pattern. The tower controller noticed that the airplane was low on the downwind leg and asked the pilot if he could climb. The pilot responded that he was having issues climbing and would need to stay at that altitude. The pilot also stated that he would need to make a full-stop landing. The pilot was cleared to land, and, shortly thereafter, the airplane was observed in a rapid descent.

Several witnesses located near the accident site reported that the airplane was low before it descended rapidly toward the ground. One witness stated that the propeller was not moving. The airplane impacted a lettuce field about 3/4 mile south of the airport and immediately nosed over.

Postaccident examination of the engine revealed that the connecting rod bearing, and endcap had separated from the crankshaft. Engine disassembly revealed that the engine’s oil galleys and the No. 4 connecting rod journal’s oil galley were not obstructed. The section of the rod end cap with the bearing tang insert had mechanical damage consistent with bearing shift. The bearing shift likely led to the No. 4 rod bearing and endcaps to separate and resulted in a total loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR20FA005 for the full record.