Bell 206 N523RL incident near Gulf Of Mexico, Louisiana

Probable cause

Improper reassembly of the collective flight controls by maintenance personnel. Contributing to the incident were inadequate postmaintenance examinations by maintenance personnel and inadequate preflight inspections by two pilots.

NTSB analysis

According to the pilot, the helicopter was on final approach to a platform in the Gulf of Mexico when he raised the collective to perform a go-around. However, the helicopter did not respond properly; rather, its performance and torque indications remained fixed at 45 percent. The pilot began a slow climb and diverted to a land-based airport at a cruise speed of about 60 knots. Because of a complete loss of collective pitch control, the pilot made a running landing on the runway at the airport, touching down about 45 knots. The helicopter came to a stop in the grass about 100 feet past the end of the runway. An examination of the helicopter revealed that several fasteners were missing from the top clevis of the collective control tube, which led to the control tube becoming disconnected from the collective pitch arm on the swash plate. The missing fasteners were found loose on the deck in the transmission compartment. Records showed that maintenance to reinstall the transmission and main rotor hub had been completed about 6 flight hours before the incident and that several mechanics and two pilots had examined the helicopter before the incident flight without noting the improperly secured/missing fasteners.

Text from the NTSB. Open the NTSB docket for CEN10IA397 for the full record.