Accident Sequence
The helicopter was observed by witnesses flying at a low altitude and low airspeed. Witnesses then heard the engine sputter before the helicopter lost control and landed hard in a residential area.
Engine Examination
Examination of the engine revealed evidence that two exhaust valves had stuck open due to contamination by products of combustion. The engine manufacturer publishes maintenance procedures to prevent such an occurrence, which could result in a partial loss of power. The helicopter operator elected not to perform the recommended procedure.
Shoulder Harness Findings
The pilot's shoulder harness failed during the accident, whereas the passenger's shoulder harness did not. The failure occurred in a worn area where the harness bends over the seat back. Both shoulder harnesses were not marked with the required data; the cloth data tags were missing. The history or manufacturer of the shoulder harnesses was not determined.
Maintenance History
The helicopter had undergone an annual inspection about six months before the accident. Since that annual, both a 100-hour and a 50-hour inspection had been accomplished. These inspections failed to detect the discrepancies with the shoulder harnesses.
Toxicology Results
Toxicological testing revealed the presence in the blood of desalkylflurazepam, an active metabolite of flurazepam (Dalmane), commonly used to treat insomnia. Additionally, the urine contained pseudoephedrine, phenylpropanolamine, ephedrine, and salicylate, substances commonly found in over-the-counter cold medications.