Background
The day before the accident, the pilot noted that the normal brakes were inoperative. Maintenance was notified, and personnel advised the brakes would be inspected during a planned 25-hour inspection that evening. The next morning, the pilot learned the brakes had not been repaired. While in dispatch for a search and rescue mission located approximately 40 miles from the helibase, the pilot expressed concern to the chief pilot about operating the helicopter with inoperative brakes. The chief pilot felt it was acceptable for the flight to proceed, noting the urgency of the search and rescue mission and considering the brake deficiency minor. The chief pilot and the director of maintenance were aware of the issue; the helicopter was not taken out of service.
Flight and Landing
The flight departed and proceeded to the search area with negative results, then returned to the helibase. After arrival, the pilot performed a hover power check. Subsequently, the pilot maneuvered the helicopter over the landing pad. The chief pilot was standing by with chocks to chock the wheels upon landing, as previously arranged due to the inoperative brakes. The pilot made a normal touchdown, and as the nose gear lowered, he expected the chief pilot to chock the wheels.
Sequence of Events
As the helicopter settled, it rolled forward toward the hangar. The pilot attempted to control the forward movement using flight controls, aware of cyclic limitations during ground operations, but could not arrest the movement. The chocks were not in place. The pilot then felt the helicopter vibrating, followed by extreme cyclic movements in the cockpit. The pilot stated the helicopter encountered what he felt were normal vibrations and was not certain the helicopter experienced complete ground resonance. He attempted to lift to a hover to correct the situation but was not sure if the helicopter became airborne.
The passenger noticed the helicopter rolling forward after landing, heard the pilot say the helicopter was lifting, and felt a vibration that turned into violent shaking. The helicopter moved over grass and began moving faster. The passenger observed parts separating from the helicopter either when it stopped moving toward the ground or the nose landing gear fully compressed. An object struck the passenger's left arm and thigh, coming to rest on the floor near his feet. The pilot attempted to secure the engine, and the passenger smelled jet fuel before evacuating the wreckage.
The chief pilot reported the pilot made a normal approach with a power check at low hover, then maneuvered to land. After touchdown, the helicopter began to roll forward slightly. The pilot attempted to lift to a hover; when only the main landing gears were on the ground but fully extended, the helicopter began shaking. The chief pilot heard a loud crash, and both occupants exited. He secured the engine using the emergency fuel shutoff lever.
Aftermath
Review of the "Aircraft Contract Daily Diary" for the day before the accident recorded, "Hydraulic brakes not working-mechanic notified." According to a FAA airworthiness inspector, maintenance personnel from the helicopter's owner performed maintenance on the wheel brakes the day before but lacked a proper fitting to bleed them. They were scheduled to bleed the brakes on the accident day but did not. No maintenance record entry was made indicating the brakes were inoperative. The helicopter did not have an FAA-approved minimum equipment list (MEL).