Canberra Times
Helicopter pilot cleared of crash error
17 December 2003
Despite pushing as hard as he could on the left rudder pedal of his Bell 206 JetRanger helicopter, pilot Duncan Patrick could not have averted the crash at Bendora Dam which nearly claimed his life on January 13.
An exhaustive 11-month inquiry by the Australian Transport Safety Bureau has absolved Mr Patrick of blame in the accident, which occurred as he was conducting aerial water-bombing over the Namadji National Park, southwest of Canberra.
The bureau's findings were issued yesterday, and while investigators could not provide a definite cause for the crash, a series of factors was seen as possibly contributing to it.
It was found that the straps holding the 455-litre fire-fighting bucket were not standard, and the strap had been tied with a knot, which is not recommended.
Webbing loops which control the volume of water scooped up by the device had been torn loose from the wall of the bucket. This may have let more water into the bucket and increased its weight.
Investigators were also puzzled to find that the automatic circuit breaker, which trips in an emergency to release the cargo hook, was in the "open" position.
This means that either as a result of pilot selection or the accident, the 420kg load could not be automatically released when the emergency occurred.
Tests revealed later that the circuit breaker was operating normally.
Although the helicopter was seen as operating within its safety limits on the day of the crash, there was little margin for error.
The "maximum take-off all-up weight" for a JetRanger under those ambient conditions was 1505kg. The safety bureau has estimated that when the helicopter crashed, its all-up weight, including 420kg of water in its bucket, was 1500kg.
Visibility was reported as "good" with some smoke in the area, and a Department of Meteorology report indicated a wind speed of 15 knots.
Mr Patrick, a pilot highly experienced in aerial fire-fighting and long-line operations, suffered traumatic head injuries in the crash. He has no memory of what happened but investigators are certain his life was saved by his safety helmet, and the timely arrival of a trained air-sea rescue crewman who hauled him from the submerged wreckage.
His helmet was badly damaged either as a result of hitting the helicopter door frame, or from being bashed by the main rotor blade.
The bureau believes the JetRanger, operating in high temperatures which rob the engines of optimum power and the main rotor blades of maximum lift, experienced what is known as a loss of tail-rotor effectiveness.
"All of the conditions of the day may have conspired against the operation," bureau deputy director Alan Stray said. "With 420 litres of water in the bucket, the high power needed for the lift, and the low forward speed, increasing amounts of left tail rotor input are required."
The loss of control occurred so quickly that Mr Stray believes the experienced pilot would have had seconds to comprehend the seriousness of the situation before the helicopter slewed sideways and plunged into the dam.
By fortunate coincidence, the Snowy Hydro SouthCare helicopter swooped on the crash site, crewman Euan McKenzie leapt from the open cabin door and dived into the dam. The officer swam down, dragged Mr Patrick's unconscious body from the submerged wreckage.
Mr Patrick was resuscitated and after a three-week recovery in Canberra Hospital returned to Queensland for further rest and rehabilitation. He has not flown since the accident.