On 21 February 2006, a Robinson Helicopter Company R44 'Astro' helicopter, registered VH-HBS, was being operated on a series of aerial survey flights approximately 100 km to the north of Mt Isa Airport, Qld. The helicopter was operating from Gunpowder airstrip and had completed three flights by 1254 Eastern Standard Time. The pilot refuelled the helicopter and at 1341 departed for a survey flight with three passengers on board. When the helicopter did not arrive at a pre-arranged rendezvous point, a search was initiated. Searchers found the burnt wreckage of the helicopter the next day. The four occupants were fatally injured.
The helicopter had impacted the ground with significant force in a nose-down, fuselage-level attitude. The main rotor displayed evidence of low rotational energy and coning. Other than impact and fire damage, there were no identified mechanical defects or abnormalities. There was evidence that the engine was rotating at impact, but the amount of engine power being developed was not able to be established.
The previous aerial survey flights were reported to have included low speed flight and occasional hovering. At the estimated helicopter weight and the prevailing air density, the helicopter did not have the performance to hover at the survey altitude, which was estimated to be about 1,000 ft above ground level. The investigation considered that the helicopter probably descended contrary to the pilot's intentions, possibly influenced by a partial engine power loss or downdraft, and induced the pilot to apply collective, which developed into overpitching and ultimately main rotor stall.
The investigation found that the helicopter was being operated at gross weights that exceeded the specified maximum take-off weight. The investigation also found that the operator's procedures did not provide a high level of assurance that a relatively low time pilot could conduct aerial survey operations safely.
Preliminary report released 10 April 2006
On 21 February 2006, at approximately 0630 Eastern Standard Time, a Robinson Helicopter Company Model R44 helicopter (R44), registered VH-HBS, departed Mt Isa, Qld, with two people on board. The helicopter was to position to the Gunpowder airstrip (approximately 100 km to the north) to meet a survey party.
Upon arrival at the airstrip, two other people boarded the helicopter and it departed to begin survey operations in the area between Mt Gordon Mine and Mt Kelly Mine, approximately 30 km to the south-west (Figure 1). During the morning, the helicopter returned to the airstrip at Gunpowder on three occasions to refuel and change personnel on board. It was reported that the helicopter was refuelled to full tanks on each occasion.
Figure 1: Survey area and accident location
It was reported that the helicopter refuelled for the last time at approximately 1300 and departed shortly after with four people on board to continue survey operations in the designated area. The helicopter was expected to rendezvous with the other members of the survey team at approximately 1530. When the helicopter failed to arrive, communication checks with the helicopter pilot and the helicopter operator were conducted and, when no contact with the helicopter was established, search and rescue procedures were initiated. The search continued into the night using a forward looking infrared (FLIR) equipped aircraft. The following morning additional helicopters and aircraft joined the search. At approximately 1100, the burnt wreckage of the helicopter was located on the top of a hill, situated on the edge of the survey area. Rescuers confirmed that all four persons on board had received fatal injuries.
Examination of the wreckage indicated that the helicopter had impacted the terrain heavily, approximately rotor-disc level and in a nose-down attitude. The helicopter came to rest on its right side (Figure 2). The main and tail rotor blades displayed evidence of low rotational energy at the point of impact. Further examination of the main rotor blades revealed compression wrinkling of the upper outer surface of both main rotor blades. All components of the helicopter were accounted for at the accident site.
Figure 2: Aerial view of helicopter wreckage
A severe, fuel-fed, post-impact fire destroyed the cabin and cockpit structure and surrounding flight and engine control systems. The fixed emergency locator transmitter (ELT) and the satellite telephone carried by the pilot were destroyed in the fire. No evidence of the portable ELT, reported to have been carried by the pilot, was found in the wreckage.
The area in which the helicopter was located was not considered to be suitable for a landing area for the R44 helicopter.
Weather conditions in the area were forecast to be fine with light easterly winds. Reported weather conditions in the area were consistent with that forecast.
The pilot held a commercial pilot (helicopter) licence and was appropriately endorsed to fly the R44 helicopter.
The ATSB has recovered the engine and a number of other components for further examination. One of the components recovered is an impact and fire damaged Global Positioning System (GPS) unit. A quantity of data has been successfully recovered from the GPS unit.
The investigation is continuing and will include:
- detailed examination of the engine and recovered components
- examination of the helicopter maintenance records
- further evaluation of the weather conditions
- a review of operational factors
- detailed examination of recovered GPS data.
|Date:||21 February 2006||Investigation status:||Completed|
|Location:||10km W Gunpowder, (ALA)|
|State:||Queensland||Occurrence type:||Collision with terrain|
|Release date:||02 October 2007||Occurrence class:||Operational|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||Fatal|
|Aircraft manufacturer||Robinson Helicopter Co|
|Type of operation||Aerial Work|
|Damage to aircraft||Destroyed|
|Departure point||Mt Isa, QLD|
|Departure time||0630 EST|
|Destination||Mt Isa, QLD|
|Role||Class of licence||Hours on type||Hours total|