Loss of control

On 13 May 2011, at 1606 Eastern Standard Time, an Aérospatiale Eurocopter AS 350B3 helicopter, registered VH-XXW, impacted terrain at Bankstown Airport, New South Wales. As the result of the post-impact fire, the helicopter sustained serious damage.

The owner-pilot had earlier completed an 'air transit' at about 15-20 ft above ground level (AGL), from outside a hangar, to a grassed area south-west of the main helipad.

While stationary in a hover, with a recorded 15 kt wind onto the right front of the helicopter, and at about 10 ft AGL, the pilot decided to land on the grass. When the helicopter was about 2 ft AGL, the pilot stated that it suddenly rotated to the left in an anticlockwise direction. The pilot was unable to correct the anticlockwise yaw with progressive right pedal input. The pilot then raised the collective lever and climbed to about 10 ft AGL, completing about three to four, 360 º rotations.

At the same time, the pilot noticed the helicopter drifting towards a chain-wire fence adjacent to a freight building. During the uncontrolled anticlockwise yaw, the pilot reported that there were no visual or aural warnings. While still rotating, the pilot decided to conduct a forced landing and slowly lowered the collective lever. The helicopter contacted the ground, rolled onto its right side and was seriously damaged from the post-impact fuel fed fire. The pilot sustained minor injuries.

Preliminary report released 18 March 2011

On 4 February 2011, a Robinson Helicopter Company R44 Astro helicopter (R44), registered VH‑HFH, was conducting circuit operations at Cessnock Aerodrome, New South Wales. On board the helicopter were an instructor, a pilot undergoing a helicopter flight review and a passenger.

Following the completion of a sequence involving the simulated failure of the helicopter's hydraulic‑boost system, the instructor assessed that the hydraulic system had actually failed. He elected to reposition the helicopter on the aerodrome to facilitate further examination. Upon becoming airborne, control of the helicopter was lost, and it collided with the runway and, shortly after, there was a fire. The pilot managed to exit the helicopter; however, the instructor and passenger were fatally injured.

Examination of the wreckage identified that a bolt securing part of the flight control system had detached. Although the circumstances of the accident are still under investigation, the Australian Transport Safety Bureau has, in the interest of transport safety, issued a Safety Advisory Notice suggesting that operators of hydraulic system-equipped R44 helicopters, and organisations performing inspection, testing, maintenance and repair activities on the flight controls of those helicopters, inspect and confirm the security of the aircraft's hydraulic-boost servos.

After a number of dual circuits, the pilot was authorized to carry out solo circuits with touch and go landings. After the first touchdown the pilot applied full power then selected the flap to 10 degrees. The aircraft entered a rapid turn to the left, and the pilot abandoned the take-off. The aircraft slid sideways off the strip and the nosewheel was broken off. The pilot was carrying out her first solo period of touch and go landings. After applying full power she noticed that the aircraft was accelerating more quickly than when she had been under dual instruction. The pilot had previously required forward pressure on the control column while retrimming the aircraft. On this occasion she had not had time to retrim and the investigation revealed that the aircraft had been "wheelbarrowing" on the nosewheel when directional control was lost.

The pilot had hired the aircraft in order to maintain currency on the type. After an uneventful flight in the training area he returned to the circuit and carried out a normal approach. However, shortly after touchdown the aircraft swerved to the left and the pilot was unable to regain directional control. The aircraft ran off the side of the runway and the nosegear collapsed. It was discovered that the elevator trim had been set almost fully nose down, and the rudder trim was set almost fully nose left at the time of the accident. The nosewheel had contacted the runway at about the same time as the mainwheels, and it was likely that the subsequent loss of control was the result of the aircraft "wheel-barrowing" on the nosewheel. The pilot, who had only limited experience on the type, had believed that the aircraft had been correctly trimmed prior to touchdown.

The pilot, who was also the holder of a Private Pilot Licence, was conducting his first gliding flight for the day. The glider was aero-towed to 1100 feet above the aerodrome, but only weak lift was encountered in the area. The pilot elected to return for landing and commenced a normal circuit. On the downwind leg strong sink was encountered and the base turn was conducted at about 300 feet above the ground. Indicated airspeed at the time was reported to be about 55 knots. The pilot subsequently advised that the roll into the turn was normal, but he was unable to level the wings again, even with full opposite aileron. The aircraft continued descending in a wing-low attitude and struck the ground about 250 metres before the threshold of the strip. Investigation revealed no evidence of any pre-impact defect or malfunction of the controls, and atmospheric conditions at the time were reported as being stable. When the sink was encountered on the downwind leg, the pilot had modified his circuit by flying closer to the strip. As a result, the angle of bank required for the base turn was steeper than normal. It was considered probable that the aircraft had stalled during this turn onto base, with insufficient height remaining to allow the pilot to recover control.

The aircraft was being operated from a clay pan strip on a dry lake bed. There had been no rain for approximately 48 hours and the pilot had flown his aircraft from the strip twice in that period. On each occasion he had taxied along the strip to the west and taken off into the east. However, on this occasion, he was departing to the west and the take-off run was along the section of strip used during the previous taxying. The pilot stated that during the take-off roll, the aircraft appeared to break through the clay surface crust and drag to one side. He said that he reduced power and attempted to bring the aircraft to a full stop before it ran off the side of the strip. However, the nosewheel broke through the surface and bogged in the soft clay causing the aircraft to overturn.

The pilot was taking three friends on a local sightseeing flight. He calculated that the aircraft would be close to maximum all-up-weight and from the Aircraft Performance Chart, concluded that a strip length of 700 metres was required with 9 degrees flap selected. He had earlier used a vehicle to measure the ALA length as 900 metres. Witnesses reported that the aircraft became airborne about three quarters of the way along the strip, flew level for a time, and slowly drifted left before climbing sharply over a row of trees. At this point the left wing dropped so the pilot retracted the flap and applied right rudder. He did not retract the landing gear. The aircraft descended and struck the ground right aileron first before skidding left through some 140 degrees. The nose and right main landing gear were torn off. The investigation revealed that the aircraft was approximately 5 percent above maximum take-off weight. The Aircraft Peformance Chart indicated that for the prevailing conditions, the required strip length was 975 metres. The strip itself was 800 metres long. An inspection of the aircraft did not reveal any faults that may have contributed to the occurrence.

Circumstances:

This was the student's first session on practice forced landings. The instructor demonstrated a forced landing approach and then positioned the aircraft for the student to practice an approach. The instructor intended to demonstrate to the student the dangers of trying to stretch the glide. The approach was flown by the student into wind with full flaps set, descending to a low height with the speed reducing to 55 knots. The student failed to respond to the instructor's call to watch the airspeed. The instructor took control, applying full power, but too late to avert the descent. The aircraft port wing tip contacted a bush, and the resulted ground contact caused the nose gear to collapse. The instructor estimated the wind as from the north-west at 15-20 knots and thought there was probably wind shear at low level, which contributed to causing the ground contact.

It was reported that the flight proceeded normally until during the flare. The glider was lined up with the strip, but during the hold-off it drifted to the right and touched down on the edge of the marked, 50 metre wide strip. The landing roll continued off the runway and the starboard wing struck a tree 20 metres from the edge of the strip. The landing was conducted in 4 to 8 knot crosswind conditions. During the hold-off the student pilot applied excessive rudder when aligning the aircraft with the strip prior to touchdown.

The more experienced pilot was occupying the rear control position, which did not have tail rotor control pedals, while another pilot flew the aircraft. During the approach to land the pilot in the rear seat became concerned when the airspeed decayed and he pushed the cyclic control forward to initiate a go around. The aircraft yawed to the right, control was lost and the aircraft struck the ground heavily, coming to rest on its right side. The inexperienced pilot occupying the front seat had been surprised when the rear seat pilot had taken control during the approach. Although he had been instructed to apply left pedal, it is likely that his delay in doing so, prevented control from being regained before the helicopter struck the ground. Inspection of the aircraft revealed that forward cyclic control movement was limited by incorrect rigging. This may have also contributed to the loss of control.