The helicopter was lifting an industrial straddle platform from the top of a large, 300 foot high, cooling tower at an electric power station. As the helicopter took up the load, the sling-rope snagged on a small lug on the right landing gear skid. The 420 kilogram load, hanging from the right skid, caused the helicopter to bank rapidly to the right. During this rapid bank, one end of a 2 metre long plastic pipe, held by the crewman at the right rear doorway, contacted 3 of the main rotor blades. Within less than 5 seconds the rope unsnagged from the skid with a sudden jolt as the load positioned itself at the full extension of the rope beneath the cargo hook. Simultaneously the pilot regained a level attitude but found that the helicopter was already descending slowly, under control, within the approximately 30 metre wide opening of the top of the cooling tower. Because the pilot feared that the "jolt" had been possible damage sustained by the helicopter, he continued the descent gently towards the inside base of the cooling tower. A few metres above the base, the pilot jettisoned the load which subsequently damaged the inside of the tower. After jettisoning the load, the pilot landed the helicopter lightly on its skids inside the tower. The crewman got out and inspected the helicopter as best he could as the pilot kept the engine running. As no damage was seen the pilot carefully flew the helicopter out of the tower and landed nearby as the crewman proceeded out on foot. There was nowhere inside the tower for the helicopter to safely shut down. The sling rope had been lightly attached to the skid before the flight by availing of a loop in the rope and one wrap of adhesive tape. The intention of lightly attaching the rope to the skid was to avoid the possibility of the rope being accidently caught on the rear protrusion of the skid during the lift. During the hook-up of the load, the helicopter encountered some turbulence which caused the helicopter to move forward of the desired hover position. During this forward movement, the thick rope slid aft along the right skid and a core strand of the rope snagged on a small lug which meant that the pilot could not jettison the load. At the time, the crewman was restrained at the right rear doorway. His task was to give manoeuvring directions to the pilot and to attach a hook on the far end of the sling rope to the load with a length of plastic pipe. The 420 kilogram load hanging from the right skid placed the helicopter outside the lateral centre of gravity limits for pilot control. Just as the helicopter banked rapidly right, the straddle platform lifted clear of the tower long enough for the helicopter, with the load still dangling from the right skid, to move into the stack opening where a slow descent commenced in a slight downdraft. During the preflight planning, the pilot and the crewman did not consider it possible for the thick rope to snag on either of the 2 small lugs which are designed for the attachment of ground handling wheels. The use of the adhesive tape held the rope close enough to the top surface of the skid for the rope to come into close proximity with the lugs.

Circumstances:

The purpose of the flight was to revalidate the Night VFR rating of the pilot under check. The pilots intended to conduct several circuits and then carry out a short navigation flight. The flight apparently proceeded without incident during the startup, taxi, and take-off from runway 12. The tower controller reported that he then saw the aircraft initiate a turn as if to fly a right circuit, contrary to previously acknowledged directions for left circuits. When this was queried by the tower, the crew confirmed that they intended to carry out a left circuit, and the aircraft was then seen to turn left. This was the last sighting of the aircraft by the controller as he then transferred his attention to other aircraft. When the aircraft later failed to reply to calls from the tower, a SAR phase was declared and this later developed into a full scale search for the aircraft.

The wreckage was discovered some hours later. The direction of take-off had been to the south-east, away from any ground lights, and on a moonless night. This resulted in no natural horizon being available to the pilots. A partial electrical power failure in the city and surrounds of Alice Springs occurred prior to the aircraft taking off and a total blackout occurred after the time established for the crash. While the reduced area of the ground lights pattern was judged not to have contributed to pilot disorientation by a reduction in visual cues, this unusual phenomenon may have caused the diversion of attention of one or both pilots. However, no positive conclusions could be drawn. The subsequent investigation revealed that the aircraft had crashed with the pilot-under-check at the controls. It had passed through the top of a tree before striking the ground at high speed, in a left wing low configuration. The landing gear and flaps were retracted.

Ground impact had almost totally destroyed the forward fuselage and cockpit, and the aircraft came to rest inverted some 100 metres after ground contact. The engine had been dislodged and was found about 200 metres beyond the fuselage. Detailed airworthiness inspection failed to detect any fault or anomaly in the aircraft which could be considered to have contributed to the accident. The total night flying experience of the check pilot was some 37 hours, of which six hours had been flown in the last 90 days. However, he had successfully completed a Night VFR revalidation flight for another pilot twelve days prior to the accident and flown some two hours at night three days before the accident. The pilot-under-check had only 14 hours total night flying experience and had not flown at night for 25 months. The conclusion was drawn that loss of control of the aircraft occurred for undetermined reasons at an altitude that was insufficient to effect a recovery.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. Both pilots had low levels of night flying experience.
2. There was no natural horizon available to the pilots.
3. For reasons undetermined, there was a loss of control of the aircraft at an altitude insufficient for recovery.

Circumstances:

On the flight to Bathurst Harbour immediately prior to the accident the pilot-in-command occupied the left pilot seat, and the co-pilot occupied the right pilot seat. Shortly after take-off on that flight the pilot-in-command handed over control of the aircraft to the co-pilot who was very experienced on tailwheel aircraft. The co-pilot landed the aircraft at Bathurst Harbour without any problem. After a short time sightseeing the party boarded the aircraft for DEPARTURE. The copilot was again handling the controls. Taxiing and the initial take-off run appeared normal but when the tail was raised the aircraft swung to the left. The take-off was discontinued but directional control was not regained. The aircraft left the strip and came to rest in a peat bog a short distance further on. After the accident, the co-pilot's rudder pedals were found to be in the stowed position which disconnects them from the rudder control system. It was not determined when the pedals were put in the stowed position, but it was determined that the co-pilot had not been briefed on the rudder pedal stow system.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1 Inadequate preflight inspection carried out.

2 The co-pilot was not briefed on the rudder pedal stow system.

3 Take-off was attempted with the rudder pedals stowed. 4 Loss of directional control on take-off.

Circumstances:

The aircraft was returning to Bankstown at the completion of a cargo charter flight. Take-off from runway 35 proceeded normally until the aircraft reached a height of about 90 feet when severe wind shear was encountered, resulting in a high rate of sink. The pilot was unable to prevent the aircraft from settling back onto the runway with the landing gear retracted. The prevailing conditions were conducive to the formation of mechanical turbulence in the lee of nearby mountains. At the time of the accident, it was reported there were large fluctuations in the wind velocity at Wollongong aerodrome.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The aircraft encountered severe wind shear at a critical stage of the take off and lacked the performance to prevent a collision with ground.

The pilot who was flying the aircraft occupied the left seat. He was being endorsed on type and it was his second flight in the aircraft. After DEPARTURE from Bankstown the aircraft was flown via the training area to Camden where it was intended to conduct circuit training. On the second circuit, the landing gear was reported to have extended normally and an indication of three green lights obtained. During the ground roll, following a normal landing, and before the instructor called for the pilot to continue with the touch-and-go, the right wing began to settle as the right main gear retracted. The instructor took control and brought the aircraft to a halt on the runway. Both the left main and nose gear legs remained fully extended. He said that he selected the gear lever to the down position when the right wing commenced to drop. An examination revealed the right main gear jack upper attachment had detached. It indicated the down side of the jack was pressurised whilst there was weight on the wheel and the overcentre lock was not made. This is consistent with the landing gear having been momentarily selected up during the landing roll and then selected down again. No mechanical defects were discovered during repairs to the aircraft which might have resulted in inadvertent gear retraction. The instructor had briefed the pilot under going training that he, the instructor would raise the flaps during the ground roll on touch-and-go landings. The PA 23 aircraft has the flap selector on the left side of the throttle quadrant and the landing gear selector on the right side; the reverse layout of most light aircraft equipped with retractable gear.

The aircraft was cruising at 6500 feet; the mixture had been leaned and the engine was operating normally. The pilot then reported that the engine note changed although all engine indications were normal. Approximately five minutes later the engine coughed and spluttered and started to lose power. The loss of power was reported to be rhythmic in nature, a few seconds of power followed by a like period of loss of power. The pilot turned the aircraft towards the DEPARTURE point and completed trouble checks, but these checks did not rectify the malfunction. It became apparent that the DEPARTURE strip could not be reached so the pilot turned south to intercept a dirt road he knew was in the area. The dirt road was located and with the stall warning sounding he selected full flap and turned to line up with the road. During the turn the aircraft grazed the top of a seven metre high tree. The aircraft then stalled onto the road from a low height. The nosewheel collapsed and the aircraft nosed over onto its back. Since there was no suitable terrain for a forced landing within gliding distance an accident was inevitable. Despite extensive examination of the engine and its components, no defect that would have caused a partial or total engine failure was found.

Circumstances:

The pilot had not landed at the airstrip previously. He made his approach to the 650 metre long airstrip which had a slight uphill gradient in the landing direction. On final approach the aircraft was undershooting and the pilot applied power. Touchdown occurred at the start of the airstrip and the wheel marks showed that all three wheels had touched down together. Immediately after touchdown, the nose gear collapsed, and the aircraft overturned. The distance from the touchdown point to where the aircraft came to rest was 25 metres. The nose gear collapse was caused by an overload failure of part of the downlock mechanism. In addition, the left main gear leg was bent upwards. This damage was consistent with a heavy landing.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The pilot misjudged the final stages of the approach.

Circumstances:

Nearing the completion of a survey flight over a mining prospect, the pilot asked the passengers if they would like to see a crop-dusting manoeuvre. As the passengers had no objection, the pilot flew the helicopter through a steep 180 degree climbing turn to the left from a height of about 300 feet. During recovery from the ensuing dive, the aircraft struck the ground heavily and came to rest inverted. The surviving passenger was thrown from the aircraft after the initial impact. There was no evidence of any mechanical defect in the helicopter which may have contributed to the accident.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The pilot attempted a manoeuvre at a height from which he was unable to recover safely.

Circumstances:

The pilot did not submit flight plan details, but departing Dubbo he advised tracking for Goulburn. No further communication was received from the aircraft, although there was evidence to suggest an intention to proceed to Bega with an intermediate landing at Wollongong. Approximately 80 minutes later, witnesses in the Fitzroy Falls area observed an aircraft fitting the description of VH-MCO, flying very low in various directions, at times obscured by cloud which had enveloped much of the area's higher terrain. Witnesses later heard a noise which caused them to believe that the aircraft had crashed. The area at the time was under the influence of a moist south easterly air mass, with cloud and showers along the coast and adjacent ranges extending to the western slopes of the Great Divide. An extensive air and ground search located the aircraft almost 48 hours later, approximately 100 feet below the level of a ridge. The aircraft had struck trees, which removed the right wing and outer left wing, before coming to rest under a large over-hanging rock ledge. The aircraft was reduced to non-survivable dimensions. There was no evidence of any pre-impact defect affecting the aircraft, and the damage sustained was consistent with the aircraft being in controlled flight at impact. No evidence was found to indicate that the pilot was either qualified or experienced in the conduct of flight in Instrument Meteorological Conditions.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The pilot exercised poor judgement by continuing flight into weather conditions in which he was not able to maintain the visual reference necessary to ensure adequate terrain clearance.

The flight was to survey stock and cull buffalo in an area south-west of the station homestead. After the helicopter failed to return by nightfall, the authorities were notified and a search initiated. The wreckage was located three days later. On-site investigation revealed that the main rotor blades had clipped some small upper branches on a 14 metre high tree before contacting the ground 19 metres further on. The helicopter impacted the ground while banked about 35 degrees to the right and in a nose down attitude of about 35 degrees, but with a flight path substantially closer to horizontal. It then rolled to the right and came to rest against a tree. A severe fire destroyed the cabin/fuselage area. A detailed examination of the engine was not possible because of the extent of fire damage. However, no indication of failure of any major component was noted. Damage to the main rotor blades and ground impact marks from the blades indicated that the blades were being driven by the engine at impact. The state of the tail rotor system indicated that it was intact and also under power at impact. The branches struck by the main rotor blades prior to impact were of insufficient size to have affected the blades or their flight characteristics. The attitude of the helicopter at impact was uncharacteristic for a rotary winged aircraft and indicated that it might not have been under control during the final stages of the flight. This could have been caused by a flight control problem or by some form of pilot incapacitation. Post-impact fire damage to the cockpit/fuselage section precluded a complete examination of the flight control system. No assessment could be made as to the likelihood of pilot incapacitation. A broken engine cooling fan drive belt was found between the tree struck by the main rotor and the initial ground impact point. The other belt was located within the wreckage in its correct position. It could not be established whether the belt was broken and thrown from the helicopter during the impact sequence or whether the belt fell from the helicopter prior to impact. In another recent accident involving the same type of helicopter, the blades on the engine cooling fan had failed. One blade had been thrown against the collective pitch control rod, almost completely severing the rod. Had fan blade failure occurred in the subject accident, (the broken drive belt could indicate this), and a collective pitch or cyclic control rod been struck and severed by a blade, loss of control of the helicopter could have resulted.