Collision with terrain

The pilot commenced the take-off run and confirmed that full power was selected. At an indicated airspeed of 90 knots, he rotated the aircraft and waited for the performance instruments to indicate that a positive rate of climb and the single engine climb speed had been achieved. The pilot reported that the aircraft did not accelerate beyond an airspeed of 95 knots and a positive rate of climb was not obtained. He stated that he retracted the gear, to avoid having it snag the boundary fence, and then realised that the left engine was losing power and altitude was not being maintained. The pilot then closed the throttles and the aircraft landed in open country beyond the aerodrome boundary. An inspection of the aircraft did not detect any faults in the engines or other aircraft systems that could have contributed to the occurrence. An examination of the propellers indicated that both engines were delivering power at the time the aircraft struck the ground. The cause of this accident remains undetermined.

Following a dual check and a short solo flight, the pilot was authorised to conduct a soaring flight of not more than one hour's duration. The glider was subsequently launched from an aerotow after take-off into a light northerly wind. It was observed soaring in the vicinity of the aerodrome within an estimated height band of 3000 to 6000 feet above ground level. During the flight the wind on the ground changed to become a gusty south-westerly at about 10 to 15 knots. The shade temperature was 36 degrees Celsius and localised areas of turbulence were reported by other pilots.

The pilot did not return for a landing for approximately two hours, despite the pre-flight briefing. When he returned, the aircraft was positioned for a landing into the north, apparently without reference to the changed wind conditions. During final approach the glider was seen to pitch down into an almost vertical dive. It struck the ground some 200 metres before the strip threshold and came to rest inverted. Subsequent examination of the wreckage did not reveal any defect or malfunction that might have affected the pilot's ability to safely control the aircraft. It was apparent that the glider had been in a normal wings level approach configuration immediately before the pitch-down which occurred at a height of about 100 feet above ground level.

It was considered possible that the aircraft could have been affected by turbulence, or that the pilot may have suffered from heat stress and fatigue. However, insufficient evidence was available to enable the precise factors in the occurrence to be determined.

The pilot was engaged in a mustering operation on his own property. During the operation he saw a truck departing from the property. He had an urgent messsage for the driver, so he elected to land on a road near the truck's route which he knew was suitable as a landing area. During the landing roll the left wing hit a steel pole which was off the edge of the road. The pilot did not see the pole because he was landing to the East and the rising sun was in his eyes.

Prior to commencing the flight the pilot received a briefing on the meteorological situation. This briefing indicated that the flight under Visual Flight Rules (VFR) would not be possible over the route and that the conditions were unlikely to improve during the day. The pilot apparently decided to check the weather situation for himself and submitted a flight plan for a flight to Port Macquarie. The plan indicated that the flight would comply with VFR procedures. The aircraft departed Tamworth but failed to arrive at the destination before the expiry of the nominated Search and Rescue time (SARTIME). A land and air search was commenced, although the latter was initially hampered by poor weather conditions. No trace of the aircraft was found and the search was suspended after five days. Two days later the wreckage was located by an aircraft conducting a private search. The aircraft had flown into tall trees on the top of a 3500 feet high ridge line. It had been torn apart by the impact forces and the wreckage was spread over a distance of some 90 metres beyond the initial impact point. The investigation did not reveal any pre-impact defect with the aircraft or its systems which might have contributed to the accident. An analysis of the weather conditions in the vicinity indicated that the accident site was most likely covered with cloud. The pilot was probably flying in conditions of reduced forward visibility when the aircraft collided with the trees.

Circumstances:

The pilot completed some dual flying earlier in the morning in another pilot's gyrocopter. About 10 hours dual flying had been completed with this other pilot over recent weeks. He then decided to make a solo flight in his own single place gyrocopter. The intention was to fly eight to ten circuits and low passes along the airstrip to get the feel of the aircraft. The first circuit appeared to proceed smoothly at an altitude of about 250 feet above the ground until the turn onto final approach. When that turn was started the aircraft assumed a reasonably steep nose down attitude. Engine noise remained constant until the aircraft hit the ground tracking about 15 degrees to the left of the landing direction. A detailed wreckage inspection did not reveal any pre-existing defect that may have contributed to the accident.

Significant Factors:

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

1. The investigation did not determine why the aircraft hit the ground in the manner that it did.

The pilot was to conduct a charter with passengers from Sydney to Wollongong, Nowra, Canberra and return to Sydney, departing Sydney at about 10.00am. Earlier that morning he positioned the aircraft at Sydney and had it refuelled. When the passengers arrived he explained that the weather in the various destinations was very poor and that there was a possibility they may not be able to land. However, he was prepared to give it a try. As the passengers were pressed for time, they could not afford to take a chance with the weather and so they decided to drive. They told the pilot that if he could land at Wollongong later that day they would continue the flight with him. However, they impressed on him that there was no pressure for him to depart immediately as they would not be in Wollongong for several hours. After driving for a short time, the passengers decided that the weather did not appear as if it would improve, and believed that it would be better to complete the journey by car. They contacted the charter company by phone to cancel the charter, but the pilot had already departed. The flight to Wollongong appears to have proceeded normally where the pilot reported commencing an NDB approach, and would call again at a specified time. This was the last message received from the pilot. Witnesses on the ground at Wollongong, and on a yacht 20 nautical miles to the east of Wollongong reported hearing an aircraft flying at approximately 1000 to 2000 feet in the low cloud and rain. There were no other known aircraft in the area. Later that day a helicopter discovered wreckage debris in the sea, which was confirmed as being from the aircraft. The search was discontinued due to very poor weather and visibility, and cancelled two weeks later when further efforts failed to locate any trace of the aircraft.

The pilot had recently obtained a Commercial Helicopter Pilot Licence, and had been undergoing training for the issue of a cattle mustering endorsement. He had obtained permission from his employer to use the helicopter for a local flight. The approval was given on the understanding that operations were confined to normal procedures, and were not to include low flying. It was the pilot's intention to conduct two short flights, carrying two other persons on each occasion. The helicopter was given additional pre-flight inspections, following reports of vandalism to other helicopters in the area. No evidence of any vandalism was found and the pilot carried out a short solo flight to further verify the serviceability of the aircraft. The first two passengers then boarded the aircraft. About 30 minutes after DEPARTURE, the aircraft was observed operating, apparently normally, in a designated low flying area. It was then observed flying towards the south east at about 10 metres above the ground. The aircraft then entered a steep turn to the left, but after turning through some 200 degrees the main rotor blades struck the ground. The aircraft subsequently struck the ground heavily and cartwheeled around the rotor arc. A fierce fire broke out and engulfed the wreckage. A detailed technical investigation did not reveal any pre-impact defect or malfunction of the helicopter which might have contributed to the accident. There was also no evidence that the pilot had suffered any sudden illness or incapacity which might have affected his ability to control the aircraft. There was no known operational reason for the aircraft to be flown close to the ground, and it was possible that the pilot was demonstrating mustering techniques to his passengers. The wind at the time of the accident was from the south east at between 11 and 18 knots. The helicopter had been loaded near to the maximum allowable weight, and had not possessed sufficient performance to maintain level flight during the turn towards the downwind direction. The pilot had only limited experience in operations at high all-up-weight levels, and had evidently not realised the effect the increased weight had on the aircraft performance, particularly when turning downwind.

The aircraft was engaged in operating a night freight flight from Brisbane to Gladstone and Rockhampton. The pilot departed Rockhampton as a passenger in another company aircraft at about 2100 hours the night before the accident and was flown to Caloundra. He then flew VH-DIL to Brisbane and after arriving submitted a flight plan for the return flight to Rockhampton giving an estimated time of DEPARTURE Brisbane of 0230 hours. Before DEPARTURE, however, the pilot was required to await the arrival of another aircraft so that freight could be transhipped to his aircraft. DEPARTURE from Brisbane was made at 0301 hours and at 0400 hours the pilot reported the aircraft's position over Gayndah, the pilot was instructed to call on another radio frequency at 0410 hours. No further transmissions were heard from the aircraft. The wreckage was located two days later in mountainous terrain. The aircraft had impacted the ground in a near vertical attitude. Subsequent investigation did not reveal any fault with the aircraft or its systems that could have contributed to the accident. The day before the accident the pilot rose at about 0730 hours after spending the previous night and day at a friends property near Rockhampton. He spent the day at leisure at the property before returning to Rockhampton in the afternoon. After dining at his parents home he proceeded to the airport for the flight to Caloundra. Before departing Brisbane to return to Rockhampton the only sleep the pilot would have had was about an hour on the flight to Caloundra and possibly another short period at Brisbane Airport while waiting for his aircraft to be loaded.

Circumstances:

At approximately 1809, (23 minutes before last light) during final approach to landing at Carnarvon, the pilot noticed that the landing gear had not extended correctly. The aircraft remained in the circuit area whilst the pilot attempted to lower the landing gear using both manual and emergency methods. He also sought assistance from the company's, Perth based, duty pilot and Carnarvon based engineers. After exhausting all possible methods of lowering the gear the pilot decided to land with the landing gear and flaps retracted. The pilot rejected a landing on the sealed runways because he was apprehensive that it would cause unnecessary damage to the aircraft and could result in a fire. He considered landing in a riverbed (rejected by the Senior Operational Controller), alongside one of the sealed runways (the surface was unsuitable) and on one of the dirt strips. The pilot was offered a flare path on dirt runway 27 however, he declined and indicated that he would try to land using the available light. At 1856 (last light was at 1832) the pilot attempted a landing on runway 27. On late final approach the aircraft collided with a one and a half metre high levy bank, 270 metres short and 115 metres to the right of the threshold. The pilot was trapped in the wreckage for some time after the aircraft came to a stop. The landing gear problem arose when the left main landing gear would not lower. Examination of the aircraft revealed that both hinges fitted to the inboard landing gear door had fractured. The forward hinge had fractured as a result of fatigue and the rear hinge as a result of overload. The fatigue crack initiation had occurred at a sharp edged, prominent forging flash on the inner radius of the hinge and had grown over approximately 4000 load cycles. A similar fatigue problem had been identified on an earlier version of the hinge (part number 46653-00), however, regular inspections for fatigue cracking were discontinued when hinges with part number 47529-32 (as fitted to VH-DEG) were introduced in 1980. Similar fatigue cracking was found in the forward door hinge of another PA31 during the investigation. The fractured hinges jammed the left main landing gear mechanism and neither the normal or emergency extension systems could extend the gear. The pilot was apprehensive about wheels up landings. Much of his decision making was aimed at reducing the risk of fire and minimising the damage the aircraft would sustain during the landing. e.g. Selection of a dirt runway instead of the sealed strip, landing with flaps retracted etc. During the pilot's attempts to rectify the landing gear problem, and up until the time of his touchdown, he was subjected to considerable radio transmission traffic involving questions, directions and suggestions which distracted him from his primary tasks. The pilot indicated on at least two occasions that he was ready to land, however, each time advice and questions from the ground personnel involved overrode his intentions. When the pilot was asked if he wanted a flare path on runway 27 there was still some natural light available and he was intending to land. However, by the time he was able to make his final approach it was dark and he was unable to see the ground. Studies have shown that aircrew subjected to high levels of stress can suffer skill fatigue and cognitive task saturation, which in turn can lead to a breakdown in the decision-making process. It was apparent from the pilot's radio transmissions and the quality of the decisions made in the latter part of the flight that his information processing and decision-making abilities had been degraded by the stress of continuous radio transmissions and continuous, and sometimes conflicting, instructions. As a result, what should have been a relatively simple wheels up landing in daylight was turned into an extremely difficult wheels up landing at night. With the landing gear retracted the aircraft's taxi and landing lights were not available to the pilot.

Significant Factors:

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

1. Manufacturing defect. A forging flash created a stress concentration which led to fatigue cracking.

2. Inadequate inspection procedures. Previous inspection procedures introduced to disclose similar cracking were withdrawn on the introduction of later part numbered hinges.

3. Apprehension of the pilot. The pilot was apprehensive about apparently significant dangers of landing an aircraft, wheels up, on a sealed runway.

4. Inordinate interference in aircraft operations by ground-based advisors. The ground advisors input overrode the pilot's decision on a number of occasions with the result that a simple exercise became very complicated.

5. Cognitive task saturation and skill fatigue. The amount of information, advice and suggestions being passed via the radio communications system overloaded the pilot decision making abilities.

6. Improper in-flight decisions. As a result of task saturation, the final decision made by the pilot to attempt a night landing on an unlighted strip was incorrect.

7. The pilot did not see and therefore was unable to avoid the levy bank.

Recommendations:

That the Civil Aviation Authority give consideration to amending AD/PA-31/93, to include the later part number hinges (P/N 47529-32 and 46653-00 (steel) which were introduced by SB 682) for a repetitive inspection in addition to the inspection called up for Pre SB 682 hinges.

The pilot was attempting to bring the helicopter to a hover in the lee of a hill, but found that there was insufficient power to arrest the rate of descent. The aircraft struck the ground and rolled over. The pilot reported that the conditions were very windy. The helicopter was reported to have been operating normally prior to the accident. The pilot stated that in attempting to arrest the rate of descent he had inadvertently overpitched the rotors at an altitude from which recovery was not possible. This accident was not the subject of an on-site investigation.