The pilot reported that on arrival at Nebo the wind direction was variable at about 10 knots but favouring a landing towards the north. The pilot said that he joined crosswind and flew a left circuit for the northerly runway. After the aircraft was established on final approach at about 80 knots, full flap was selected and airspeed was reduced to between 55 and 60 knots. The pilot stated that as the aircraft reached flare height with the right wing slightly down to compensate for crosswind, power was reduced, and the aircraft contacted the runway heavily. This was followed by a further two impacts and the aircraft veered off the sealed runway. After control was regained, the aircraft was taxied back onto the runway and shut down. The landing impact caused permanent deformation of the rear fuselage and damaged to the nosewheel strut. The damage was not noticed until some time after the aircraft had been flown back to Cloncurry. The aircraft was fitted with a Narco 10 Emergency Locator Transmitter, but it was not activated by the heavy landing.

This was the pilots first flight in a Cessna 206, and although correctly endorsed under the group endorsement system, he had no previous training or experience on this particular aircraft type.

The accident was a direct result of the approach being made at an excessively low airspeed, and inappropriate flying technique.

The pilot was flying parachute operations from Bridgewater airstrip where there were two grass strips, an 1100 metre east west strip and a 700 metre north south strip. Occupants in a house to the west, off the end of the east west strip, were holding a function and had requested in writing that the parachute aircraft avoid overflying for the day to prevent the nuisance of noise. The pilot decided to comply with the fly neighbourly request and use the shorter north south strip.

After all four parachutists had exited at 3,500 ft the pilot joined for a tight right circuit for a landing to the north. Although he was high and fast on final, he persisted with the approach in an effort to avoid wasting valuable flight time. At the time, the wind was estimated to be a southerly at about 5 knots, the grass was wet, and the aircraft was light. With full flap and airspeed about 10 knots higher than desirable, the aircraft touched down hard well into the strip. For a moment the pilot considered a go-around but quickly rejected the idea for fear of colliding with marked powerlines immediately north of the strip beside a road. He braked hard but there was little affect due to wet slippery grass. He attempted a ground loop but to no avail.

The aircraft overran the strip, crashed through a farm fence, passed under the powerline, crossed a sealed road, penetrated another fence and came to rest about 40 metres beyond the airfield boundary. During the overrun the nosewheel assembly collapsed and the propeller struck the ground. The operator advised that there was no pressure on the pilot to hurry. The pilot gave the impression that he was so keen to please that he inadvertently placed himself in a situation beyond his level of flying ability.

When the aircraft landed, there was a crosswind from the right at about 10 kts. After a ground roll of about 300 m, the pilot elected to retract the flaps before commencing braking. Because of the crosswind, he was looking ahead of the aircraft to maintain directional control and inadvertently selected the landing gear control to the UP position. The landing gear retracted, and the aircraft slid on its belly for a further 300 m.

FACTUAL INFORMATION

The aircraft departed Broome on a short-notice charter to transport seven passengers from Derby to Cadjebut. The flight to Derby was uneventful and the passengers were boarded for the trip to Cadjebut. Apart from a small amount of surging from the right engine after start, the start, taxi and line up were normal. The pilot assessed the surging to be the result of low RPM after start and noted that the surging disappeared as RPM increased. He saw no discrepancies during the magneto checks on taxi.

No problems were encountered in the take-off until about 150 ft above ground level, when the pilot assessed that the right engine had failed. The landing gear was already retracted and the pilot commenced emergency drills for an engine failure after takeoff. He stated that there was insufficient time to feather the propeller and that the aircraft did not climb. It eventually impacted the ground and slid to a stop over mud and through low mangrove bush.

The passengers and pilot evacuated the aircraft. After the pilot had notified Air Traffic Services that the aircraft had crashed, he made the aircraft safe, and he and the passengers walked to the airport.

An on-site inspection did not reveal any defects or circumstances which could have contributed to an engine power reduction or the subsequent landing on the mud flats. Impact marks on the ground from the propellers supported the contention that the right engine was not delivering the same power as the left engine. The strike marks indicated that the right engine RPM was approximately half that of the left engine at initial impact with the ground.

The right engine was transported to Perth where it was successfully ground-run on an engine rig. The engine was subsequently dismantled, and extensive tests were performed on components which could have contributed to the perception by the pilot and several of the passengers that the engine had failed or had significantly reduced its power output. These tests centred mainly on the turbocharging, electrics and the fuel systems. Anomalies were only discovered in the dual magneto. However, the anomalies could not be directly connected to the power reduction.

The reason for the power reduction thus remains undetermined.

The aircraft was at, or marginally over, the maximum weight for take off when the power reduction occurred. The density altitude when the pilot commenced his emergency drills was about 2,000 ft and the pilot had not been able to feather the right propeller before the aircraft impacted the ground. The pilot operating handbook performance data suggested that with the right propeller feathered, the aircraft may have been able to climb at a rate of about 180 ft/min under ideal circumstances. The handbook does not provide information on the effect of not having a feathered propeller on the inoperative engine.

Emergency locator transmitter

A NARCO ELT10 was fixed in the rear of the fuselage and was correctly armed. The ELT did not activate, probably due to low-impact forces on the mud flats. The beacon was not needed as the pilot made radio contact with a flight service officer and the crash was observed by another aircraft.

ANALYSIS

Studies have shown that the combination of high weight, high density altitude and added drag from an unfeathered propeller can all reduce the climb performance of a light twin-engined aircraft in the event of an engine failure. Results of some of these studies were publicised during the 1996/97 Civil Aviation Safety Authority Flight Forum Series and the results indicated that an unfeathered propeller could reduce the rate of climb on a representative PA 31 by between 100 and 200 ft/min. It therefore follows that this aircraft was unlikely to have been able to maintain a positive rate of climb if the engine completely failed.

Although it is not known to what extent the engine power was reduced, the propeller marks indicate an RPM reduction in the order of 50% from take-off RPM, which suggests a substantial loss of useful power and possibly a windmilling propeller. This, and the performance data above, would probably explain the inability of this aircraft to climb away.

The aircraft was taking off from an agricultural strip for a rice sowing flight, carrying 1,000 kg of rice seed. The aircraft became airborne momentarily before settling back onto the strip. The pilot was unable to stop the aircraft before it collided with a low fence and a contour bank.

There were active thunderstorms reported in the area at the time, and it is likely that the aircraft encountered adverse windshear during lift-off.

The aircraft was engaged in spraying operations over a crop of rock melons. The pilot had not previously sprayed crops at this farm. During one of the spray runs the right wing struck a thin metal pole located at the edge of the paddock. The pilot was able to maintain control of the aircraft and diverted to land safely at a nearby air strip.

The farmer who normally removed the steel pole had forgotten to remove it on this occasion or to notify the pilot of its location.

The 5 to 6 m high pole was constructed of 25 mm square steel tubing. The pilot later said that he saw the obstacle too late to avoid a collision.

The pilot stated that the helicopter was given a full daily inspection. The engine had full oil and there was approximately 55 litres of fuel on board. After start, the engine was kept at idle until oil temperature was about 75 degrees. the rotors were then engaged and warm up was continued at 2000 RPM and then 2500 RPM. The magneto check showed no rough running. After pre-take-off checks, the helicopter was brought to the hover and moved forward about 6 feet, then put back on the ground for about 3 minutes while a load was placed on board. The pilot stated that after checking that all nozzles were working and pre-take-off checks were complete, he brought the helicopter to the hover. At 3200 RPM the manifold pressure was 26 inches. Transition to forward flight was normal, and height and speed began to increase. At about 60 to 70 feet agl and about 40 knots the engine note changed, and the pilot noticed RPM had reduced to about 2700. The pilot lowered the collective and wound on full throttle. A landing straight ahead was carried out with some forward speed, and during the landing the main rotor struck the tail boom and severed it. The helicopter was fitted with an NARCO 10 Emergency Locator Transmitter, which did not activate during the heavy landing.

Subsequent examination of the engine failed to reveal any defect, but engineering opinion was that the engine malfunction was most likely due to a sticking valve.

FACTUAL INFORMATION

An international B747 was enroute from Singapore to Melbourne over northwestern Australia at flight level (FL) 350. The B747 was under the control of a Brisbane sector controller using procedural control. The Brisbane controller was a team leader and he had commenced work at 2300 EST. He conducted a performance check on another controller until 0200 at which time the other controller left the console for a break. The team leader continued operating the position for approximately another two hours. The team leader felt well except for a minor cold condition which had developed that afternoon.

Generally, the work at the sector, on the evening shift, could be divided into approximately three periods. The first period was from 2300 until 0100 and this was the time when departure and position reports for aircraft intending to transit the sector were mainly received from northern air traffic control centres. The period from 0100 until 0200 was when the boundary positions were received. The last period from 0200 to 0400 was when the aircraft actually entered the sector and the crews contacted the sector controller. On the day of the incident the last period had finished at approximately 0300.

The B747 had been cleared to operate at FL350 and the crew had requested a preferred level of FL370 after 0320. The crew of the B747 reported their position at Curtin at FL350 and with an estimate for PAVKO of 0336. The team leader co-ordinated the position report with a Melbourne sector controller. PAVKO was the point at which control of the aircraft would be transferred from Brisbane to Melbourne air traffic control. The team leader intended to approve the crew of the B747 to climb to the higher level and to co-ordinate the level as FL 370 with the Melbourne controller. However, the team leader co-ordinated the level as FL350. The Melbourne controller incorrectly readback the level as FL370. Neither controller noticed the incorrect readback of the level. The Melbourne sector flight progress strip for the B747 indicated the aircraft was at FL350.

The team leader asked the crew of the B747 if they would be requesting climb to FL370. The crew replied that they would shortly like to climb to the higher level. The team leader instructed the crew of the B747 to climb to FL370 with a requirement to reach that level by PAVKO. The crew reported to the team leader when the aircraft left FL350 on climb to FL370. Normally, an aircraft's change of level is co-ordinated with the next air traffic control agency. The team leader, however, thought he had previously co-ordinated the higher level with the Melbourne sector controller and consequently did not conduct any further co-ordination.

The team leader instructed the crew of the B747 to contact the Melbourne sector controller at PAVKO. When the aircraft reached PAVKO the crew of the B747 reported their position and level of FL370 to the Melbourne sector controller. The Melbourne sector controller had expected the aircraft to report at FL350. There had been an error in co-ordination.

ANALYSIS

The team leader may have relaxed after completing the busiest part of the shift. Additionally, the timing of the incident, the time spent at the position overall, the possible higher level of awareness required for the check and his minor cold, probably combined to the extent that his ability to concentrate adequately on the task was impaired to some degree.

The Melbourne controller may have had an expectation of the B747 being at FL370 due to previous experience and the fact that it is a standard level for aircraft flying a south-easterly route.

The relationship between the body's circadian rhythm and performance is well known. In this incident, the fact that both controllers were working during the early morning and were also approximately halfway through their shifts would probably account for their lack of concentration and the consequent mishandling of the co-ordination.

The team leaders mind-set relating to his intention to approve the crew of the B747 to climb to FL370 would have pre-disposed him to hearing what he expected to hear from the Melbourne controller. This is despite the fact that the team leader co-ordinated the correct level at the time.

SIGNIFICANT FACTORS

1. The team leader had been continuously operating the position for approximately four hours.

2. The incident occurred at a time of the day when errors in human performance are more likely.

The pilot of the Piper PA31 had submitted details for an IFR flight from Lord Howe Island to Sydney via MAGOO and CHEZA at 9,000 ft, estimating CHEZA (60 NM from Sydney on the 084 radial), at 1835. At 1825 the pilot called Brisbane Centre for a clearance and was instructed to squawk transponder code 2350. The aircraft was identified at 50 NM from Sydney, on the 059 radial. This placed the aircraft some 22 NM right of track, within controlled airspace, and in potential conflict with an outbound Boeing 747.

The pilot of the PA31 later reported that he had been initially tracking on a bearing from the Lord Howe Island NDB. However, at the time of the incident he was unable to receive any Sydney radio navigation aids, and was navigating on time intervals and dead reckoning. The PA31 was squawking transponder code 2000 prior to calling Brisbane Centre. The crew of the B747 did not receive any Traffic Alert and Collision Avoidance System (TCAS) warning. Brisbane radar did not record any transponder returns from the PA31 prior to the aircraft squawking code 2350.

On arrival at Crocker Island, during the prelanding checks, the left main landing gear would not lock down. The pilot diverted to Darwin where emergency services were available. He performed the emergency landing gear extension drill, but the left main landing gear was still not indicating down and locked. The pilot flew past the tower for a visual inspection of the landing gear by the tower controller who advised that the landing gear "appeared normal". When emergency services were in place, the pilot landed. As the aircraft slowed on the landing roll, the left main gear collapsed.

Subsequently engineers discovered that the left side brace centre bushing had seized on its bolt thereby preventing the left main landing gear leg from locking down. The operator's chief engineer has formally advised the Civil Aviation Safety Authority of the mechanical fault.