The aircraft was approaching to land after completing a handling display during an Open Day at RAAF Richmond. At an altitude of about 800ft, on the base leg for runway 28, both engines stopped simultaneously and without warning. As there was insufficient altitude to reach the field for a power off landing, the flaps and landing gear were retracted and a successful forced landing carried out into a cleared field short of the airfield. The crew evacuated the aircraft without injury.

A subsequent investigation failed to positively determine the cause of the simultaneous stoppage of both engines. A large quantity of fuel remained in the tanks and no defects were found with either of the engine fuel systems. The engine ignition systems were tested and functioned normally after the accident.

The design of this aircraft, as with other ex-military multi-reciprocating engine types, includes a master ignition switch. The switch is guarded, and when turned off results in the termination of ignition to all engines simultaneously. The switch was removed from the aircraft after the accident and subjected to extensive testing, including vibration tests, but could not be faulted. It was noted however that ignition isolation resulted with only a small movement of the switch from the ON position.

The most likely reason for the sudden stoppage of both engines was movement of the master ignition switch from the ON position, possibly as the result of vibration or by a crew member inadvertently bumping the switch prior to landing.

SAFETY ACTION

The Bureau of Air Safety Investigation drew the attention of the Civil Aviation Safety Authority to the fact that master ignition switches may still be fitted in older ex-military multi piston-engined aircraft, such as DC3s, on the civil register.

The sixty year old student pilot was authorised for additional solo practice. His intention was to fly a circuit and then fly around the training area for a while. On the first landing, he encountered a 5-knot crosswind from the left with a small wind gust at about the time of level off/touchdown. The aircraft touched down, bounced back into the air twice and then landed nose down heavily enough to break the nosewheel assembly.

In hindsight the pilot advised that he should have performed a go-around after the first bounce but at the time everything seemed to happen very quickly.

The pilot was conducting a night freight flight from Launceston to Hobart and return. He reported that during the approach to Launceston runway 32L the hydraulic pressure was normal, and the landing gear and flap selection was normal. The landing gear indicated three greens on extension and on short final. The throttles were closed in the flare and a nose high touchdown was made on the main landing gear. The nose gear was lowered and braking commenced for an anticipated turnoff onto taxiway 'Bravo'. The pilot reported that just before turning off, the propellers were put in fine pitch and, as he was reaching for the right engine fuel pump switch, the aircraft rolled to the right, the landing gear warning horn sounded, and the sound of the right propeller striking the tarmac was heard. The pilot reported that at this point he observed only two green landing gear lights, and the landing gear handle was down. He then retracted the flaps and put the safety pin in the gear selector lever.

Visual inspection showed that the right main landing gear had retracted backwards, and the aircraft was resting on the right wing tip, the lower fuselage and the right propeller. When the aircraft had been righted and hydraulic power was applied, the right main landing gear extended and locked normally.

After the aircraft had been recovered, maintenance investigation did not disclose any anomaly with the landing gear and its associated systems that could have initiated a retraction of the right main landing gear. The main landing gears are locked down by the over centre action of a horizontal brace that can only be broken by selecting the landing gear up, coupled with the application of hydraulic pressure.

Anecdotal evidence from the Aero commander service centre was that retractions had occurred to other aircraft while on the ground. Inadvertent gear up selections had been made, and when the aircraft had passed over small ground undulations sufficient to remove some of the weight from the landing gear and allow hydraulic pressure to break the over centre lock, the gear had retracted.

The landing gear is hydraulically activated from a selector on the lower right instrument panel. A pilot activated mechanical lock is fitted to stop inadvertent landing gear retraction. The lock lever is lifted and then moved to the left to place a pin across the selector lever to inhibit its movement.

The pilot on this flight had chosen never to use the mechanical lock because he considered that to remove the lock during a go-round would be an additional distraction during a period of high workload.

The pilot could not offer any explanation as to why the landing gear retracted. He said he could not recall having touched the selector lever. He was not employed full time as a pilot and had done a day’s work at his full time job the day before the accident. He had 5 hours sleep before commencing duty at 0230 and advised that he was well aware of the phenomenon of micro sleeping and was familiar with the flight routine having done many similar flights over the last 10 years.

Microsleeps are brief periods of sleep, usually lasting for a few seconds, when brain function is equivalent to the upper levels of sleep. The person having a microsleep can have their eyes open, but the incoming environmental information is not being processed. Therefore, external information is not being registered or perceived by the brain. These microsleeps are often seen in people who are fatigued or suffering from sleep loss.

The time of day a person wakes can also effect their performance. Waking prior to 0600 has been shown to degrade human performance.  Due to circadian functioning of the human body there are two particular times of the day in which performance is lower even without sleep loss.

The period 0300 to 0500 is a circadian low point for temperature, performance, and alertness. During this period the brain triggers sleep and sleepiness. Performance and alertness can be degraded during the nocturnal window, which is the period from 0200 until 0600.

The investigation did not disclose any problems of a mechanical nature that would have allowed the landing gear to retract. The flight was conducted during the critical period of the circadian rhythm and the nocturnal window. The investigation could not positively determine whether the pilot’s performance was affected by these factors.

Maintenance personnel reported finding significant damage to the left main landing gear, as the aircraft was being loaded for the return sector of a charter flight. The nature of the damage was consistent with a previous heavy landing. The two pilot operating crew advised that the previous flight sector was uneventful with a normal landing. A company investigation has been unable to determine when the damage occurred. The aircraft was removed from service for repair.

The pilot inspected a clay pan prior to landing but did not notice a washout from recent rains. During the landing roll the pilot saw the washout but was unable to stop the aircraft in time. The aircraft entered the depression at relatively low speed. The nose gear collapsed, and the propeller struck the ground.

The pilot reported that the Beech 200 King Air was passing through FL230, on descent from FL270, when he heard a loud bang. He advised ATC that both he and the sole passenger had donned oxygen masks as a result of a sudden loss of cabin pressurisation.

A post flight inspection of the aircraft found that the rear entrance upper latch hook had failed, permitting a loss of cabin pressurisation. The hook is an item with a replacement life of 12,000 flight hours. The failed door latch hook was reported to have completed 4704.5 hours, and 4295 pressurisation cycles, since new.

Failure analysis of the door latch hook found that the failure was caused by the growth of fatigue cracking, initiating from the inner radius of the hook. Subsequent crack extension was by a stress corrosion mechanism. 

Several factors were considered to have contributed to the failure of the hook well before the expiry of its designated safe life, including: - a surface irregularity created during machining of the hook;

- fatigue crack initiation from that machining irregularity;

- lack of corrosion protection of the door latch hook; and

- stress corrosion from prolonged exposure to a corrosive environment.

SAFETY ACTION 

The Bureau of Air Safety Investigation issued Safety Advisory Notice 970071 which drew the attention of the Civil Aviation Safety Authority to the fatigue failure of the hook.

The Bell 206 helicopter was engaged in aerial spraying of a property. The pilot had earlier carried out a ground inspection with the landowner to confirm the areas to be sprayed, and to identify obstacles. He then conducted an aerial survey before commencing spraying operations.

Because one of the treatment areas contained powerlines, the pilot decided to spray this area first. He planned to work from east to west, spraying on northerly tracks. This required the helicopter to descend over powerlines crossing the southern end of the treatment area. The height of the powerlines increased towards the western edge of the treatment area. Light coloured shade cloth covered part of the northern section of the area, forming a visual backdrop to the powerlines for much of their length.

The pilot descended to commence the 12th and final spray run along the western boundary, an area which did not have a shade cloth background, making the powerlines less distinct. He failed to notice the increased powerline height, which resulted in the helicopter, travelling at about 20 kts, colliding with a powerline at a height of about 30 ft.

A powerline passed between the landing skids and the fuselage, striking the forward cross tube. The helicopter pitched down, resulting in the main rotor blades slicing off the tail boom as the main rotor assembly separated from the mast, before the fuselage struck the ground. The pilot reported that the engine continued running after ground impact but there was no fire. Protected by a full safety harness and helmet, the pilot was able to escape from the wreckage with the assistance of a bystander. The helicopter's Emergency Locator Transmitter did not activate.

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.