Ditching

The aircraft struck powerlines while manoeuvering near the Bloomsbury airfield. It then fell to the ground on the edge of a small dam. Most of the aircraft was destroyed by fire but the empenage came to rest on a small boat moored at the edge of the dam.

During climb out from Dauan Island (Torres Strait), the helicopter suffered an engine power loss. The pilot placed the helicopter in autorotation from approximately 300 feet. Having heavily impacted the water, the helicopter sank and rolled inverted. The pilot and three of the four passengers escaped. The remaining passenger remained in the aircraft as it sank. One of the passengers who survived the ditching did not remain afloat and disappeared from the other survivor's view. The aircraft sank and has not been recovered.

The hang glider pilot was soaring off the cliffs east of the Cape Byron lighthouse where the nearest area suitable for a landing is Tallows Beach, several hundred metres to the south. The wind had been ESE at about 15 knots prior to a sudden arrival of a front passing through which changed the wind to a 20 to 25 knot southerly. Other hang glider pilots had landed prior to the arrival of the front which was not accompanied by any telltale cloud change. The hang glider pilot was soaring at about 500ft when the change came through and was unable to glide into wind to a beach landing. He landed in the surf and was apparently unable to extricate himself from his harness and drowned.

The above details were provided by the Hang Gliding Federation of Australia.

The helicopter was being flown from Ceduna to Parafield, with planned refuelling stops en route. It was initially refuelled with avgas carried in jerry cans, then later with super petrol (mogas) obtained from a service station at Iron Knob. The jerry cans used were reported to be clean, and the fuel uncontaminated. Prior to landing at Iron Knob, the pilot landed the helicopter on a clay pan and idled the engine for a short time to prevent possible overheating due to a reported partial oil cooler airflow restriction. It was refuelled with avgas at Whyalla and fuel drain checks were carried out. The jerry cans were also refilled and loaded onto the helicopter.

The radio transceiver fitted to the helicopter was unserviceable and the pilot had been using a handheld portable transceiver for communications. At Iron Knob he contacted Parafield Air Traffic Control (ATC) by telephone, advised of the radio problem, and of his intention to use the portable radio for his arrival at Parafield.

Before departing Whyalla, the pilot made a taxiing call which was recorded on the Whyalla Airport 'Avdata' tape. His initial track was over Spencer Gulf towards Port Pirie. The weather was fine with a strong north to north westerly wind at 20-25 knots, gusting to 35 knots, with a temperature of 31 degrees Celsius.

The passenger recalled that about five minutes after departing Whyalla, when the helicopter had climbed to approximately 1,000 feet, it suddenly turned left through 180 degrees, into wind, and the pilot advised him that they were going to ditch. The passenger said he had not noticed any change to the engine note, or any other problems prior to the helicopter turning, but during the descent he noticed that the cabin noise level had decreased, and he could now communicate with the pilot without using the intercom or shouting.

The pilot instructed the passenger (who had had some aeronautical experience) to make a 'mayday' call on the portable radio. The passenger was unsure of the frequency selected but believes that it was still tuned to the Whyalla mandatory traffic advisory frequency (MTAF). This call was not heard by any other aircraft or recorded on the Whyalla 'Avdata' tape. The passenger also used his mobile telephone in an unsuccessful attempt to contact his home, and Parafield ATC.

The passenger reported that the helicopter impacted the water in a nose down, left skid low attitude following a stable autorotational descent. The plexiglass bubble broke on impact, and the helicopter sank immediately. The pilot, who was knocked unconscious at impact, was released from his seatbelt by the passenger and pushed to the surface, where he quickly recovered. However, the pilot later drowned.

With this type of helicopter, following a loss of engine power, torque created by the rotation of the main rotor system causes the fuselage to turn left which can be corrected by pilot input through the anti-torque (tail rotor) system. A failure of the anti-torque system, with the engine still delivering power, would induce a turn to the right.

The passenger's recollections of the event indicate that the helicopter suffered a sudden loss of engine power, followed by a 180 degree turn to the left. The pilot corrected for this turning and controlled the helicopter in a normal autorotational descent.

Despite considerable search effort, the helicopter wreckage has not been located.

Neither the pilot nor the passenger was wearing a life jacket, as required by Civil Aviation Orders 20.11.5.1.1 (a) and 20.11.5.1.7 for overwater flights and there was no other flotation equipment on board.

Findings

1. The helicopter had a valid maintenance release.
2. The pilot was correctly licensed and endorsed on the helicopter type.
3. The avgas and mogas used to refuel the helicopter en route to Whyalla was reported to have been supplied in clean jerry cans.
4. The helicopter had been refuelled with clean avgas at Whyalla.
5. The passenger's recollection is consistent with the helicopter suffering a sudden loss of power about 5 minutes after take-off.
6. The pilot carried out a normal autorotational descent to the sea.
7. There were no life jackets or flotation equipment on board the helicopter as required by Civil Aviation Orders.
8. The helicopter has not been located, therefore the reason for the ditching cannot be confirmed.

Significant Factor

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

Following a probable loss of engine power the pilot was forced to conduct an autorotational descent to the sea.

The aircraft was tasked to carry out a marine pilot pick-up from a departing tanker. The flight was conducted by two pilots operating under night visual flight rules. Conditions were a moonless night with no defined horizon, no outside lighting other than from the ship, and a surface wind that was light and variable. The ship was steaming in a northerly direction at 12.5 kts.

The flight proceeded normally until the aircraft was established on final approach to the helideck. As the aircraft descended through 500 ft the rate of descent had increased to about 1,000 ft/min. Although the pilot in command increased main rotor pitch, the aircraft's rate of descent continued to increase until just prior to impact with the water.

Both occupants were rescued approximately 1 h after they evacuated the helicopter. The report concludes that the standard approach technique used by the pilots, coupled with the prevailing weather conditions, caused the aircraft to enter a high rate of descent shortly after the aircraft started its normal final approach to the deck.

The high rate of descent was probably the result of entry to the incipient stage of Vortex-ring state'. A lack of visual cues and inadequate management of cockpit resources prevented the crew from recognising the abnormal situation until the aircraft was well into the descent. Recovery action was commenced too late to prevent impact with the water.

On 22 November 1991 at 0912 hours Australian Central Standard Time (Greenwich Mean Time + 9.5 h), a Bell 214ST helicopter was ditched into the Timor Sea shortly after take-off from a floating production facility. The two crew and 15 passengers evacuated uninjured from the floating helicopter, prior to the right main flotation bag being punctured and the helicopter capsizing.

The report concludes that at a critical stage of the take-off, at an altitude of approximately 120 ft above the sea, one of the engines experienced a high-side speed excursion. This was followed by an aircraft main rotor speed increase which illuminated a cockpit indication warning that the aircraft main rotor speed was out of limits. The captain reacted to what he thought was an engine power loss by lowering the collective, which is the prescribed response to that situation, thereby unloading the main rotor which rapidly accelerated to 116.7%.

The electrical control unit of the ungoverned engine, sensing a power turbine overspeed, actuated the fuel sequence valve to shut off fuel to the engine. As the over speeding engine accelerated, the other engine, while attempting to compensate, decelerated to idle power because of the lowered collective command.

The captain's action in lowering the collective exacerbated the rapidity of the event, and because of insufficient aircraft altitude, there was not enough time for the engine still under power to pick up the load, or for the captain to take further corrective action to avoid a sea ditching. At the time of the emergency, the captain was demonstrating a take-off to his co-pilot.

The flight was planned from Deniliquin - Cootamundra - Bankstown with a time interval to Cootamundra of 96 minutes, and although the pilot indicated a fuel endurance of 300 minutes, the aircraft handling notes and an analysis of fuel consumptions based on refuellings since the aircraft left Sydney on 31 March, indicate that this figure was unrealistically high. The aircraft was being directed to Camden, when, at 1826 hours, the pilot reported that he was running out of fuel. The aircraft was ditched in Lake Burragorang.