The pilot gave a 'mayday' call advising that the aircraft had suffered an engine failure, and that he would be carrying out a forced landing. The aircraft was landed in a swampy area between trees which damaged both wings during the landing roll.

The pilot stated that he had not visually checked the fuel contents, or the security of the caps and access covers before departing Darwin as he had filled the right tank before the previous flight.

The fuel gauges did not indicate the expected amount of fuel even after the aircraft was established in cruise, but the pilot elected to continue to his destination.

About 6 km from the destination, with the left hand tank selected, the engine stopped. The pilot switched to the right tank, but the engine did not restart.

It is possible that the right tank was losing fuel from a faulty venting system on the flight into Darwin.

The aircraft was given an initial climb restriction of 3000 feet in the departure instructions. The aircraft was later noted on radar to be climbing through 3800 feet. The aircraft was then cleared to climb to planned cruising altitude of 6000 feet. When the incident was discussed with the pilot some three weeks later, he had no recollection of the event.

The pilot reported that the number 4 engine was shut down shortly after take-off. Fuel was dumped and the aircraft returned to land at Melbourne.

The engine was removed and forwarded to Singapore for rectification.

A report was received from the crew of a RAAF HS748 concerning the sub-standard operation of a Trinidad aircraft in the circuit area at Whyalla. The HS748 crew called entering the Whyalla MTAF stating their intentions. There was no response to that call. They then overflew the airfield and commenced a descent on the dead side of the circuit to join crosswind for a landing on runway 17. Descending through 1300 feet they observed a Trinidad on a reciprocal track about 200 feet higher. Repeated calls for the Trinidad to identify itself received no response.

Shortly afterwards the pilot of the Trinidad made a downwind call which incorrectly advised that the aircraft was making an approach for another runway. The HS748 crew stated that the pilot of the Trinidad did not appear to understand standard MTAF procedures.

The instructor was giving the pilot a type endorsement and this was to be the final circuit. It was thought the gear was extended on downwind with appropriate cockpit indications to confirm this. Just prior to touch down the gear horn sounded and the instructor called for a go around. Power was applied as the aircraft contacted the ground.

The landing gear legs were still up after the accident, but the gear doors had been open and were damaged. This was consistent with a gear down selection being made at the last moment.

The aircraft was parked on the aircraft loading area. There were flood lights on the southern side, but the light from these only dimly illuminated the northern side. After engine start the pilot turned on the taxi and landing lights and started to taxi towards the northern side. There was a taxi line along the northern side, leading out of the area in a westerly direction. This line was not seen by the pilot, possibly because he was changing the radio frequency selection from Clearance Delivery to Surface Movement Control.

The aircraft left the sealed area, tracking about north-west and ran onto the grass. This was outside the limit of the marked movement area. Realising he was now on the grass the pilot turned the aircraft left, but the right main wheel struck an exposed concrete slab. The right main gear leg collapsed.

The pilot did not follow the correct procedure while performing a Radar One departure from Essendon. Investigation revealed that the pilot flying was doing his first flight for endorsement onto the aircraft type. The PIC was busy monitoring the pilot flying in terms of aircraft handling and as a result he did not closely monitor compliance with the departure procedure. The pilot flying was not familiar with the Standard Radar Departure procedures out of Essendon.

Significant Factors

The following factors were relevant to the development of the incident:

1. The pilot flying was not familiar with Standard Radar Departure procedures out of Essendon.

2. The PIC did not properly monitor the pilot flying.

The aircraft was being flown to calibrate the stall warning device. The pilot closed the throttle and as the airspeed reduced to about 70 knots the propeller stopped. Attempts at restarting the engine were unsuccessful. The pilot elected to land on the beach where the aircraft struck soft sand. The right main gear collapsed and during the subsequent swing to the right the aircraft struck bushes at the edge of the beach.

External examination of the engine revealed that rotation of the crankshaft was rather stiff, however this could have been the result of striking the beach sand during the landing. The engine was not stripped as the owner indicated that he would not return it to service.

This accident was not subject to an on-site investigation.

The aircraft had operated a normal scheduled service, arriving in Adelaide early that afternoon. 100 litres of avgas was added to its fuel tank from the airport refuelling facilities for the return flight to Port Augusta.

The aircraft departed with the pilot and five passengers on board, but about five minutes into the flight, climbing through 4000ft, the pilot noticed the left-hand fuel pressure gauge flickering and immediately turned the left fuel boost pump on which momentarily restored the fuel pressure back to normal. Several seconds later the fuel pressure indication dropped below the red line (minimum pressure) and the engine began to surge and lose power.

The pilot commenced a descent and advised air traffic control that the aircraft was returning to Adelaide. His attention was now directed to the right-hand fuel pressure gauge which had also fallen to a low pressure. Turning the boost pump on failed to rectify the problem, and this engine also surged and lost power.

With almost no power available the pilot realised that the distance to Adelaide Airport was too far, so positioned the aircraft for an emergency landing along the coast. He attempted to gain more power by opening the throttles, but this only resulted in erratic surging from both engines with a further decrease in power.

It now appeared that the aircraft would not reach the shoreline, so the pilot shut down both engines and feathered the propellers to extend the glide. When a landing on the beach was assured, he prepared and briefed the passengers for the landing, and to avoid a group of people on the beach delayed extending the landing gear and flaps until the aircraft was clear of their position.

Because of insufficient time for the landing gear to fully extend, the aircraft touched down on the firm sand with the landing gear trailing and skidded for approximately 200 metres along the beach on its belly.

The pilot and passengers were uninjured, and the aircraft received some damage to the rear cabin area lower fuselage skin panels.

The aircraft had been carrying sufficient fuel for the flight, the fuel tank caps were correctly secured, and the fuel tank vents were not blocked. Fuel samples taken from the fuel tanker which had recently refuelled the aircraft showed that the correct type of fuel had been supplied and was not contaminated.

The fuel filters were removed and fuel samples taken from the aircraft for analysis. The filters were found to be blocked by a considerable amount of foreign matter restricting the fuel flow.

Analysis of the fuel samples and sediment indicated that there were no obvious contaminants present which may have been cause for concern.

The particulates present in the samples are always found during testing, being present in the environment and probably introduced during different stages of the fuel handling. The overall amount did not exceed the specification limits.

The particles present in the fuel would not have been responsible for blocking the filters on their own but would have resulted from the combined effort of a large quantity of individual particulates.

All fuel samples met the specification requirements.

This type of aircraft is unique in that it has only one interconnected fuel tank feeding both engines. Each engine has a 5-micron fuel filter, and a fuel vent system which can allow the ingestion of dust into the fuel tank when the aircraft is operated in dusty conditions.

The aircraft often operates through the channel countries of South Australia and Queensland, a lot of the time in dusty conditions. Refuelling is carried out using drum stock when contaminants could easily be introduced into the fuel system.

The rapid blockage of the fuel filters, which occurred after the aircraft departed, was probably the result of the aircraft fuel system being contaminated over a period of time with an accumulation of extremely fine particles which would have been difficult to detect during water drain checks, and settled forming a sediment at the bottom of the tank. These remained relatively undisturbed until fuel was added to the low level of fuel in the tank, stirring the particles into suspension. This may have concentrated the contamination so that the filters, already partially degraded by contaminants, were further degraded quickly to a point when fuel flow to the engines was severely restricted.

The inherent design weakness of the fuel system in this type of aircraft, including the very fine mesh filters which are intolerant to any fuel contamination, is well known amongst operators, including the operator of this aircraft, who over a long period of time have developed successful control systems and methods for minimising the problem. Immediately following this occurrence the operator instigated more stringent controls and instructions to its pilots concerning the fuel system, and improved quality control for refuelling operations, especially from drum stock.

The pilot reported that he was mustering a herd of cattle and that he was aware of a powerline on the far side of the herd. Without realising that he had crossed the powerline in timbered country, he descended the helicopter in open country to turn the cattle. As he was pulling away from the herd, the skids of the helicopter struck the powerline. The main rotor struck the tail boom and the pilot lost directional control. The pilot closed the throttle and the helicopter landed heavily.