VH-UZP departed Townsville on the Townsville-Collinsville track but was then cleared to track direct to Mackay. VH-JJY, a faster aircraft, departed Townsville six minutes later and climbed initially on the Townsville-Bowen track before also being given a direct track to Mackay. The aircraft were thus on converging tracks.

VH-JJY was subsequently cleared to divert up to 10 NM right of track to avoid thunderstorm cells. This brought the aircraft into potential conflict with VH-UZP, so the controller instituted a stepped climb procedure between the two aircraft. He then noted that VH-JJY was not diverting far off track so he cleared that aircraft to climb through the level of VH-UZP which by this time was level at FL210. The controller instructed VH-JJY to expedite climb to FL 220. However, VH-JJY then diverted further right of track (but still within 10 NM of track) and did not climb at the rate the controller expected. This resulted in a breakdown of separation standards between the aircraft. Recorded radar data indicated that when the aircraft were 3 NM apart, there was 200 ft vertical separation. The prescribed standard is 5 NM or 1,000 ft.

Neither crew was given traffic information on the other aircraft. The controller, on realising that separation standards could be infringed, gave the leading aircraft (VH-UZP) a heading change from 125 degrees to 140 degrees. This was not of sufficient magnitude to ensure that the separation would be maintained.

Significant Factors

The following factors are considered relevant to the development of this incident:

1. Weather avoidance considerations resulted in the aircraft diverting off track.

2. Appropriate separation standards were not applied following the diversion of VH-JJY off track.

The pilot had been spreading superphosphate in a paddock to the north of the strip. To get to the paddock the aircraft had to climb over hills. This was achieved with the assistance of updraughts off the hills. On the accident flight the pilot found the updraughts were not present and the aircraft was not climbing adequately. Concerned that he would not be able to clear trees ahead the pilot dumped the load and attempted to turn left. The aircraft struck a tree and spun to the ground. The pilot escaped from the wreckage, but the aircraft caught fire and was destroyed.

After flying through some heavy showers, the pilot detected a vibration in the aircraft. He knew that the main rotor abrasion tapes sometimes came loose in rain, and when he detected a performance loss, he suspected that loose tapes may have been the reason for the vibration. He decided to land to remove the tapes. With maximum power selected, the pilot could not arrest the sink rate during the approach for the run on landing, and the helicopter landed heavily and bounced. As a result of the hard landing, the main rotor blades severed the tail boom.

Damage to the main rotor blades was such that it could not be determined if the blade tape had lifted prior to the accident. No other defects were discovered that could have contributed to the loss of performance.

The pilot reported that after completion of the first heat of a pylon race, flying at 100 feet above the ground, the aircraft was climbed to 350 feet in preparation for landing. The throttle was closed to reduce speed and within about 15 seconds the engine began to run roughly. The pilot opened the throttle but there was no response from the engine. The aircraft was landed in a paddock.

Significant Factors

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

1 Engine power loss, for undetermined reasons.

2 Unsuitable terrain for a forced landing.

The pilot had planned to fly an aircraft equipped with fixed landing gear. However, the keys for this aircraft could not be found so he flew another aircraft of the same type, but which had retractable landing gear. On arrival at the destination aerodrome, the pilot forgot to lower the landing gear and landed with the gear retracted.

The pilot of VH-WZB had completed an IFR training session at Tailem Bend and departed for Adelaide, maintaining 4,000 feet and flying in and out of cloud. He was advised by Adelaide Flight Service of opposite direction IFR traffic, VH-NIQ, enroute from Adelaide to Tailem Bend to conduct IFR training and maintaining 5,000 feet.

A short time later an electronic traffic alerting system installed in VH-WZB alerted the pilot of an aircraft approaching head-on at the same level. The instructor descended the aircraft rapidly to 3,500 feet and the traffic, which was identified as VH-NIQ, passed overhead.

The Flight Service Officer had overlooked amended details concerning VH-NIQ revising its cruising altitude to 4,000 feet.

The pilot noticed an abnormal noise as the landing gear retracted following take-off from Bathurst Island. After selecting the gear down in the circuit area at Snake Bay he noticed that all three gear down lights were illuminated.

A normal circuit and landing was carried out, but during the landing roll as the nosewheel contacted the runway it collapsed rearwards, allowing the underside of the nose and both propellers to contact the runway.

Subsequent investigation revealed that the nose gear retract actuating rod had failed at the drag brace rod-end fitting. Because of the location of this failure the gear down microswitches were still actuated, giving the pilot a false gear down and locked indication.

After landing the helicopter in a confined area the pilot had some reservations about its ability to climb over adjacent trees. He identified an area that appeared suitable for a run-on landing in the event of the need to reject the take-off.

After commencing the take-off, the pilot realised that there was insufficient power available to clear the trees and manoeuvred the helicopter for a run-on landing in the area he had previously identified.

During the ground run, just before the helicopter came to a stop, the ground gave way into an underground cavity. The helicopter pitched forward, and the main rotor struck the ground.

Air traffic control (ATC) cleared the pilot of VH-EWF to descend to 5,000 ft and to divert left of the 144 VOR radial as required to avoid weather. However, the pilot subsequently diverted to the right of the 144 radial. A breakdown in separation standards occurred with VH-XFT, a scheduled passenger flight outbound from Rockhampton, on climb to 7,000 ft and tracking via the 116 VOR radial.

The pilot of VH-EWF had requested clearance to track 5 NM left of the 144 radial. He was advised by ATC that the clearest conditions were to the west of that radial. The pilot later advised that he had diverted 5 NM left (west) of track. However, he had subsequently diverted to the right of the 144 VOR radial, and at 15 NM from the aerodrome, the aircraft was established on the 125 VOR radial.

The aircraft was engaged in parachute-jumping operations which involved free-fall jumps from 10,000 ft. Five parachutists were carried on each flight. The aircraft had operated normally during earlier flights that day and the pre-take-off engine run-up revealed no abnormalities.

The pilot reported that as the aircraft approached 300 ft and he was about to make the first power reduction shortly after take-off, there was a momentary power fluctuation. He decided to turn back towards the runway but during the turn the engine started to miss significantly and lose power to the extent the aircraft could not maintain height. The engine failed to respond to the normal trouble-checks which included switching the electric fuel pump on.

As the aircraft descended through 100 ft it was apparent that the engine was producing no power. The pilot extended full flap when he heard the aural stall warning and subsequently commenced the landing flare too early and had to lower the nose before attempting a second flare for the landing. The aircraft impacted heavily and almost immediately rolled over onto its back.  The five parachutists, who were unrestrained, were injured in the accident and the pilot received minor injuries when his seat detached from the floor rails.

The loss of engine power was the result of an excessively rich fuel/air mixture. Investigation revealed rubber deposits jammed under the variable adjustment needle in the engine-driven fuel pump, blocking the return port. This resulted in an oversupply of fuel to the metering unit and an excessively rich fuel/air mixture. The rubber had originated from the internal lining of the fuel hoses between the pump and the metering unit. The fuel/air mixture was further enriched when the pilot switched on the electric fuel pump, resulting in the complete loss of engine power.

Distracted with troubleshooting the engine problem, the pilot allowed the airspeed to decay to the point where the stall warning activated. The airspeed decreased further during the initial flare and a high sink rate developed which the pilot was unable to correct, resulting in the heavy touchdown. The nose gear leg failed in overload and the aircraft nosed over onto its back.

Investigation of the pilot's seat revealed it had been repaired some time prior to the accident. The repair differed from the original design and compromised the lock function. During the accident sequence, the lock withdrew and the two unrestrained parachutists who were located behind the seat moved forward and pushed the seat out of the tracks. Single-point restraint lines were fitted for use by the parachutists, but they had not been used.

Significant factors

The following factors were determined to have contributed to the accident.

1. Rubber debris had detached from the internal lining of engine fuel hoses, contaminating the engine-driven fuel pump and resulting in an excessive fuel supply to the engine with subsequent loss of power.
2. Activation of the electric pump in accordance with the flight manual procedure resulted in an oversupply of fuel to the engine with a complete loss of power.
3. The airspeed decayed sufficiently to preclude a safe forced landing.

SAFETY ACTION

As a result of the investigation, interim recommendation IR950014 was issued to the Civil Aviation Authority on 16 February 1995.  It stated:

The Bureau of Air Safety Investigation recommends that the Civil Aviation Authority and the Australian Parachute Federation evaluate the adequacy of current legislation with regard to restraints for parachutists in aircraft.

The Civil Aviation Authority response to this recommendation dated 27 April 1995 stated:

I refer to BASI Interim Recommendation IR950014 regarding an accident involving parachute operations at Nowra.

The report notes that no restraints were being worn by the occupants of the aircraft and opines that their injuries would have been more severe had the single-point restraints (which were fitted to the aircraft) been used.

In 1991 the Authority conducted a study in response to a request from the Australian Parachute Federation (APF) to delete the requirement to wear any restraint on take-off, landing and below 1000 ft. CAO 20.16.3 permits the use of approved single-point restraints for parachutists in lieu of the normal seat belts or safety harness. The APF expressed some concerns about the possibility of a restraint snagging a parachute and causing premature opening. The Federation was also of the view that the use of single-point restraints could cause more injuries than not using them.

The Authority concluded that the advantages and disadvantages of single-point restraints were fairly evenly balanced.  However, at about this time a fatal crash occurred to an Army Pilatus Porter aircraft, where the main cause of injuries and deaths was unrestrained bodies flailing around the cabin.  Also, several accidents occurred in the USA to larger aircraft in parachuting operations, which were attributed to loss of control following movement of the centre of gravity.  As a result of these accidents, it was decided to confirm the requirement for some form of restraint. The APF at the time indicated that they preferred the single-point restraint option over a full seatbelt or safety harness.

Notwithstanding, our earlier study of this requirement, it is agreed that this issue needs further examination. A review will be carried out in conjunction with the APF.

Response status: Closed-accepted

The Bureau of Air Safety Investigation intends producing an article for inclusion in a future edition of the Asia-Pacific Air Safety magazine concerning the problems associated with non-standard aircraft repairs.