The pilot of VH-LGI, enroute from Maningrida to Darwin, reported to Adelaide Flight Service that he had experienced a breakdown in separation with an aircraft travelling in the opposite direction.

He was advised there was no other instrument flight rules traffic in the area, and that the aircraft was VH-AMQ operating under the visual flight rules on a SARTIME flight, and therefore not given as traffic.

Although both aircraft had made all necessary radio calls, the conflict occurred at a Flight Information Service area boundary when opposite direction traffic are monitoring different VHF radio frequencies.

The instructor and student were conducting crosswind training circuits on runway 07 at Redcliffe. At approximately 200 ft AGL after take-off on the third circuit, the engine began to run very roughly. The instructor immediately assumed control and transmitted a Mayday call. A decision was then taken to carry out a landing, onto the clear swampy terrain, straight ahead. The aircraft nosed over soon after touching down onto the soft surface. Both occupants were able to exit the aircraft without assistance.

The investigation found that the number 4 engine cylinder had a large fatigue crack in the non-finned base area, that extended approximately two thirds the circumference of the cylinder wall. No other defect was found with the engine, accessories or engine control systems that would have contributed to the rough running.

It is probable that the rough running was caused by excessive valve clearances and/or piston to cylinder binding, as the crack opened under load.

Factual information

VH-MZI departed Albury at 1634 EST on a flight to Canberra. The aircraft was maintaining 9,000ft and the pilot contacted Canberra approach control (APP) prior to the control area (CTA) boundary for an airways clearance, advising that he was on the 238 degree radial of the Canberra VOR. This was north of the nominated track (the 234 degree radial) and was due to conflicting traffic outside controlled airspace. The fact that VH-MZI had reported north of the nominated track was not assimilated by the approach controller.

Canberra Approach and Departures control were being operated in the combined mode at the time of the incident due to the low volume of air traffic. The controller performing both functions was positioned at the approach console and had set the approach radar display on the 40 NM range and the departure control console radar display on the 80 NM range. He issued an airways clearance for VH-MZI to enter control area on track direct to Canberra at 9,000ft and identified the aircraft on the radar display at approximately 50-55 NM from Canberra. This identification was made on the departure control radar but, with the 80 NM range selected, the display did not readily indicate that VH-MZI was offset four degrees from the nominal track.

VH-ARQ departed Canberra for Albury at 1656 and had been processed by APP to intercept the flight planned route (234 radial) on climb to 8,000ft.

At 1704, the pilot of VH-MZI requested descent for his arrival at Canberra and was cleared to descend to 4,000ft, maintaining terrain clearance by visual reference to the ground. At the same time, the controller issued VH-MZI a radar vector right to heading 090 degrees with the intent of ensuring radar separation between VH-MZI and VH-ARQ. The controller had still not noticed that VH-MZI was north of the nominal track. Consequently, the vector on to heading 090 turned that aircraft across the flight path of VH-ARQ instead of resolving the 'nose to nose' confliction.

At 1704.40 the pilot of VH-ARQ reported level at 8,000ft. At approximately 1705, the controller checked his 40NM range radar screen and realised that the radar separation between VH-MZI and VH-ARQ was nearing the minimum of 5 NM.

At 1705.50, in response to a request from the approach controller, the pilot of VH-MZI reported his altitude as 8,300 ft. Seven seconds later, the approach controller asked the pilot of VH-ARQ to sight VH-MZI passing five miles ahead of him. The pilot reported that he had the other aircraft in sight and later said that he thought the distance was nearer to two miles than five. The pilot of VH-MZI also sighted VH-ARQ at approximately the same time and also thought the distance to be approximately two miles.  Both pilots commenced avoiding action at this time by turning right.

Radar analysis showed that the aircraft passed within 800m at the same level and with a closing speed in excess of 300 knots. This occurred at 1706.16, eight seconds after the controller had initiated the request for the pilot to maintain his own separation. The required separation standard was 5 NM horizontally by radar, or 1,000ft vertically. An instruction to a pilot to sight traffic and maintain separation visually is a valid option for a controller but it must be exercised in sufficient time to enable the pilot to position his aircraft relative to the traffic.

Controllers on duty at the time of the occurrence considered the radar display to be of poor quality. They stated that it was "blurry", "fuzzy” and "swimming" during the period surrounding the occurrence. The display was suitable for separation purposes but did not allow ready differentiation between an aircraft on-track and an aircraft a few degrees off-track.

Significant factors

1. The radar display was such that small track deviations were not readily discernible on the 80 NM range scale.
2. The approach/departures controller did not assimilate the fact that the pilot of VH-MZI reported on the 238 degree radial of the Canberra VOR in lieu of the expected track of the 234 degree radial.
3. The radar vector given to VH-MZI turned that aircraft across the flight path of the other aircraft.

The student helicopter pilot elected to conduct an unsupervised hover practice at Casey Airfield.  His total helicopter experience was 27 hours dual and seven hours solo, all in his privately owned Rotorway EXEC 90.  The terrain over which the helicopter was hovering was level ground covered by grass about half a metre high.  The wind was calm and visibility excellent.  The pilot advised that while trying to land, the front of the right skid touched the ground first and the helicopter rolled over onto its side.  Damage sustained by the helicopter was consistent with a rollover accident.  The rollover probably occurred as the helicopter drifted sideways with the landing skids in the grass.

During wreckage inspection of VH-COC it was discovered that the collective scissor link block was off its mount and that the nuts had been pulled off the two 3/16 bolts which attach the block to its mount.  There was concern that had the block pulled free before impact, loss of collective control would have occurred, probably resulting in sudden flat pitch on both main rotor blades.  Such loss of control in the hover probably would have caused the helicopter to be slammed onto the ground with more resultant damage than occurred in this rollover accident.

Another wrecked Rotorway EXEC 90, VH-YCP, was examined for comparison. Its scissor link block was still attached but score marks and fretting under the bolt heads were evidence that the block had not been securely attached to the airframe mount.  Similar evidence of fretting was subsequently found on VH-COC.  On both helicopters the airframe mounts were not flat surfaces. Also, both mounts were coated with paint which could be detrimental to a close tolerance fit.  In contrast, the base of the scissor link block was a machined flat surface.  When one end of the block was attached with a bolt, the other end of the block was proud of the steel mounting plate by 0.020 inches.

It was discovered that the Civil Aviation Authority (CAA) had required the collective scissor link attachment bracket, originally supplied by the manufacturer, to be replaced by the block of aluminium.  A bracket might flex enough during installation to achieve a flush fit with the mounting plate, whereas the aluminium block was inflexible.

Further inspection of Rotorway helicopters discovered that there was no airframe down stop for the collective lever in the cockpit and that the mechanical advantage between the collective lever and the scissor link was 24 to 1. Pushing down on the collective lever placed the two 3/16 bolts in tension.  Several 3/16 aircraft bolts were tested in tension to destruction. On average the nuts pulled off the bolts at 2714 ft/lbs.  In training, particularly during practise autorotations, it is normal for the pilot (occasionally for both the pilot under instruction plus the instructor) to push down on the collective to ensure flat pitch.  The combination of bolts under tension and the non flush fit of the blocks on VH-COC and VH-YCP had caused the blocks to move/work in the past and in time could have caused the bolts to fail.

Significant Factors

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

1. The student pilot conducted an unauthorised solo flight.
2. The pilot probably inadvertently allowed the landing skids to drag through long grass as the helicopter drifted sideways in the hover.

Safety Action

The CAA was immediately informed of the Bureau's findings and concern about the attachment of the collective scissor link block to the airframe.  A CAA Airworthiness Surveyor inspected VH-YCP. The Australian agent for the Rotorway kit helicopter was advised verbally of the findings.  The CAA approved Australian Rotorway EXEC 90 test pilot, and the CAA test pilot were advised of the findings as soon as possible.

Since this accident there has been a Rotorway EXEC 90 incident in which cyclic control became marginal in flight, resulting in a very unsafe condition. This incident exposed that the aircraft type did not comply with the flight characteristics requirements for an amateur built helicopter in Australia.  It was found that the friction and adjustment of the slider ball (uniball) was temperature sensitive and had caused binding of the cyclic control system. The instructions provided by the manufacturer to address cyclic binding were not acceptable to the CAA.

The CAA was not made aware of the potential cyclic problem during the application for the amateur built aircraft approval process.  Accordingly, the CAA has withdrawn Permits to Fly, and a Certificate of Airworthiness will not be issued for any helicopter of this type until the matter of the cyclic control is resolved.

The pilot landed the helicopter in an open grassy area to refuel from jerry cans.

He then decided to reposition the helicopter about 10 metres forward from the original landing point, and after the passenger alighted lifted the helicopter into the air and applied forward cyclic. It suddenly pitched forward sharply as if the front of the skids were caught, the main rotor blades striking the ground before the pilot could regain control.

The landing area was covered with medium height stiff grass that may have fouled the skids as the helicopter became airborne.

The pilot of VH-OWK was on a solo navigation training flight. A clearance was requested from Wagga Tower to enter the Wagga control area step. Due to other traffic the pilot was told to remain outside the control area and to expect a delay.

Subsequently the pilot gave a position report that showed the aircraft was in the control area and conflicting with an F27 aircraft, VH-FNC. Instructions were given to the pilot to make a 180 degree turn and radar separation was established. The pilot then elected to return to Canberra without completing the planned flight.

Significant Factors

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

1 Pilot of VH-OWK inexperienced.

2 Poor navigation, by pilot of VH-OWK.

The pilot reported that there was no indication of a malfunction when the landing gear was retracted, after take-off from Mt Isa. The flight was uneventful, and the landing gear indications (three green) were normal when the gear was selected down, in the circuit at Birdsville. The gear indications were rechecked and confirmed again on final.

Touchdown on the main landing gear was normal, but as the nose wheel tyre contacted the runway the nose landing gear collapsed. The aircraft then slid to a halt on the edge of the sealed runway left of the centreline.

All four persons on board were able to exit the aircraft safely.

The investigation found that the cage surrounding the rod end ball of the nose gear actuator rod had broken. This then allowed the actuator to disconnect from the drag brace assembly, which caused the nose landing gear to collapse, as the landing loads were applied.

The number 1 engine was shut due to an indication of increasing vibration. The aircraft diverted to Melbourne where investigation disclosed that the increasing vibration reading was caused by a chafed wiring harness. The harness had chafed due to a poorly positioned support clip allowing contact between the harness and the fan case.

The instructor pilot reported that the landing approach appeared normal but was a little fast. The initial touchdown was normal, but the aircraft ballooned then touched down on the nosewheel which collapsed.

The instructor commented that the student pilot may have been hurrying his circuit to avoid any delay to two military helicopters that were entering the circuit. In doing so, the student pilot conducted the approach at a higher-than-normal airspeed and then attempted to force the aircraft onto the runway.

VH-WMJ was tracking from 18 miles south-east of Wagga direct to Young, descending from 8000 ft to 7000 ft. A RAAF DC3, Tester 922, was tracking from over Wee Jasper to over Wagga at 8000 ft. The crew of Tester 922 called Wagga Tower at 33 miles requesting clearance to enter the control area. This position was 2 miles inside the control area and a clearance to enter had not been previously requested or given.

Although the aircraft were well clear of each other the separation standards were infringed.

Significant factors

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

1. The crew of Tester 922 did not follow required procedures and obtain a clearance prior to entry into controlled airspace.