The helicopter was conducting a scenic flight at Kings Canyon when the engine began to run rough and lose power. The pilot lowered the collective pitch lever, opened the throttle and turned towards lower terrain. The engine would not deliver sufficient power to sustain level flight, so the pilot commenced an approach to an adjacent helipad. During the landing the tail stinger and tail rotor struck the ground.

An examination of the engine revealed a spark plug malfunction and an intermittently sticking exhaust valve in the number 4 cylinder, and the pushrod ball end in the number 1 cylinder was also found to be loose, preventing the exhaust valve from fully opening.

The power loss from these engine faults, combined with the high-density altitude and weight of the helicopter at the time of the occurrence left the pilot with little option than to make a low powered, semi-autorotational landing as soon as possible.

An unidentified aircraft, later identified as VH-JEB, was observed inside the Melbourne control zone in the Sunbury area on a south-south-easterly heading. The mode C readout showed the aircraft was at 1900 feet. At the same time, VH-CZU was becoming airborne from runway 27 on an "Avoca one" departure. VH-CZU was instructed to maintain runway heading and asked to look for the other aircraft. The crew of VH-CZU sighted VH-JEB and passed two miles in front of it and 200 feet higher.

The pilot of VH-JEB reported that he had become distracted after initiating a diversion back to Essendon due to concern about fuel reserves. He was conducting a solo navigation training exercise.

The pilot had planned to carry out a short cross-country flight from Wedderburn via Goulburn, Taralga and Mittagong before returning to Wedderburn. He said that he had owned the aircraft for about eight years and was very familiar with its operation. On the morning of the flight, he measured the fuel contents of the left and right fuel tanks using a wooden dipstick and found that each tank contained 92 litres of AVGAS. From his experience, the normal fuel consumption was 37 litres/hr.

The flight to Taralga was uneventful in clear but turbulent weather conditions. However, as the aircraft tracked towards Mittagong the engine suddenly lost complete power. About one minute earlier the pilot said he had detected a slight amount of rough running and had used carburettor heat for about 30 seconds, without any change being noticed. When the engine lost power he was at a height of about 1500 feet above ground level. Despite changing fuel tanks, and turning the fuel boost pump on, power was unable to be restored. Due to limited height the pilot had to attempt a forced landing onto a steeply sloping field with rocky outcrops. Shortly after touching down the landing gear struck an outcrop and was torn off, stopping the aircraft from continuing into a valley. Both the pilot and his passenger were unharmed.

Although the total flight time had been about 61 minutes the left fuel tank was subsequently found to have been empty at the time of the accident. The engine was later able to be started and run. The pilot was unable to account for the apparent loss of fuel.

The pilot was spraying a paddock that he had sprayed three weeks previously. As some light rain was approaching, the pilot restricted his flight check of the paddock to one quick circuit. He did not notice the set of wires outside the spray paddock and did not remember them from the previous application.

The pilot completed the first spray run and pulled up to set himself for the second pass. Whilst pulling up, he looked back to check the spray coming from the hopper. The aircraft was approximately halfway through its pull up when contact was made with the wires.

The aircraft crashed a short distance from the wires.

The aircraft was conducting a routine passenger flight.  Shortly after take-off from runway 35, at about 200 ft, the aircraft suffered a power loss on the left engine.  The pilot carried out the engine failure emergency procedures and ascertained that the power loss was partial.  He climbed the aircraft, flew the downwind leg at about 700 ft and landed safely on runway 35 left.

Engineers discovered that the number six cylinder head had separated from its barrel.  The CAA Materials Evaluation Facility examined the cylinder head and reported that although weld repairs to the spark plug hole, the exhaust port flange and the exhaust valve seat recess were found, these were not a factor in the cylinder failure.  The nature of the fatigue cracking indicated that cracking occurred under conditions of a stress gradient in the wall of the cylinder head, with the higher stress at the inner surface of the cylinder wall.  The crack had propagated over approximately 600 to 700 engine start/stop cycles and had worked its way around almost half the cylinder circumference before the cylinder head separated.  The crack appeared on the outer surface during the last 20 cycles. This indicated that the material toughness was good.

The crack had propagated around the circumference of the cylinder head combustion chamber at the head to barrel thread connection.  The cylinder barrel hid the crack from view.  There were no marks in the area of the fatigue propagation to indicate the cylinder had leaked exhaust gasses, nor was there any blackening of the fins on the outer surface which would have enabled detection during maintenance.

The total time in service of the cylinder could not be determined but was estimated to be one overhaul life, or 2000 hours.  Time since overhaul was 628 hours.

On the 27 July 1994, approximately 28 hours before the power loss, the company carried out a 100 hourly inspection.  A compression test was performed which revealed cylinder number six to have a low reading, but not the lowest at 66/80.  Cylinder five read 60/80.   Leakage past the piston rings due to gap alignment was thought to be the reason for the low compression.

The exact initiator for the cylinder head failure was not found.  However, harsh handling of the engine could have contributed to the failure.  Not allowing the engine to warm sufficiently before applying high power or not allowing the engine to cool sufficiently before shutting down could have caused the thermal stress gradients.

Cylinder head separation was considered to be unusual for the Lycoming TIO-540 engine.  According to the BASI data base, this was the first occurrence of a cylinder head separation in more than five years.

CONCLUSIONS

Findings

1. The cylinder head failed due to a fatigue crack.
2. The location of the crack prevented its detection during visual inspections.

Significant Factors

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

1.   Harsh engine handling may have caused thermal stress resulting in the fatigue crack.

The pilot reported that the aircraft was on descent when the engine lost power. He attempted to maintain altitude but was unable to do so.

The pilot sighted what appeared to be a gravel strip of sufficient length in the middle of the mud flats he was overflying, and he decided to fly an approach for a landing on that strip.

On late final approach, the pilot observed some powerlines crossing the end of the strip. He manoeuvred to avoid the powerlines but was unable to line the aircraft up properly, again, with the strip before the touchdown. The aircraft ran off the side of the strip and the horizontal stabiliser collided with an earth bank.

The reason for the power loss was not determined.

Sequence of Events

During clearance delivery, the co-pilot noted the level on his Take-off and Landing Data card and read back the cleared level (FL150) correctly. However, the pilot-in-command (PIC) entered FL160 in the Altitude Select Indicator before engine start. The co-pilot was distracted following his recording of the clearance by his perceived need to select the assigned transponder code (the code was unusual as 0756) without delay. This occurred at the time the PIC was manipulating the Altitude Alert Indicator. The PIC was distracted by the co-pilot's involvement with the SSR code, and the selected altitude discrepancy was not noticed by either crew member.

Further distractions included a photographic session on the tarmac near the aircraft and an unannounced request by a Flying Operations Inspector (FOI) to occupy the third seat as supernumerary crew. The crew were not wearing headsets, and the cockpit noise environment was such that the FOI did not hear the cleared level or the readback.

After take-off, the crew advised the Approach/Departures Controller that the aircraft was on climb to FL160.

Although the aircraft's flight strip indicated the correct level (FL150), the controller missed this part of the message, partially due to a high workload. At the next frequency change to Arrivals, the crew again indicated that the aircraft was on climb to FL160. The Arrivals Controller also missed the incorrect level and co-ordinated FL150 in accordance with his flight strip with Townsville Control. The Cairns Arrivals Controller did not have a high workload.

When the crew contacted Townsville Control, the aircraft had levelled at FL160. The controller realised immediately that an error had occurred but gave an ongoing airways clearance at FL160 as there was no conflicting traffic.

Analysis

A breakdown in the company's Standard Operating Procedures (SOPs) concerning cross referencing the selected altitude was the prime reason the incorrect FL160 in the Altitude Select Indicator was not detected. The distractions on the flight deck may have contributed to this error.

Two separate controllers missed an important portion of operational information at the crew's first contact on their individual frequencies. The workload level of the Approach/Departures controller probably contributed to his error. However, no reason was found to explain the omission by the Arrivals controller. ATS co-ordination procedures requires the controller receiving the information to cross check the data against the aircraft's flight strip.

Factors

1. Both crew members were distracted for a short time.
2. Flight crew pre-flight check procedures were not followed.
3. The Approach/Departures controller was under a high workload.
4. ATS coordination procedures were not carried out properly by the Approach/Departures or the Arrivals controllers in that the altitude discrepancy was not detected.

On entering the circuit, the pilot attempted to cancel his sarwatch but could not contact flight service on the aircraft's VHF radio. He attempted to relay the request through another aircraft, but this was also unsuccessful. The pilot then transferred to HF radio and was able to cancel sarwatch. During this period, the pilot was also communicating with other circuit traffic. These distractions led to him forgetting to extend the landing gear and the aircraft landed wheels-up.

Two heavy, international passenger aircraft were approaching Australia from the North West. Whilst they were in airspace under the control of the Perth Sector 2 Air Traffic Controller, communication with the aircraft was being provided by a Flight Service Officer manning the Perth Flight Information Service International 1 position. The lead aircraft requested a climb and was cleared to Flight Level 310. The following aircraft also requested a climb and the Air Traffic Controller passed a clearance to the International Flight Service Officer indicating that the aircraft was cleared to Flight Level 290. Shortly after the following aircraft commenced climbing, the lead aircraft advised that the TCAS system had indicated that there was an aircraft behind and below presenting a confliction.

The Flight Service Officer had incorrectly passed a clearance to the following aircraft for a climb to Flight Level 310 instead of Flight Level 290, and the following aircraft was detected and reported by the lead aircraft. The following aircraft descended to Flight Level 290.

The Flight Service Officer had written the correct clearance on the flight strips but had passed the incorrect level to the aircraft. The officer could not explain this, however the investigation identified some preconditions which may have contributed to the occurrence

a. The incident occurred during the last five minutes of the Flight Service Officer's ten hour shift which was due to conclude at 2300 hours. The Flight Service Officer had spent the entire shift, with appropriate breaks, working on the same operating position. Normal procedure is to attempt to rotate staff through different positions.

b. The workload, which had been light earlier in the shift, peaked just prior to the incident and was heavy and complex at the time of the incident.

c. The Shift Supervisor's workload monitoring process did not detect that the Flight Service Officer's workload had become complex and heavy and that he may have been in need of assistance.

d. The Air Traffic Controller working Sector 2 did not note the incorrect clearance, given by the Flight Service Officer, although the information was available through a Flight Service monitoring facility (part of the safety net) available to and used extensively by him prior to the incident. It is probable that the Air Traffic Controller's workload had also reached a point where he was unable to provide a monitoring service.

e. A number of environmental and organisational issues were reported as having developed from the uncertainty of the continued operation of the Flight Service organisation following the Civil Aviation Authority's airspace review. Areas such as inadequate working conditions and low staff morale were reported as major issues.

Safety Action

The Civil Aviation Authority are planning to resolve rostering and supervision issues by implementing the "team" concept for staffing within Flight Service centres. They are also employing contract staff in an attempt to reduce the load on their permanent staff.

F-ODGX planned Melbourne to Sydney via Strathbogie, designated route W32, Cullerin, Bindook and Oakdale to Sydney. Due to limitations, the computer aided strip printing system (CASPS) did not recognise waypoint Oakdale in the flight plan as valid and consequently could not print the strips.

An airways data system officer (ADSO) in the Melbourne area approach control centre (AACC) amended the plan which was then re-run with errors and omissions such as speed, flight level and route.

As a consequence, the Melbourne sector 2 and 7 enroute flight progress strips then incorrectly indicated that the flight was tracking via Strathbogie, W32, waypoint Cullerin to Sydney. Coincidently, the Sydney AACC advised non receipt of plan details on F-ODGX. The flight plan forwarded was the incorrect amended version.

F-ODGX's airways clearance was to track via Strathbogie to Sydney. On departure, the clearance was amended to track direct to Cullerin. The amended clearance was accepted by the pilot because it was on the flight planned route. At 130 NM from Melbourne, the aircraft was given a Rivet 1 arrival by Melbourne Sector 2. The pilot's readback of the clearance was unintelligible. At 160 NM from Sydney the aircraft was given an instruction to enter the holding pattern at 70 NM Sydney, with the requirement to reach flight level (FL) 210 by 70 NM from Sydney. This holding pattern is published on the Standard Instrument Arrival (STAR) plates and is located on the 230 radial, 70 NM from Sydney. On the route which the pilot followed, from Cullerin to Bindook, there is no published holding pattern at 70 NM Sydney. The pilot did not query the holding instruction reference the direction of the turn or the inbound radials.

Due to Sydney arrival sector also working from incorrect flight progress strip information, the flight planning error was not detected until the arrivals radar controller observed the aircraft making a left turn towards Bindook instead of a right turn towards Rivet.

At the time of this incident, another aircraft was tracking from Wagga Wagga to Bindook at FL210. Had the arrivals controller not observed and adjusted the incorrect turn by F-ODGX, a loss of separation standards may have occurred.

The incorrect routing of F-ODGX would have been rectified at the clearance delivery stage if the correct flight plan had been presented to the controllers handling the flight.

Significant Factors

1. The CASPS waypoint data was not compatible with the current air route structure.

2. The ADSO incorrectly amended the original flight plan.

3. The Melbourne sector controller did not obtain a valid readback of the STAR clearance.

4. The pilot did not query the inconsistent holding instruction.

Safety Actions

The Civil Aviation Authority Air Traffic Services has initiated new procedures regarding the method and circumstances in which filed flight plans may be re-run through the CASPS equipment.