Whilst transiting the lane of entry outbound to Cessnock the pilot reported that the engine started to vibrate. The aircraft was turned onto a reciprocal heading to return to Hoxton Park, but the engine began to run roughly. The use of carburettor heat had no effect, and engine RPM began to decrease. The pilot elected to carry out a forced landing on a racecourse, but during the landing roll the aircraft collided with a barrier fence.

Investigation later revealed that all spark plugs were in poor condition, with heavy erosion to the centre electrodes indicating considerable operating time. Both plugs in number 1 cylinder had broken ceramics and the electrode gaps were closed. One plug in number 4 cylinder was fouled with lead. An engine run later confirmed that the inlet valves in number 3 and 4 cylinders were also sticking.

The pilot reported that when he was approaching Mount Isa at about 1220 a regular public transport jet was taxiing for departure for Brisbane. The pilot said he advised the jet crew that he would land short on runway 16 and exit via the cross strip onto the taxiway so that they would not be delayed. In his haste to land he omitted to lower the gear, and the aircraft skidded to a halt after a ground slide of about 250 metres commencing 400 metres from the threshold.

The pilot advised that the aircraft had recently had new engines fitted and the gear warning horn was activating at an excessive power setting. As an interim measure to overcome this annoyance, he had pulled the gear warning circuit breaker.

Shortly after take-off, at a height of about 250 feet above the ground, the engine lost power. The pilot applied carburettor heat which he said resulted in a brief surge of power after which all power was lost. The pilot dumped the load but while he was manoeuvring to avoid a fence the aircraft stalled and hit the ground heavily.

Subsequent investigation revealed that the engine fuel system was contaminated with water. The pilot had refuelled the aircraft from a 200-litre drum prior to take-off. Although he checked the drum for water contamination prior to refuelling and then completed a fuel drain check of the aircraft fuel tanks, he did not detect water.

Further investigation revealed that the 200-litre drum from which he refuelled had been sitting in a utility in heavy rain for a number of days and the drum bung had a faulty seal. The pilot believed there was no doubt that he had pumped water contaminated fuel into the aircraft fuel tanks which then found its way into the engine.

Factors

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

• The pilot did not detect water in the fuel when he checked the drum source prior to refuelling the aircraft tanks.
• The pilot did not detect water in the fuel when he did his fuel drain check of the aircraft tanks after the refuelling.
• The aircraft engine lost power when it ingested water contaminated fuel.
• After the engine failure, the pilot stalled the aircraft at a low height while manoeuvring to avoid a fence.

When VH-CZM was transferred to the arrivals controller, the aircraft was observed to turn left at Wonthaggi and track 298 degrees towards BAYSI instead of 320 degrees towards Plenty. The controller subsequently radar vectored VH-CZM to Plenty. There was no breakdown in separation.

By replaying the communications tape, it was discovered that at 14.04.35 EST, the sector three controller had issued the following clearance: "Charlie Zulu Mike, STAR clearance Plenty One arrival, runway 34, maintain flight level 370."

The pilot read back: "Charlie Zulu Mike BAYSI One arrival, runway 34, flight level 370."

When the pilot read back a different clearance, the controller failed to notice the pilot's error. When the aircraft turned left, the pilot genuinely thought that he had been cleared for a BAYSI one arrival.

Significant Factors

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

1. The pilot misheard the Plenty One clearance and read back BAYSI One.

2. The controller misheard the pilot's incorrect clearance read back.

The pilot reported that he had made an approach to land on runway 32. During the landing roll the pilot became concerned that the aircraft would not stop before the end of the runway, and he decided to go around for another circuit. The pilot applied power and attempted to fly the aircraft off the ground at the end of the runway. The aircraft did not climb, and the right wing collided with a three metre high tree causing the aircraft to slew around and touch down again. The right wing, engine cowl and nosewheel were also damaged as the aircraft came to a stop, still on its landing gear and pointing in the opposite direction to the landing, approximately 70 m from the end of the strip.

It is probable that the pilot flew the aircraft off the ground at too low an airspeed and the combination of the low airspeed and its associated drag prevented the aircraft from climbing clear of the obstacles.

Soon after take-off the aircraft was observed to drift to the right of the runway centreline and disappear into cloud. Subsequently the pilot broadcast a PAN call advising that the right engine had failed. The aircraft was vectored for a return to the airfield where a single engine landing was accomplished.

Maintenance checks disclosed that the engine was slow to accelerate and, that at 90% N2, the compressor stalled. A fuel control unit change and rigging check did not clear the problem; therefore, the engine was changed.

The engine has been placed into long term storage consequently the cause of the problem has yet to be established. A major defect report has been submitted to the Civil Aviation Safety Authority.

The pilot reported that he was having difficulty lowering the landing gear. He later advised that he was unable to lower the gear and that he intended conducting a wheels-up landing.

Later engineering examination found that the push pull cable, between the gear selector handle and the power pack, had broken. CASA Airworthiness at Coffs Harbour were advised the details of the occurrence and were able to recover the broken cable for further specialist examination.

FACTUAL INFORMATION

History of the flight

The aircraft had departed Bankstown for a dual instrument flight rules (IFR) training flight, including aerial work at Goulburn followed by two practice instrument landing system (ILS) approaches at Canberra, before returning to Bankstown.

After completion of the second ILS approach, the pilot was instructed to carry out a missed approach and climb to 7,000 ft.

As the aircraft was levelling in instrument meteorological conditions (IMC), the instructor noticed that engine Manifold Absolute Pressure (MAP) had reduced from 30 inches to 25 inches. He asked the pilot if he had adjusted the power and the pilot replied in the negative. At 1127 EST, the instructor advised Canberra Approach (APP) that the aircraft had experienced a loss of power. He reported that the aircraft was able to maintain 7,000 ft and confirmed that he wished to return to Canberra for landing. Air Traffic Control then instructed the pilot to turn the aircraft onto a southerly heading.

Between 10 and 15 seconds later, the aircraft occupants heard a loud thump that shook the aircraft, and the engine RPM reduced significantly. At 1128 the pilot advised APP that the engine had failed and requested that APP provide headings to the vicinity of Lake George. APP identified the aircraft on radar at a position 17 NM to the north-east of Canberra over the western shores of Lake George. APP then passed information to the pilot about an airfield near Bungendore as a possible landing area.

At 1129, the pilot advised that assistance was still required and confirmed that the aircraft was still in IMC. APP advised the pilot to disregard the previous vectoring instructions, indicated that a landing on the Federal Highway might be possible and instructed the pilot to turn onto a heading of 020 degrees. At 1131, the pilot advised that the aircraft was descending through 4,200 ft.

At 1132, APP requested that the pilot activate his emergency locator transmitter (ELT). The pilot then advised that the aircraft was still in IMC and passing 3,500 ft. APP advised that the aircraft was passing over the northern shores of Lake George and requested the pilot to turn the aircraft right to an easterly heading to avoid high terrain in the area. No reply was received.

Another aircraft, VH-DUP, was in the Goulburn area at this time and the pilot offered to relay a message to VH-SMA. APP requested the pilot of VH-DUP to listen out on 121.5 MHz to determine if an ELT had been activated. The pilot of VH-DUP advised that he was unable to make contact with VH-SMA and confirmed an ELT signal on 121.5 MHz.

The time of the accident was 1133. A rear-seat occupant, who was also a qualified pilot, later stated that he estimated that the aircraft broke through the cloud base below 300 ft above ground level (AGL).

An army helicopter was dispatched from Canberra at approximately 1155 and proceeded to the area of the last known position of VH-SMA. A second helicopter carrying a medical team was dispatched to the area at 1230.

At 1240, one survivor from the aircraft was located by a search helicopter. Two other survivors were located soon after. All three had suffered severe burns.

Wreckage examination

Wreckage was distributed along a 49 m trail aligned approximately east. The aircraft had entered the timbered area on this track and had partially broken up as it descended through the trees. As the aircraft penetrated the timber, it struck and severed tree branches and trunks over 150 mm in diameter, starting 49.3 m and ending 28.5 m from the main wreckage, before coming to rest on a south-westerly heading against the trunk of a large tree approximately 1 m in diameter.

The main wreckage consisted of the fuselage, the fin, the right horizontal tailplane and most of both wings. The left horizontal tailplane had been torn off during the impact sequence. The empennage showed evidence of oil streaking, indicative of engine oil loss in flight. The fuselage had been almost completely destroyed by post-impact fire. The engine and propeller remained attached to the fuselage. Inspection of the propeller indicated that the engine was not producing power at impact.

The engine was basically intact and unaffected by fire. Both magnetos had separated from the engine. There were two holes in the top of the crankcase aligned with cylinders number 2 and 3. When the engine was turned over for examination, approximately 1 L of oil flowed out of the holes in the crankcase.

Pilot information

The aircraft owner occupied the left control seat. He held a valid private pilot (aeroplane) licence, issued on 1 July 1976, with PERPETUAL status. He had about 1,000 hours total experience, of which almost 600 hours were in VH-SMA. He had held a command instrument rating (single engine), issued 7 December 1987 and expired 31 January 1994, and was practising for renewal of the rating. His medical category was valid to 18 June 1996.

The right control seat was occupied by an instructor who held an air transport pilot licence, issued 1 September 1992 and with PERPETUAL status. He held a Command Instrument Rating issued 28 March 1983 and valid to 30 September 1995. He had almost 14,000 hours total experience of which approximately 3,000 hours were on Cessna 210 aircraft and more than 2,000 hours were in VH-SMA. He had held chief flying instructor and chief pilot approvals since 24 April 1990. His medical category was valid to 12 October 1995.

Weather

An intense low-pressure system was centred at 45 degrees south, 133 degrees east. This system was coupled with a low-pressure system in the Tasman Sea and a series of cold fronts were embedded in the strong south-westerly airstream associated with these systems.

The Bureau of Meteorology estimated conditions in the Lake George area as:

Wind 330/08

Visibility Less than 1,000 m

Weather Drizzle and rain throughout the area

Cloud Broken stratus, base ground level

Overcast nimbostratus, base 1,000 ft AGL

Freezing level 6,000 ft

Icing Moderate in cloud above freezing level

Surface temperature 8 degrees C

Dew point 8 degrees C

QNH 992 hPa

Upper winds 3,000 ft 310/15

5,000 ft 310/25

7,000 ft 310/30

10,000 ft 270/35

Detailed engine inspection

The engine was removed from the wreckage for detailed inspection. The engine was completely disassembled by Bureau engineers in the presence of representatives from the engine manufacturer and the Civil Aviation Safety Authority. The most significant findings were:

(a) less than 1 L of oil remained in the engine;

(b) numbers 2 and 3 connecting rods had failed;

(c) numbers 2 and 3 big end shell bearings plus their associated column supports, were severely damaged;

(d) there was significant fretting on the number 2 main bearing column support mating surface to a depth of at least 0.002 inches;

(e) minor fretting damage was present on the other column supports;

(f) one connecting rod big end bearing housing bolt had failed earlier than the rest;

(g) the torques on some cylinder retaining nuts were well below the expected values;

(h) a number of the through bolts showed evidence of fretting at the crankcase split line location;

(i) the turbocharger oil reservoir return line was broken;

(j) there appeared to be no blockage of the main oil galleries;

(k) the oil pump appeared to be working at the time of impact;

(l) the turbocharger had received no discernible damage; and

(m) there was no evidence of the typical sludging of the engine following the use of Mobil AV-1 synthetic oil.

The damage to the engine was consistent with oil starvation. The damaged turbocharger oil reservoir was considered as a possible source of oil loss and was examined in a metallurgical laboratory. The examination revealed that, in the past, the welded joint between the outlet fitting and the top cover had cracked and had been repaired by welding. Inside the lower cap were marks matching the position and shape of the outlet pipe; these marks were consistent with the outlet pipe being jammed downwards and rearwards during the impact sequence.

Maintenance history and documentation

The engine logbook showed that in August 1987, the engine had undergone a bulk strip to inspect the crankshaft and crankcase for cracks following a propeller strike. The inspection found the components to be satisfactory and the engine was returned to service. The logbook indicated that this was the last occasion on which the crankcase had been split.

The aircraft was operating with a valid maintenance release (Maintenance Release 209476, dated 4 August 1994). No daily inspections had been written up since 23 April 1995. At the last major servicing the aircraft had flown 2,400 hours and had flown a further 93.3 hours to the last entry on the maintenance release.

Air traffic control

The Canberra Approach controller later stated that the aircraft was to the west of Lake George when the pilot reported the initial engine problem. As the pilot initially stated that he could maintain altitude, the controller vectored the aircraft onto a southerly heading for a return to Canberra.

By the time that the pilot reported the engine failure, a second controller, who was very familiar with the Canberra area, was standing by. The second controller suggested the possibility of a landing on the Federal Highway to the north-east of Lake George. The approach controller then vectored the aircraft onto a northerly heading, but soon concluded that the aircraft would not reach the highway and that it was approaching an area of high terrain. He then turned the aircraft onto an easterly heading to have it fly parallel to the foreshore, where the terrain was lower and, he believed, the weather clearer.

The controller stated that he believed that there was high terrain in the vicinity of the proposed landing site near Bungendore and decided to discontinue his initial plan to vector the aircraft to that area.

ANALYSIS

The accident was the result of an engine failure in weather conditions that precluded a visual forced landing. The cloud break below an estimated 300 ft AGL, in poor visibility and over timbered terrain, denied the pilot any effective choice of landing sites.

Detailed examination of the engine established that it failed due to a loss of effective lubrication. The Bureau's technical investigators reviewed the findings from the engine examination with specialists from the engine manufacturer and the Civil Aviation Safety Authority. The condition of, and damage to the engine and other powerplant components pointed to some possible sources of loss of effective lubrication:

(a) failure of the return line to the turbocharger reservoir, causing oil loss and subsequent oil starvation to the engine;

(b) fretting of the crankcase mating surfaces and through-bolts, indicating lack of sufficient pre-load on the crankshaft bearings, and consequently allowing the bearing(s) to rotate, blocking the supply of oil to key areas in the engine; or

(c) a combination of the above.

The exact cause of the loss of effective lubrication could not be established.

Air traffic control

Had the engine failure occurred in visual meteorological conditions (VMC), the pilot would have had more options available for him to have carried out a safe forced landing in the Lake George area. However, the engine failure in IMC meant that the crew was totally dependent upon the Canberra Approach radar controller for positioning. The cloud was estimated to include broken stratus to ground level with an overcast of nimbostratus from 1,000 ft AGL, with drizzle and rain throughout the area. The controller would therefore have been required to vector the aircraft almost to touchdown to be of practical assistance in the final stages of flight.

Although he received advice from another controller who was familiar with the Canberra area, the approach controller was not so familiar. The limitations of the radar display, which depicted Lake George only in general terms (vector lines), prevented the controller from being certain of the aircraft's position with respect to terrain features. As the aircraft descended in IMC, the controller's range of options diminished rapidly and he finally concentrated upon positioning the aircraft as far as possible from known high terrain.

SIGNIFICANT FACTORS

1. The engine failed due to a loss of effective lubrication. The reason for the loss could not be established beyond doubt.

2. The engine failure occurred in weather conditions that did not permit the pilot to carry out a visual forced landing onto favourable terrain.

3. The approach controller was unable to vector the aircraft to an obstruction-free landing site due to equipment and time limitations.

When the pilot lowered the landing gear the indications were that the left main gear had not extended. After several attempts at freeing the gear by recycling, the pilot decided to return to Horn Island where a ground inspection by maintenance staff was available together with emergency services. He also ascertained that the gear bulb was serviceable.

After a fly past, it was decided that the gear appeared to be down. The hydraulic system had pressurised which indicated to the pilot that the gear was most likely locked down. The pilot decided to land. On late final approach he feathered both propellers and made all switches safe. During the landing roll the left main gear collapsed rearwards to the trailing edge of the wing but the wheel continued to rotate. The wing of the aircraft did not touch the ground. All persons on board evacuated the aircraft safely.

Post flight inspection revealed that the centre drag bolt had sheared allowing the left gear to fold rearwards.

Evidence from the major defect report indicates that the bolt had failed as a result of being overstressed on a previous occasion probably as a result of an unreported heavy landing.

On left base for runway 26 at Essendon the right engine started to run roughly and surge and continued to do so until the aircraft landed. Towards the end of the landing roll the right engine stopped. The pilot reported that after the aircraft was parked the fuel gauges were indicating 200 lbs per side. When inspected, the right fuel tank was found to be empty. The right engine subsequently ran normally during a ground run with the left tank selected.

The aircraft was delivered to its maintenance organisation where it was determined that the indicating system for the left fuel tank was faulty. A signal condition unit was replaced and a fuel calibration carried out after which the aircraft was returned to service.

Investigation of the operational factors revealed that it is the operator's standard practice to fill the tanks to a total of 1250 lbs of fuel for a typical day's operation. It is not possible to see the fuel through the filler point when the tanks are only filled to this level. It is therefore normal practice to cross check fuel added against calculated fuel used on the previous flight and gauge indication as a check of fuel in the tanks.

On the flight that terminated in this incident, the pilot had crossfed fuel in flight from the right tank due to unbalanced gauge indications. Hence, the reason that the right tank ran dry while there was still plenty of fuel in the left tank.

Factors

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

• The fuel quantity gauge indication for the right tank was inaccurate due to a faulty signal condition unit.
• The inaccurate indication for the right tank led the pilot to believe that there was an imbalance between the left and right tanks.
• Because of this perceived imbalance he crossfed from the right tank during flight until the imbalance appeared to be corrected.
• This in turn resulted low fuel quantity in the right tank which eventually led to the right engine being starved of fuel.