Forced/precautionary landing

While cruising at 3000 ft, the engine suddenly lost power to the extent that level flight was no longer possible. The pilot conducted a forced landing on to a rough field, causing damage to the landing gear, fuselage, and propeller. Investigation revealed a failure in the rocker gear of the number four exhaust valve.

The pilot reported that while flying at 350 feet above ground level, maintaining 50 knots, the engine started to vibrate violently and lose power until it stopped. Prior to the power loss, all temperatures and pressures were normal. The pilot entered autorotation but due to the unsuitable terrain he had to make a very steep descent to put the aircraft onto a suitable landing site. In doing this, he made a heavy touchdown which resulted in a main rotor blade striking the tail boom causing substantial damage.

The engine failure was later determined to have been caused by failure of the number two connecting rod assembly. The failure of the assembly was caused by fatigue crack growth in the connecting rod cap. The factors that contributed to the fatigue crack initiation were not determined.

The aircraft was being ferried to the Philippines. An intermediate stop was made at Palau, where it remained idle for about a month. The pilot reported that prior to take-off from Palau he had refuelled the aircraft from drum stock and that subsequent water drain checks were clear. Pre-take-off checks were normal but during take-off, as the aircraft was rotated at about 90 kts, the right engine lost power. The pilot said he feathered the propeller, and retracted the flaps and landing gear, but the aircraft failed to achieve single engine climb speed. Because the left engine oil temperature was at the red line the pilot elected to carry out a wheels up forced landing onto a sandbar on an adjacent island.

Photographs of the damaged aircraft indicated the right propeller blades were not in the feathered position. The propeller did not appear to have been rotating at impact. The reason for the loss of power was not determined.

The aircraft was cruising at 4,500 feet when the engine stopped without warning. The pilot landed in a partially cleared paddock, the only suitable area. During the landing roll the aircraft struck trees, and the nose gear was torn out. The aircraft nosed over, coming to rest inverted.

Failure of the magneto drive gear caused the engine failure. Investigation found the detached gear in the engine oil sump. The aircraft had suffered a recent propeller strike (130 hours prior) and it appeared that the gear had been defective for some time. The fracture face was discoloured from carbon/oil deposits. It is possible that the two events were related.

On 28 March 2014, the aircraft departed Numbulwar, Northern Territory on climb to a planned cruising altitude of 4,500 ft above mean sea level (AMSL). When about 22 NM west of Numbulwar, the passenger felt a bump and detected smoke emanating from the floor area beside the pilot. The pilot broadcast a ‘MAYDAY’ call on the common traffic advisory frequency (CTAF) advising of an engine failure and also that there were no roads in sight on which to conduct a forced landing, only trees.

The pilot of HGZ then asked the passenger to retrieve the fire extinguisher, which the passenger passed to the pilot. The passenger reported that the smoke stopped very quickly. The aircraft descended and the pilot retrieved the portable emergency locator transmitter (ELT) from the front compartment, extended the antenna and activated it. The pilot advised the passenger to brace for landing.

The passenger reported that the aircraft landed heavily, skidded, and collided with two trees prior to coming to rest at an angle, but upright. The passenger quickly undid the seatbelt and exited the aircraft through the open right door, assisting the pilot out of the aircraft.

The passenger and the pilot moved about 10 m from the aircraft, prior to multiple explosions occurring. Both sustained serious injuries and the aircraft was destroyed.

An initial engineering inspection found that a broken connecting rod was the most likely cause of the engine failure.

Aviation Short Investigations Bulletin - Issue 31

The aircraft, with the pilot and three passengers on board, departed Tjuntjunjarra with fuel sufficient for the flight. The auxiliary tanks were selected after the aircraft reached a cruising altitude of 3,500 ft AMSL. The cruising altitude, which was 2,200 ft above ground level, was selected because of potentially adverse wind conditions at higher altitudes. The pilot was unsure of the precise contents of the auxiliary fuel tanks, because of an indicator inaccuracy, but he expected to gain at least a further 30 minutes endurance from them. Twenty five minutes after departure the right engine lost all power.

The pilot assumed that the right auxiliary tank had run dry and he selected the right fuel selector to the main tank. The engine did not re-start and the pilot observed the fuel flow to be zero. To ensure that the left engine continued to run the pilot selected the left fuel selector to the main tank.

The pilot then attempted to select the right auxiliary fuel pump to HIGH (the settings are OFF, LOW and HIGH) but inadvertently selected the left pump to HIGH. Realising his mistake, the pilot reversed the selections. Shortly after, the left engine also lost all power.

In an attempt to rectify the situation, the pilot carried out an engine failure and re-start check on the right engine, selecting HIGH on the auxiliary fuel pump (as directed by the Engine Failure During Flight check list). He also altered the fuel selections for both engines, from main to auxiliary and back to main. At no stage did he feather either propeller. During the attempts to re-start the engines the left auxiliary fuel pump was also selected too HIGH. The only response to the pilot's actions was a momentary surge of power from the right engine.

During the trouble-shooting process the pilot had placed the aircraft in a glide descent and turned towards the nearest clear area. Within approximately 2 minutes of the first loss of power the aircraft was approaching 500 ft above ground level, and the pilot decided to concentrate his efforts on completing a successful forced landing and ceased his trouble-shooting activities. He lined the aircraft up on a clear area and attempted a landing, using full flap, with the landing gear retracted. The aircraft touched down heavily before colliding with several trees and sliding to a stop.

The occupants, all of whom received back injuries, evacuated the aircraft through the forward cabin door and the baggage compartment door.

A check of expected fuel consumption against auxiliary tank contents indicated that the right auxiliary fuel tank ran dry at about the time that it should have. Consequently, the most likely reason for the initial loss of power in the right engine was exhaustion of the fuel in the right auxiliary tank.

The Aircraft Flight Manual contains the following CAUTION.

'If the auxiliary fuel pump switches are placed in the HIGH position with the engine-driven fuel pumps operating normally, total loss of engine power may occur.'

Operation of the auxiliary fuel pump in conjunction with the engine-driven pump can cause an over-supply of fuel to the engine and an excessively rich air/fuel mixture which can lead to a power loss.

As both engine-driven fuel pumps appeared to be operating normally up until the time of the power loss, the most likely reason for the loss of power in the left engine and the failure of both engines to re-start normally was that the pilot had selected both the auxiliary fuel pump switches to HIGH during his troubleshooting. The momentary surge of power from the right engine probably occurred as the fuel pressure passed through the normal range, with HIGH selected, as it built up to a level that caused the engine to lose power again.

The pilot was aware of a cockpit placard which indicated that the auxiliary fuel pump should be selected to HIGH if there was very low or no fuel pressure. He was also aware that the engine failure checklist indicated that he could operate the auxiliary fuel pump on HIGH if the fuel pressure was deficient. His initial selection of HIGH was based on his observation of a zero-fuel pressure reading. The pilot was not aware of the CAUTION in the Aircraft Flight Manual nor of the danger of operating the auxiliary fuel pump switches on HIGH. He could not recall covering this during his endorsement training on the type. However, his instructor believed that it had been.

The aircraft should have been capable of maintaining height on one engine. The immediate priority following the right engine failure should have been to ensure continued operation of the left engine. The pilot's perception of the urgency of the situation caused him to divert his attention to the restoration of power to the right engine. As a result, his actions exacerbated the problem.

The deficiency in the pilot's knowledge concerning the use of the auxiliary fuel pump HIGH setting, and which action should have had priority, was not identified by the operator's check and training system, as the pilot was employed on a casual basis and had not been checked by the operator in the Cessna 310.

The low cruising altitude chosen by the pilot reduced the amount of time available to trouble-shoot the problem before he had to make a commitment to the landing.

Significant Factors

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

1. The pilot's preparation for flight in the Cessna 310 was inadequate, in that his knowledge of the aircraft's systems was insufficient to meet the requirements of a basic abnormal situation.

2. The operator's procedures were deficient in that they did not attempt to identify the pilot's level of system knowledge prior to allocating him to a commercial task.

3. The low cruise altitude reduced the amount of time available for the pilot to trouble-shoot the situation.

The Papua New Guinea Accident Investigation Commission (PNG AIC) is investigating a double propeller overspeed and impact with terrain, followed by a fire that occurred 33 km south-east of Madang, Madang Province, Papua New Guinea on 13 October 2011. The accident involved a Bombardier DHC-8-108 aircraft, registration P2-MCJ, with two pilots, a flight attendant, and 29 passengers on board. Twenty-eight passengers sustained fatal injuries during the accident sequence, one passenger survived with serious burns and all three crew survived.

The investigation is being carried out in accordance with Papua New Guinea's obligations as the State of Occurrence under Annex 13 to the Convention on International Civil Aviation Aircraft Accident and Incident Investigation (Annex 13). Shortly after the accident, the PNG AIC requested Australian Transport Safety Bureau (ATSB) assistance in the conduct of the investigation by providing investigator support, technical advice and facilities support.

In accordance with paragraph 5.23 of Annex 13, the ATSB appointed an accredited representative and a number of advisers to assist the PNG AIC. To facilitate this support, the ATSB commenced an external investigation under the Transport Safety Investigation Act 2003 and assisted the AIC during the on‑site phase of the investigation, in the technical examination of a number of recovered aircraft items and components, with the download and analysis of the aircraft’s flight data and cockpit voice recorders and as requested by the AIC during the remainder of its investigation.

The PNG AIC is responsible for and will administer the release of the final investigation report into this accident. Any enquiries in respect of the ongoing AIC investigation should, in the first instance, be directed to:

Mr David Inau
CEO, PNG Accident Investigation Commission

Telephone: +675 323 2911 and 323 2151
Facsimile: +675 323 2139

Email: dinau@aic.gov.pg

Address:
Accident Investigation Commission
C/- PO Box 1489
Port Moresby
National Capital District
Papua New Guinea

 

 

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Released in accordance with section 25 of the Transport Safety Investigation Act 2003.

Circumstances:

The aircraft was engaged on a navigational exercise from Bankstown to Dubbo via Bathurst and return. Due to unfavourable weather, it was decided at Bathurst to return to Bankstown. Approaching Katoomba at 4000 feet, deteriorating weather required a diversion south of track over Lake Burragorang and a descent to 3500 feet. Rich mixture was selected prior to the descent. When cruise power was reinstated at 3500 feet, the engine suffered a substantial loss of power. The instructor took control and carried out a trouble check, which included the selection of carburettor heat, but was unable to prevent a total loss of power. A glide approach was made towards the only cleared area, a road near the lake shore. During the glide, it became apparent the aircraft would not reach the road. The aircraft was ditched into the water, about 10 metres from the shore. All three occupants were able to evacuate the cabin and make their way to the shore. The reason for the engine failure could not be positively established. However, given the high relative humidity at 3500 feet and rich mixture setting, the loss of power was consistent with the effects of carburettor induction icing.

Significant Factors:

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

1. The aircraft was operating in conditions of high relative humidity.

2. The engine was operating at a rich mixture setting.

3. Complete loss of power in flight, probably due to carburettor induction icing.

4. Due to stress of weather, the aircraft was flown over terrain unsuitable for a forced landing.

This accident was not the subject of an on-scene investigation.

Circumstances:

The pilot had been spraying rice fields when the aircraft began to vibrate severely and lose height. He began a turn into wind to position the aircraft for a forced landing in a dry paddock, adjacent to the field under treatment. During the turn the aircraft struck a small earth bank which tore off the main landing gear. The reason for the vibration has not yet been established. However, a piston failure is suspected as pieces of piston and piston ring material were found in the engine sump.

Circumstances:

The aircraft was approximately 40 minutes into the flight when the pilot noticed a substantial loss of oil pressure. He initiated a diversion to the nearest suitable aerodrome, but several minutes later, following an increase in RPM, the engine failed. A small quantity of oil appeared on the windscreen and the cabin filled with smoke. The propeller continued to windmill during the descent, causing moderate to severe vibration from the rotating engine. A successful wheels-up forced landing was carried out into a cleared area. Inspection of the engine revealed a hole in the top of the crankcase adjacent to and rear of the oil filler neck which was caused by the failure of the number four connecting rod. The screws attaching the oil filler neck flange to the crankcase were found to be excessively loose, allowing a gap between the flange and the crankcase. There were no other apparent oil leaks. The aircraft had undergone a major inspection and top overhaul 108 hours prior to the accident and had flown 5 hours since the last periodic inspection. There was no reason to remove or loosen the oil filler neck at either of these inspections or during the salvage operation. Before further inspection of the engine could be carried out, it was discovered that the filler neck had been retightened. This caused metal fragments which had been suspended in the oil to become embedded into the gasket material. This confirmed that contaminated oil had exited the engine through this aperture. The pilot stated that he had checked the oil level and the security of the oil cap prior to the flight without noticing any looseness of the filler neck. The oil filler neck may have been loose during the earlier part of the accident flight but was held in position by the screw threads catching and interfering with the holes in the filler neck flange. The pilot's twisting action on the cap, as well as vibration and crankcase pressure may have caused the filler neck flange to lift off the crankcase, probably with the gap between the flange and crankcase being positioned in such a way that a capillary action was created by the airflow, causing the hot oil to be drawn from the crankcase. The oil then flowed with the cooling air between cylinders number four and five to both the underside and lower left-hand surfaces of the fuselage via the nose wheel well, all of which were thickly coated in oil. There was an insignificant amount of oil, with relatively dry carbon and sludge deposits in the crankcase breather outlet and associated plumbing, indicating that the oil had not escaped from the engine via that route. As the oil level in the engine decreased, oil pressure also decreased, and with insufficient oil flow and pressure to operate the propeller governor, normal rotational loads on the propeller moved the blades towards the fine pitch position increasing the engine RPM. Oil starvation caused overheating of the crankshaft, allowing the babbit alloy of the connecting rod bearings to melt. The number four connecting rod bearing was the first to fail, with separation of the bearing cap allowing the rod to flay about, causing the hole in the top of the crankcase. The small amount of oil thrown onto the windscreen indicated that most of the oil had already escaped from the engine prior to the failure.

Significant Factors:

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

1. The engine developed a serious oil leak.

2. The oil filler neck to crankcase attachment screws were excessively loose, probably allowing oil to escape from the engine through the gap between the oil filler neck and the crankcase. The reason why the screws were loose could not be determined.

3. The number four connecting rod failed due to oil starvation. This accident was not the subject of an on-scene investigation.