At the time of the accident, the Cessna 210 was for sale. The pilot had conducted a pre-purchase inspection, including an engine run, the day before the accident. On the day of the accident, the pilot and two passengers boarded the aircraft for an evaluation flight to a nearby aerodrome. Following an uneventful engine run-up, the aircraft was observed to take off from runway 31R and flew for approximately 2.5 km at low level. The pilot subsequently carried out a successful ditching into a water-filled quarry. The pilot and both passengers successfully exited the aircraft but one passenger, who was unable to swim, drowned before reaching land.
The aircraft was manufactured in 1965 and had accumulated 8,013 airframe hours. All required maintenance had been performed and the aircraft had a current maintenance release, which listed no outstanding unserviceabilities.
During most of the previous year, the aircraft was in short-term storage at Mt Gambier SA. Approximately four months before the accident, a rough running engine was noted in the aircraft logbooks. The problem was later diagnosed as a cracked number 4 cylinder. The cylinder was subsequently replaced and the aircraft's 100 hourly inspection was carried out on 26 November 1999. On 24 December 1999, the aircraft was refuelled at Mt Gambier and flown to Moorabbin, Vic. by a ferry pilot who reported that the engine and aircraft performed normally. Except for one short flight five weeks before the accident, the aircraft remained on the ground until the accident flight. The engine was started and ground run four days before the accident flight. During the ground run, the pilot, who was not the accident pilot, noticed that the fuel selector valve was stiff but did not record the problem on the maintenance release.
Examination of the aircraft after it had been recovered from the quarry found that the flaps were at approximately the 10 degree position and the landing gear was retracted. Visible damage to the exterior of the airframe was limited to distortion of the main landing gear doors. The line to the manifold air pressure gauge was broken at the engine firewall. The throttle was in the idle position, the propeller control was in the full fine position and the mixture control was in the fully rich position. However, as the recovery of the aircraft from the quarry probably distorted the engine mounts, the positions of engine controls were not considered reliable. The magneto switch was in the BOTH position and both fuel pump switches were OFF. All engine instruments displayed readings that were consistent with a non-operating engine.
Engine and propeller
After recovery, the Teledyne Continental IO520 engine was dismantled for examination and all appropriate fuel and ignition system components were removed and tested. The propeller was examined and its governor bench tested. No fault that could have produced a significant loss of power was found with either the engine or the propeller. No blockages or loose baffles were found in the exhaust system.
The fuel selector valve handle was found in the left tank position but the selector valve, which is connected to the handle by two linkages, was found in the position of partly open to the left tank. The movement of the valve was stiff and the linkages were worn, allowing the movement of the valve to lag behind the handle, thereby giving a false indication of the valve's true position. The inside of the valve was corroded and the detent in the left tank position could not be felt when the valve was tested.
Fuel system testing
The position of the fuel selector valve had been index marked on the valve before its removal from the aircraft. The valve was rotated to the indexed position four times during testing and the flow rate measured. The measured flow rates at the indexed position varied between a minimum of 90 pounds per hour (PPH) and a maximum of 280 PPH. The engine manufacturer's specifications for the fuel system stated that the required fuel flow at full power was between 136 and 146 PPH. The engine manufacturer advised that with the fuel flow restricted to 90 PPH, this engine would develop approximately 75% of maximum power. The owner's manual stated that normal cruise power setting should be between 65% and 75% of maximum power.
When all the fuel system components, except the fuel selector valve, were connected to a test rig, they were confirmed to be capable of delivering to the engine a fuel flow that was slightly in excess of the engine manufacturer's specifications.
Approximately 60 litres of fuel was drained from each wing tank after the aircraft was recovered from the quarry. When tested, that fuel was the correct type for the aircraft. A small amount of free water was present in the fuel. Ethylene Diamine (EDA) was the contaminant involved in the aviation gasoline contamination problem that occurred in southern Australia over the December 1999/January 2000 period. There was no EDA detected in the fuel samples taken from the aircraft, nor were any of the deposits, that are typically produced by EDA, found in any fuel system components.
The pilot had held a Commercial Pilot Licence since 1962 and an Air Transport Pilot Licence since 1982. He had flown more than 13,000 hours on a range of aircraft including multi-engined turboprop aircraft. Since 1997, he had flown approximately 1,200 hours on Maule floatplanes and in the three months to the accident, almost all his flying had been on this type. He last flew an aircraft from the Cessna 200 series approximately three months before the accident, however, he had not flown the accident aircraft since 1966. He was correctly licensed and endorsed for the flight.
Six people located around the aerodrome witnessed the aircraft takeoff. Their evidence was consistent on the following points:
- the aircraft engine ran normally during start, taxi and run-up,
- the engine note during the latter stages of the takeoff and the initial climb was unusual for the aircraft type,
- the aircraft became airborne at a point between 2/3 and 3/4 along the runway,
- the landing gear began retracting as soon as the aircraft left the ground, and
- the aircraft's angle of climb after takeoff was lower than normal.
Of the five witnesses who heard the aircraft takeoff, four reported that the engine sounded as though it was running smoothly at less than full power. The fifth witness reported that the engine sounded uneven, as though it was "running on only four of its six cylinders".
The pilot reported that on the day before the accident and the day of the accident, the aircraft's engine had started and run without difficulty. Both fuel tanks were dipped and found to be slightly less than one quarter full. For the accident flight, the fuel selector valve remained in the left tank position from the engine start until the aircraft ditched. The engine run-up, that did not include a full power check, had not shown any unserviceabilities with the engine. The takeoff was normal until the landing gear was selected up. The pilot recalled that at that point the aircraft experienced a gradual loss of performance and was unable gain any further altitude. He recalled that after takeoff the manifold air pressure gauge read 22 inches which is approximately 5 inches less than would be expected. The pilot reported that when he realised that the aircraft would not make it back to the aerodrome, he decided to land in the first clear area that he saw. When the water-filled quarry came into view, he decided that a ditching was the best option available to him.
Performance of accident aircraft
The evidence of the ground witnesses and the pilot was consistent on the following points.
- No sudden loss of performance occurred.
- The aircraft displayed lower performance than expected after takeoff; however, it was still able to climb to a height of between 50 ft and 100 ft.
- The aircraft was unable to maintain height during the later stages of the flight.
Data provided by the aircraft manufacturer indicated that a Cessna 210E aircraft with 10 degrees of flap extended, would become airborne after a takeoff run of 104 metres, under the same conditions as the accident aircraft experienced. Eyewitness statements indicated that the aircraft did not leave the ground until it was at least two thirds of the distance along the runway, a distance of 748 m. That represented a takeoff run 719% longer than expected.
The aircraft manufacturer advised that the operation of the hydraulic pump during the landing gear retraction cycle in a normally operating Cessna 210E aircraft consumed approximately 7 horsepower, which was 3.8 % of the engine output at the maximum power setting. That would result in a small reduction in climb performance during gear retraction. In addition, the drag of the landing gear doors, which open during the retraction cycle, would also reduce the aircraft's performance by a significant margin. If the engine was producing less than maximum power, the percentage loss of performance during the landing gear retraction cycle would be proportionally greater.
The distance required to stop the aircraft, if the takeoff had been rejected from the lift off point, would be approximately equal to the landing ground roll distance under the same conditions. From the lift off point, the aircraft had 750 m to run before the aerodrome perimeter fence. Half of this distance was sealed runway; the other half was level grass. The manufacturer's data showed that at maximum weight, 233 metres would have been required to stop on a grass runway.
Performance of pilot's most recent aircraft type
The Maule floatplane, the aircraft that the pilot had flown most often in the previous three months, at maximum weight had a takeoff run of approximately 500 m from smooth water and longer from rough water. Compared to a fully serviceable Cessna 210E aircraft, the Maule floatplane normally required a longer takeoff run and had a much lower rate of acceleration.
In 1984, a US registered Cessna 210 sustained total power loss in-flight and the pilot force landed the aircraft. A factor in the accident was the use of the auxiliary fuel pump in the high position (NTSB CHI84FA282). In 1976, an Australian registered Cessna 210 was damaged in a force landing after the engine lost all power as a result of incorrect use of fuel pump in the high position (BASI 197606853). The owner's manual stated that the electric fuel pump should not be switched to the high position during normal operation because richer mixture than normal will result.
In 1972, a Cessna 210 was damaged in a force landing after the engine lost all power. A factor contributing to that accident was the prolonged sideslipping of the aircraft with low level of fuel in the tanks. (BASI 197204960). The owner's manual advised that with fuel tanks one quarter full or less, prolonged uncoordinated flight can uncover the fuel tank outlets, causing fuel starvation and engine stoppage. It further advised that "prolonged" means more than one minute.
ATSB records contain reports of four accidents (BASI 197304110, 198101450, 198201391, 198802338) involving Cessna 210 aircraft in which vapour lock in the engine fuel system resulted in complete power loss.
A comparison of the takeoff run used by the aircraft and that predicted by the manufacturer shows that the aircraft's performance during the takeoff was significantly less than expected. The fact that the aircraft could get airborne and slowly climb, but later could not maintain altitude with the landing gear retracted indicates that the aircraft's performance decreased during the flight. As the pilot and the witnesses agreed that no sudden loss of performance occurred, it was concluded that a slow deterioration in engine power output occurred over the period of the flight. As the takeoff run was longer than expected, this deterioration began at the start of, or during, the takeoff run.
The reduction in performance that was felt by the pilot after takeoff was consistent with the normal loss of performance produced by the gear retraction.
A loss of performance of an aircraft can be due to an increase in drag, a decrease in power from the engine, environmental factors such as down draughts, or a combination of these factors. An increase in drag can be the result of:
- damage to the airframe,
- a configuration change (flaps or gear extended), or
- poor technique by the pilot (for example, incorrect airspeed or unbalanced flight).
An increase in drag is not considered a likely explanation for the degraded performance for the following reasons:
- After the accident, there was no damage evident other than that which was consistent with the circumstances of a ditching and recovery.
- The aircraft was recovered with landing gear retracted and flaps at the 10 degree position.
- It is considered unlikely that an experienced pilot who was current on single-engined, light aircraft could mishandle the aircraft to an extent that would have produced the observed performance.
As no other aircraft flying at the time experienced difficulty in climbing after takeoff, environmental factors are not considered to have contributed to the degraded performance of the accident aircraft. This leaves a reduction in engine power as the most likely explanation for the degraded performance. This is also supported by the witness evidence that the engine note on the accident flight was unusual for the aircraft type.
As no fault could be found with the engine and propeller, other reasons for the power loss were considered. Taking off with the propeller control in the cruise position would have produced sufficient power for the aircraft to maintain altitude or to climb slowly. Selecting the fuel pump to the high position would have produced a total loss of power (as shown by previous accidents) or a sudden, substantial loss of power, not the gradual loss of power observed. Fuel starvation resulting from prolonged, unbalanced flight with less than one quarter full fuel tanks would have produced a sudden, total loss of power. Vapour lock in the fuel line would also have produced total loss of power. The ambient conditions were not conducive to induction system icing.
The observed performance of the aircraft was consistent with a restriction in the fuel supply line. If such a restriction existed, it would only have become apparent at high power settings; it would not have shown up during the engine runup. At medium and low power settings, sufficient fuel could flow past the restriction to produce normal engine power output and indications. However at high power settings, such as takeoff power, the engine would consume fuel at a faster rate than could flow past the restriction. A high power output would be produced for a short period as excess fuel in the engine fuel system was consumed. As the amount of excess fuel reduced, the engine power output would progressively decrease until the rate of fuel consumed by the engine equalled the rate of fuel passing through the restriction.
The partially open fuel selector valve would have restricted the fuel flow to some extent, but should have allowed the engine to produce sufficient power to maintain altitude or slowly climb. The fact that the aircraft was apparently unable to maintain altitude during the later stages of the flight indicates that the partially open fuel selector valve, on its own, does not explain this accident. The partially open fuel selector valve could have restricted the fuel flow to a greater extent and produced the observed aircraft performance if:
- dirt or other foreign matter further obstructed the partially open port in the fuel selector valve, or
- during the accident flight, the fuel selector valve was in a "more-closed" position than when the aircraft was recovered (only one or two millimetres of movement would have been needed).
Although the pilot had sufficient distance in which to reject the takeoff at any point up until liftoff, he was unfamiliar with this specific aircraft and its expected performance. Even though the takeoff run was longer than predicted, it was similar to the takeoffs in the Maule floatplane that the pilot was most familiar with and to him, may have appeared normal. That perception was reinforced by the lack of any obvious changes in engine indications or aircraft performance during the takeoff. The first indication the pilot perceived of the deteriorating performance was when the aircraft was slow to climb as the landing gear was retracting. Rejecting the takeoff at this point may have presented a serious risk to the aircraft and its occupants. It was concluded that the pilot did not perceive that the takeoff was abnormal until he was past the point at which the takeoff could be safely rejected.
The report by the pilot of seeing 22 inches of manifold air pressure after takeoff could not be reconciled. Such an indication could only be produced by a blockage of the engine induction system or by the throttle valve closing. Examination after the accident found no blockages and the throttle linkages were operating normally. However, in a high stress situation and in an aircraft type that he had not flown recently, the pilot may have misread the manifold air pressure gauge.
Although the observed performance of the aircraft was consistent with a restriction in the fuel supply system, the reason for the low power output from the engine could not be conclusively determined.
|Date:||18 March 2000||Investigation status:||Completed|
|Time:||1310 hours ESuT|
|Location:||2.5 km NNW Moorabbin, Aero.|
|Release date:||27 September 2001|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||Fatal|
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Private|
|Damage to aircraft||Substantial|
|Departure point||Moorabbin, VIC|
|Departure time||1309 hours ESuT|
|Destination||Point Cook, VIC|
|Role||Class of licence||Hours on type||Hours total|