Collision with terrain

The aircraft was engaged in dropping parachutists. Prior to commencing the flight the pilot reported that he inspected the airstrip and calculated, from the performance charts for the aircraft, that adequate take-off distance was available. After lift off the aircraft did not climb as the pilot expected. He then turned the aircraft left to avoid trees at the end of the strip. In doing so the left wing struck a dead tree that the pilot had not seen.

A 10cm wide hole was torn in the undersurface of the wing from the leading edge to the aileron. As the aircraft continued to perform adequately the pilot decided to divert to the more suitable airfield at Coolangatta, 30 km to the north. The subsequent landing was without incident. The wind velocity was south-south-easterly at 10-15 knots and the take-off was conducted into wind. 

here is high ground to the north-west of the strip and under certain conditions downdraughts are present in the area of the strip. However, on this occasion the prevailing wind was not conducive to their formation. The reason for the lack of climb performance was not determined.

The student was making a practice glide approach to land, with the throttle in the closed position. Sink developed late on the approach with the airspeed reducing, and full power was applied. The aircraft touched down about two metres short of the sealed surface in a soft area. As the aircraft rolled forward the wheels contacted a 'step' at the start of the sealed area. The contact with the 'step' collapsed the main gear legs and the aircraft slid to a stop.

Significant Factors

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

1. The pilot under supervision misjudged the approach.

2. The instructor was late in assessing the situation and did not ensure power was applied in time to correct the sink rate and descent path.

The pilot reported that during cruise he experienced a loss of engine power associated with rough engine operation. He carried out a precautionary search and landed in a paddock. After landing, the engine was test run and could not be faulted. The pilot, having assessed that the available take-off length and surface conditions were adequate, elected to fly the aircraft from the paddock. The aircraft became airborne later than expected and struck a fence. A landing was made in the paddock immediately past the fence.

The aircraft was being ferried from Bankstown to Perth, a journey expected to extend over several days. During the first sector, the pilots became aware of non VMC weather at Wagga and decided to divert to Cootamundra. It was reported that at about the time this decision was taken, they noticed the left fuel tank was not feeding and that fuel was being drawn from the right tank only. Assuming a fuel system malfunction, and a reduced endurance of about 15 minutes, the pilot-in-command decided to carry out a precautionary landing.

A section of gravel road was chosen for a landing site, as nearby paddocks were unsuitable. Although the touchdown was normal, the aircraft began to veer to the right on the heavily cambered road surface. When the pilot was unable to regain directional control, full power was applied for a go round. The aircraft became airborne, still diverging to the right, and collided with a boundary fence before nosing over into an adjacent paddock. The Skyfox CA 22 aircraft has two fuel tanks, one in each wing, which feed into a common collector tank via a two position, on/off fuel selector. Each tank is vented via a port in each fuel cap.

Asymmetric fuel flow from the tanks is known to occur occasionally and one tank is exhausted first, upon which the remaining tank feeds normally. The manufacturer is expected to soon issue an amendment to the Flight manual by which pilots will be warned by a cautionary note of this phenomenon.

The aircraft and instructors from an aero club were based at Eulan Downs to train a group of five students to the general flying progress test (GFPT) standard. The instructor and student had planned to carry out an upper air sequence prior to returning to Fairfield to commence circuit training. After the completion of the upper air flying the instructor decided to demonstrate a practice forced landing. The forced landing was commenced at 2500 feet above mean sea level (the elevation of the airstrip is 600 feet amsl).

During the descent the instructor found it necessary to adjust his circuit, to ensure a landing on the airstrip, such that a base turn was commenced approximately abeam the threshold and the aircraft aligned on final at about 20 feet above the ground. The instructor reported that the indicated airspeed was 60 knots and the flaps were still selected up when the aircraft was aligned on final. The aircraft stalled at this point and landed heavily on the airstrip. All three legs of the landing gear were torn off and the aircraft slid for about 20 metres before coming to rest.

On the second flight for the day the pilot took off with an identical load as on the first flight, but the aircraft would not climb after liftoff. The aircraft was operating with a tailwind, and it was suggested that a gust may have reduced aircraft performance. The pilot recognised the lack of performance immediately and commenced dumping the load, but the performance did not increase sufficiently to avoid contact with two fences and some scrub. Although the aircraft was damaged, the pilot was able to fly a circuit and land on the strip.

The pilot was conducting his first take off on the strip. The fully loaded aircraft did not accelerate to flying speed by the end of the strip. The pilot had looked out of the cockpit to identify another company aircraft operating in the same area whilst his aircraft was accelerating down the strip. When he eventually found the other aircraft and returned his attention to the aircraft performance, the pilot determined that the aircraft would not clear the obstacles at the end of the paddock, so he commenced a load dump. He attempted to fly the aircraft over the obstacles, but it hit the tops of several low trees and a fence before colliding with a more substantial tree which swung the aircraft around and caused the right undercarriage leg to collapse.

The pilot felt that long grass and soft earth combined with the maximum all up weight of the aircraft to reduce its take off performance. He had thought, from his initial inspection, that there was sufficient length available for take off from the point where he commenced his take off roll.

The pilot advised that, while carrying out a practice forced landing at the conclusion of a local scenic flight, he allowed the aircraft to become too slow and too low. As a consequence the aircraft touched down and nosed over approximately 40 metres short of the runway threshold. The aircraft's left wing and propeller were substantially damaged as a result of the ground contact.

The pilot confirmed that there was no mechanical fault with the aircraft's engine or flight controls that would have contributed to the accident.

On arrival overhead Minlaton, at the lowest safe altitude of 1600 feet above mean sea level, the pilot identified the town and airport. A visual descent to 500 feet above ground level was continued as the aircraft joined the circuit for runway 33. The pilot flew a tight circuit and after aligning the aircraft on final looked into the cockpit for a final check of the power settings. When he looked out, he had lost sight of the runway lights and before he could take corrective action the aircraft struck the ground about 800 metres before the runway threshold.

The left outer wing struck the ground and then a fence and was broken off, the landing gear was torn off and the aircraft came to rest after a ground slide of about 75 metres. The pilot was uninjured and vacated the aircraft unaided.

A second aircraft which arrived overhead Minlaton a short time after VH-CRT, advised Adelaide of the accident. The pilot of this aircraft then held in the area for about 20 minutes because of poor visibility and light before a landing could be accomplished.

The pilot was conducting a scheduled passenger service flight from Port Augusta with a stop at Innamincka. A commercial pilot, travelling as a non-paying passenger, occupied the co-pilot's seat to observe the operation. Two additional passengers were on board the aircraft for the entire flight.

After landing at Innamincka, the aircraft was refuelled by the pilot in command and the oil levels of both engines were checked by the observer, who experienced difficulty securing the combination oil filler cap-dipsticks. He asked the pilot for instructions and, although some advice was given, the pilot did not check the security of the dipsticks.

Take-off was commenced towards the north into a 10-15 knot wind with a surface temperature of about 20 degrees C. Shortly after lift-off, at the first power reduction, the observer in the co-pilot's seat advised that there was oil seeping back along the cowl from the right-side oil filler hatch. The pilot reported that he increased power to both engines but believed there was no response from the right. He began an immediate left turn to complete a circuit and attempted to secure the right engine and feather the propeller. The aircraft then began a roll to the right, the nose dropped, and the aircraft impacted the ground. As the aircraft rolled right and the nose dropped, the pilot reported that he had secured the left engine and feathered the propeller. The observer in the co-pilot seat reported hearing a continuous stall warning horn as the right wing began to drop.

All occupants, although injured, were able to vacate the aircraft through the main cabin door. The pilot provided assistance to the passengers and then returned to the airport to summon help.

Examination of the wreckage revealed that the aircraft impacted the ground in a nose down, right wing low attitude while turning right. The landing gear collapsed due to impact forces and the right wing separated. Deceleration and impact forces were severe. The right propeller was found in the fine pitch range with no damage to the uppermost blade and the other two bent backwards. The right engine oil filler cap-dipstick was found to be correctly installed in the oil filler neck. There was a pattern of engine oil over the rear of the engine and inside the cowl originating from the oil filler neck.

The left engine was partially torn from its mountings and displaced about 90 degrees to the right. Its propeller was in the fully feathered position. The oil filler cap-dipstick was on the ground adjacent to the engine. An oil spill pattern similar to that on the right engine was evident.

The pilot in command held a Senior Commercial Pilot Licence, a Command Instrument Rating, and a current Class 1 Medical certificate. He was endorsed on the aircraft type and had last been checked in emergency procedures eight months previously.

The person in the co-pilot's seat had recently qualified as a commercial pilot and had completed some flying training with the operator. He was on board the flight to observe a typical commercial operation to enhance his employment prospects as a pilot. This observer status had been previously granted to other pilots. The company management provided strict guidelines to pilots in command of such flights regarding the non-active role of these observer pilots.

The aircraft maintenance release was valid, and the aircraft had been loaded within the Flight Manual maximum weight and centre of gravity limits at the time of the accident.

The right engine was run on a test stand and assessed as being capable of normal operation. The combination oil cap-dipstick prevented oil loss when correctly inserted and clipped down. When in place but not clipped down, with the engine running above 1800 rpm, an oil leak pattern similar to that seen at the accident site occurred over the rear of the engine.

It is considered likely that the dipstick had been loose prior to impact but was correctly replaced in the filler neck after the accident. The design of the oil filler system tends to restrict oil loss with a loose dipstick. This condition would not require an immediate reaction by the pilot to prevent engine damage.

The right propeller was dismantled for inspection and found in the normal fine pitch range but capable of feathering. The uppermost blade was not damaged and backwards bending of the other two blades indicated that it was stationary or rotating slowly at impact.

Severe impact damage to the left engine precluded a test run. It was bulk stripped with no defects evident that would have prevented normal operation. The left propeller was dismantled and found to have been in the fully feathered position prior to impact. Damage sustained would indicate that it was stationary or rotating slowly at impact.

Based on the physical wreckage and impact examination and on the pilot and passenger comments, it is evident that when the pilot secured the right engine and began the left turn, the airspeed dropped, and the aircraft stalled. When the right wing dropped the aircraft entered an incipient spin. Due to the low altitude at which control was lost, the pilot was unable to effect a recovery.

Findings

1. The aircraft had a valid maintenance release and was within maximum weight and centre of gravity limitations at the time of the accident.
2. The pilot-in-command was correctly licensed and endorsed for the aircraft type.
3. Oil levels had been checked and oil added to the right engine by a non-crew member.
4. The combination oil cap-dipsticks had not been checked for correct installation by the pilot-in-command and were probably loose at take-off.
5. The oil filler design of the engine will restrict oil loss when a dipstick is not correctly secured.
6. The left propeller was feathered, and the right propeller was in the fine pitch range; both were stationary or rotating slowly at impact.
7. The right engine was capable of normal operation and was successfully run on a test stand after the accident.
8. Impact damage to the left engine precluded a test run but a strip inspection indicated that it was capable of normal operation.
9. The aircraft stalled and entered an incipient spin to the right prior to ground impact.

Significant Factors

1. The pilot-in-command reacted inappropriately to a perceived engine problem shortly after take-off.
2. Control of the aircraft was lost at a height insufficient to effect a recovery.