Loss of control

After a normal circuit the aircraft crossed the threshold at 85 knots. The pilot advised that the wheels locked as soon as braking was applied. Intermittent brake application had little effect in slowing the aircraft and as the pilot considered that insufficient strip remained to permit a go-around he attempted to ground loop the aircraft. It slid off the side of the strip and collided with a fence before coming to rest. The strip surface was very slippery as a result of overnight rain. Misty rain was still falling as the pilot made his approach and touched down about one quarter of the way along the strip. The pilot had not determined the last point at which a go-around could be commenced and persevered with the landing attempt beyond the point where a go-around could have been safely accomplished.

Circumstances:

The pilot has reported that on the final leg of a competition cross country flight he was forced to make an outlanding. He reported that he flew a full circuit for the selected landing site and completed his checks on the downwind leg. Shortly before touchdown, the glider encountered some turbulence, and the landing gear warning horn sounded. The pilot suspected that the landing gear was not fully locked down. To check the landing gear, he released the speed brake control from his left hand and transferred that hand to the control column. This allowed him to check the landing gear lever with his right hand. During this transfer of hands, he lost control of the glider which impacted the ground and suffered substantial damage. The landing gear was found to be "in-transit" after the glider came to rest. Subsequent investigation by the gliding club showed that the landing gear lever could be moved in its detent such that the warning horn micro-switch operated while the landing gear was still down and locked. It is possible that when the horn operated during turbulence on the approach the pilot moved the gear lever forward which acted to retract the landing gear. The pilot was relatively inexperienced and suggested that when the warning horn sounded, he was startled and moved the landing gear lever in the direction he became used to while recently training in the IS-28 glider. This was opposite to the movement required in the Hornet.

Significant Factors:

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

1. While at low altitude during an outlanding the pilot was startled when the landing gear warning horn sounded.

2. The landing gear mechanism was not correctly adjusted.

3. The pilot changed hands on the control column so he could move the landing gear lever. During this action he lost control of the glider. This accident was not the subject of an on-scene investigation.

The pilot had landed at the strip on a number of previous occasions, but this was the first time in this aircraft type. To give himself more time the pilot made a longer than normal final approach. At about 100 feet above the ground, with the airspeed at about 65 knots, the aircraft began to sink. The pilot applied full power to commence a go-around and as the nose pitched up, the left wing dropped. The pilot did not prevent the nose of the aircraft pitching up, thus aggravating the almost stalled condition of the aircraft. Power was then reduced and the aircraft landed heavily in a wheat paddock along side the strip and slid sideways as it came to rest.

The pilot reported that as he applied full power for takeoff, on strip 32, the aircraft began to swing to the left. He was unable to correct the situation and the aircraft ran off the strip and collided with trees. The wind velocity at the time was reported by the pilot to have been a light south-westerly. The topography surrounding the strip is known to give rise to sudden and unpredictable wind gusts and it is possible that the aircraft encountered such a gust as the takeoff run was commenced.

The student had completed about seven hours training and was undergoing her second session of circuit training. The instructor stated that the student had previously had difficulty with the directional control of the aircraft. On this takeoff he allowed the student to manipulate only the rudder, so that she could concentrate on the directional control aspect, while he manipulated all the other controls. As the power was increased the aircraft gradually swung to the left. Approaching the left side of the strip the swing increased and the instructor applied right rudder at the same time as the student. The aircraft swung to the right and as it crossed the right side of the strip the left wheel dug into the ground and the aircraft tipped onto the left wing.

The pilot was attempting a 300km cross country flight. After release from the aerotow the glider only achieved 3000 feet above mean sea level. As the flight continued no further height gain was achieved and on descending to below 2000 feet the pilot decided to carry out an outlanding. While the glider was being manoeuvred in the circuit, at about 50 feet above ground level, the right wing dropped and struck the ground. The pilot had selected a landing field when flying with 2000 feet indicated on the altimeter. He was unaware that the terrain over which he was flying was 1000 feet above mean sea level and thus only 1000 feet below the aircraft. During the approach the aircraft became low and the airspeed decreased until the aircraft stalled at too low an altitude to allow recovery.

The pilot approached the helipad flying into a 15 knot wind. He overflew the pad and turned left through 180 degrees and overflew the pad again. The helicopter was then slowed to about zero knots IAS and placed in a tight left turn with the intention of approaching the helipad for a landing into wind. After the turn onto downwind was completed translational lift was lost when the pilot reduced airspeed to close to zero knots. The tight left turn was then initiated. The combination of the loss of translational lift and the turn probably required more power from the helicopter than it was capable of delivering. The rotor R.P.M. decayed significantly as the helicopter was overpitched and a high sink rate developed. A passenger, who was a more experienced pilot, took control and attempted to recover rotor RPM but he was unsuccessful. The helicopter impacted heavily with the ground and a pile of gravel and rolled onto its right side.

The pilot had been engaged in glider towing operations for about four months, and had completed 108 towing flights. During the afternoon the pilot had carried out two aerotow flights without incident. On the accident flight a normal take-off and transit to the north side of Korumburra township was made. The glider was released at a height of 2000 feet above ground level and the tug aircraft then turned and tracked towards a right base leg position for the south west landing strip at Leongatha. Not all of this flight was observed, but two witnesses noticed the aircraft descending in a spin to the right. It appeared to recover briefly, with the nose being raised above the level flight attitude, however a spin to the left then commenced. This spin continued until the aircraft disappeared from sight, but the wreckage distribution and impact marks indicated that the pilot had been able to stop the rotation in the last moments of the flight. It was evident that insufficient height remained to effect a full recovery. A detailed inspection of the wreckage did not disclose any defect or malfunction with the aircraft, its engine or systems that might have contributed to the development of the accident. It was considered unlikely that the pilot had deliberately entered a spin on his return to the airfield. The aircraft type is not approved for spinning, and the spin characteristics of this particular two seat conversion are unknown. There was no evidence available to determine how or why the spin situation developed. It was apparent that the pilot had succeeded in partially recovering from the initial spin, however the recovery technique being employed did not prevent a spin in the opposite direction.

The aircraft was taxied in the early dawn light with an overcast sky and drizzle. The aerodrome pilot-activated lights were not on nor were the aircraft landing and taxi lights. The aircraft was inadvertently taxied off the taxiway. During attempts to return to the taxiway the nose-wheel of the aircraft entered soft ground and was broken off.

Prior to flying the club's single seat glider, the visiting pilot was required to undergo a dual check. His first check flight was conducted in VH-IKB by the club's Chief Flying Instructor who was not satisfied and required another flight. The second take-off appeared to be normal but after lift off the glider entered an uncontrolled climb. The pilot operated the cable release and handed over control to the instructor There was no elevator control available and the glider climbed to about 200 feet above ground level where it stalled and turned left through about 90 degrees. The glider descended steeply and impacted the ground on the left wingtip followed by the nose and right wingtip. It came to rest after sliding about 20 metres. After the accident it was found that the cast-alloy elevator horn had failed as the result of a single overload. Examination of the casting revealed widespread and excessive porosity resulting in a degradation of the material static strength including its resistance to impulsively applied loads. The investigation established that, during the previous landing, the glider had touched down heavily and there was a "sharp" impact in the tail area. Prior to the accident flight, the tail of the glider was visually inspected but no evidence was found of any damage. It was not possible to determine positively if the casting failed during the accident or on the previous landing.