Loss of control

The pilot was landing in gusting wind conditions with a cross-wind from the left. After the left wheel had touched down and before the right wheel had been grounded a gust of wind lifted the left wing, causing the aircraft to drift to the right. Attempts by the pilot to re-land were unsuccessful and a go-around was initiated. The aircraft subsequently collided with a fence post and came to rest about 180 metres off the side of the runway. The aircraft encountered a very strong wind gust at the time of touchdown. The pilot delayed action in initiating a go-around and when power was applied the aircraft was unable to out-climb the rising terrain while flying downwind.

Circumstances:

The pilot reported that there had been recent heavy rain on the strip. Well into the landing roll, the aircraft encountered an area of water and skidded to the left. The left wheel then entered soft ground and swung the aircraft further left, resulting in the left main landing gear striking a steel framed cone marker. This accident was not the subject of an on-site investigation.

Circumstances:

The pilot had continued gliding at altitude despite deteriorating weather conditions. When he returned to the circuit, he found that a strong wind was blowing. During the approach to land the pilot found that he had to hold a heading up to 45 degrees off runway heading to counter the right crosswind. After flaring to land the glider drifted and weather-cocked. It came to rest after passing through a barbed wire fence.

Circumstances:

The aircraft was making a crosswind landing on runway 22. The pilot reported that as the aircraft was touching down on the main wheels it was struck by a strong gust, blowing it from the centreline. Because grassed areas were available, the pilot did not attempt to regain the centreline. The aircraft continued to diverge from the runway until it struck a ditch.

Circumstances:

The aircraft took off, made one circuit of the field, and was flying parallel to the take-off direction at approximately 250 ft when it was observed to dive almost vertically into the ground. The engine was operating at a high-power setting at impact, and no faults were found with the aircraft which may have been factors in the accident. The factors which led to the loss of control could not be determined.

Circumstances:

The pilot was landing at a property prior to conducting crop spraying. During the landing roll, the aircraft veered off the strip and overturned in a wheat crop. A subsequent investigation established the left mainwheel hub had failed due to a fatigue crack, allowing the wheel to travel up the landing gear leg. A partial collapse of the left leg then resulted when the axle dug into the ground. The crack had originated from corrosion pitting on the inner wheel half interior surface, which was not visible with the wheel in situ.

The pilot was landing on a property strip in gusty crosswind conditions. Directional control was lost during the landing roll and the pilot was unable to prevent the aircraft from running off the side of the strip. As he attempted to taxi the aircraft back onto the strip the nosewheel entered an area of soft sand and subsequently collapsed. The particular strip in use was only 20 metres wide, and consequently did not meet the requirements for an Authorised Landing Area. The strength of the crosswind component could not be determined.

Circumstances:

The aircraft was landing downwind on an agricultural strip. During the landing roll the aircraft departed the left side of the strip following the failure of the right brake coming to rest inverted in a rice paddy. The investigation found the right brake master cylinder had buckled in the reservoir area. The buckling and resultant misalignment of the piston rod caused a bending failure of the rod and liberation of the piston with a subsequent loss of hydraulic pressure to the right brake. The reason for the failure of the master cylinder was not determined. There are no other recorded accidents involving master cylinder failures in this type of aircraft. The failure is therefore considered an isolated case.

Significant Factors:

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

1. Material failure of the right brake master cylinder piston rod.

2. Loss of hydraulic pressure to the right brake.

3. The pilot was unable to maintain directional control on the landing roll.

This aircraft was intended to be the production version of the "Stratos" aircraft. The prototype version had successfully flown some 340 hours. The production model incorporated significant changes made by the designer/pilot. These changes included the removal of the dihedral from the main wing and the use of full span elevators on the canard wing and full span ailerons on the main wing. The engine mounting was lowered such that the ducted propeller was totally below the main wing and the lower part of the propeller duct was extended well forward to form a "channel or strake". The main purpose of the "channel wing" was an attempt by the designer to lower the stall speed of the aircraft to 30 knots and to reduce both landing and takeoff speeds and distances. As far as the investigation could determine, the effect of these modifications had not been checked by wind tunnel or other methods prior to this flight. On the day of the accident the pilot and his assistants had worked at the factory preparing the aircraft for testing. The preparation included a determination of the centre of gravity, although no record was kept of these calculations. Following these preparations the aircraft was loaded onto a trailer and taken to Penfield. The weather conditions at the time were fine, with light winds. The pilot subsequently carried out a series of taxying tests, to establish the optimum position for the control column. He then conducted a take-off, and operated in the local area for about 17 minutes. Witnesses reported that the aircraft then carried out a very slow pass over the aerodrome at a height of between 400 and 500 feet above ground level. About one minute later it was seen to turn back towards the strip. However, shortly after the turn was completed, control of the aircraft was evidently lost. It is uncertain whether the aircraft suddenly pitched nose up or nose down, but all witnesses agreed that it then fell vertically while the nose swung in a pendulous motion. The aircraft struck the ground in an inverted attitude with little or no horizontal speed. An inspection of the aircraft found that all airframe components were essentially intact and there was no indication of any airframe or control failure prior to ground impact. The engine was test run and strip inspected and no fault could be found. No aerodynamic testing was carried out on the airframe to determine the likely effect on performance of the various modifications made to this aircraft. However, given that the prototype appeared to suffer no adverse flying characteristics, it is possible that the modifications incorporated in the new aircraft had an adverse effect on the stall characteristics. Analysis of the modifications indicates that the most significant effect on the stall characteristics would have resulted from use of full span elevators on the canard wing. The use of full span elevators results in a relatively uniform loading of the canard as the elevator is deflected approaching the stall. The result is that the canard would be developing more lift, compared to the same wing without full span elevators, before the wing stalled and the stall would be sharper. Because the main wing is still producing lift at this stage the nose down pitch following the stall of the canard would be aggravated. It is considered likely that the accident sequence was initiated by a full canard stall followed by a rapid nose down pitch. Also, the altitude at which the flight was conducted would not have allowed the pilot time to make the necessary corrective control imputs following the stall before the aircraft impacted the ground.

Circumstances:

The student was authorised to conduct solo circuit practice in generally light easterly wind conditions. During the session, the wind began to swing through more than 90 degrees, with associated strong gusts. In the landing flare on the circuit prior to the accident, a wind gust lifted the left wing and rolled the aircraft to the right. Experiencing considerable difficulty, the student regained control and climbed the aircraft for another circuit. Being unsettled, the student forgot that he could seek advice from his instructor through Perth Flight Service. He elected to terminate the session with his next landing. Again, as the student flared the aircraft for landing, a strong gust lifted the left wing, rolling the aircraft to the right. Before he could correct the roll, a second gust struck the aircraft. Despite recovery efforts the student realised he was losing control and attempted to go-around. The aircraft with a bank angle of 50 degrees, stalled and contacted the ground right wing tip first, coming to rest 95 metres from the runway centre line.