The aircraft was crulstng in a southerly direction at an altitude of 4500 feet above mean sea level in clear weather conditions north of Mansfield when there was a substantial loss of engine power and smoke issued from the engine and entered the cabin. The pilot checked the engine controls and selected the mixture control to the idle cut-off position. He made a distress radio call to the Melbourne Flight Service Unit and reported that he had a suspected engine fire and intended to make a forced landing two miles north of Mansfield. A field to the left was selected by the pilot as being suitable for a forced landing and he planned to fly down the western side of the field and make a left turn of about 180 degrees to land to the north into a light northerly surface wind. As the aircraft descended the undercarriage was selected down and a left hand turn was commenced but, as the turn progressed,the pilot decided that the field which he had selected was unsuitable and that he would now land in the field adjacent to and to the west of that originally selected. At this stage the starboard wing dropped and, despite recovery action taken by the pilot, the aircraft veered to the right until it was heading some 45 degrees to the right of the intended final approach path at a very low height. The aircraft then struck the upper limbs of a large gum tree at a height of about 50 feet, passed through the upper section of the tree and dropped steeply' into a nearby small dam coming to rest in a level attitude in water some four feet in depth. Subsequent investigation indicated that the engine power loss was the result of an in-service failure of the No. 4 cylinder connecting rod big end bearing as a result of which the connecting rod had fractured and penetrated the crankcase.

On 16 August, 1973 a Piper PA30/160 aircraft, registered VH-MEM, crashed into the southern slopes of Mount Neville whilst on a private travel flight from Branxton, New South Wales, to Archerfield, Queensland. The four occupants were killed and the aircraft was destroyed. Examination of the wreckage failed to reveal any evidence of pre-impact structural failure, malfunction of systems, or any mechanical evidence which might have contributed to the accident. At the moment of impact the aircraft was in a climb and the engines were heard at high power immediately prior to impact. The height of the last sighting, the distance travelled and the impact height are in general agreement with the aircraft's normal climb capability. It is apparent, therefore, that the pilot did not appreciate the very dangerous relationship between the aircraft's climb capability and the rising terrain ahead.

The aircraft commenced operations from an agricultural airstrip on Warrawee Station at about 1100 hours on the day of the accident and, on each flight, some 860 kg of superphosphate was uplifted and spread on properties in the area. At about 1200 hours, when 13 flights had been completed, operations ceased temporarily while the personnel concerned had a meal break. The aircraft was then refuelled, operations recommenced about 1230 hours and six further flights were completed. After being reloaded with superphosphate, the aircraft commenced another take-off but at a point some 44 metres along the take-off path, the nose wheel support assembly collapsed. The aircraft skidded for 7 metres on the collapsed assembly until the structure dug into the ground and the aircraft nosed over. The pilot's compartment was partially crushed as the aircraft came to rest in an inverted position.

On 23 January, 1973, a Cessna 150G aircraft registered VH-KPH disappeared whilst on a travel flight from Latrobe Valley, Victoria, to Merimbula, New South Wales and no trace has been found of the aircraft or its occupants. An intense air, sea and land search commenced at first light on the next day and continued until 13 February 1973. Civil and military aircraft involved in the search flew 166 hours and covered an area in excess of 8000 square miles, within which the high probability areas were searched many times. Twenty-five sighting and hearing reports were investigated but no trace was found of the aircraft or its occupants.

Early in the day the pilot flew the aircraft from Mudgee to the airstrip situated about 4 mile south of the property on which superphosphate was to be spread. The weather was fine, the wind was calm and visibility was unrestricted. Although the pilot did not carry out a ground or aerial inspection of the property prior to commencing operations, nor did he obtain a specific briefing regarding the location of power lines on the property, he had carried out similar operations on this property periodically during the previous five years. As the aircraft approached the power line it banked to the right, apparently to follow the change in boundary direction and the raised left wing tip struck the cables resulting in a portion of the wing leading edge and upper surface fabric being detached. The aircraft slewed and rolled to the left and struck the ground In an inverted attitude 460 feet beyond the power line where it came to rest against a post and wire fence. A fierce fire occurred immediately.

Early In the day the pilot flew the aircraft from Bathurst to an airstrip on a property at Hobby's Yards arriving at about 0630 hours. In conjunction with the pilot of another aircraft operating from the same airstrip it was planned to spread superphosphate on a lightly timbered, relatively flat area. The weather was fine, the wind was calm and the visibility was unrestricted. The aircraft took off in a westerly direction and turned right as before to proceed northward to the nearby spreading area. This flight path entailed about 40 feet high, aligned east-west and flying across a line of widely spaced green gum trees, generally situated outside the spreading area. As the aircraft crossed this line of trees it struck the upper limbs of a dead tree which extended some 30 feet above the general height of the green gums. The aircraft crashed to the ground in a steep nose-down the dead tree.

At a speed estimated by the pilot as 80 knots, he observed fluctuations in the oil pressure gauge of the port engine and he closed both throttles and abandoned the take-off. The tail of the aircraft was well off the ground at this stage, the pilot therefore attempted to lower the tail but the aircraft became airborne for a short period. He then took control action to return first the mainwheels and subsequently the tail wheel to the runway. When all three wheels were on the ground, heavy braking was applied but the aircraft over-ran the runway, continued through the prepared over-run area and finally ran into a creek some 180 metres beyond the sealed end of the runway.

The operation was to spray a sorghum crop in an approximately rectangular field aligned north-east/south-west. There were four isolated trees in the field and a single wire power line was located 80 feet outside and parallel to the north-east boundary. The wire was supported between two poles 890 feet apart and the height of the wire varied between 34 feet above the ground at the pole adjacent to the northern corner of the field and about 24 feet at the centre of the span. The field contained two crops of different ages on alternating contour strips and, as only the younger crop was to be sprayed, it was necessary for the pilot to turn the spray on and off four times on each run along the field which was approximately 3000 feet in length. Because of the curved contours the positions along each run at which the spray control was operated would vary. During the day there were four telephone contacts concerning the proposed operation between representatives of the operator and the farmer or his representative but the farmer did not have the opportunity to speak directly to the pilot and thus brief him regarding the power line. The pilot had not previously treated this particular field but he had operated over adjacent fields and properties. The farmer and a neighbour acted as markers and when the aircraft arrived overhead they moved into positions at either end of the field. The pilot made a brief aerial inspection and commenced operations running north-east and south-west alternately. On each of the first three runs in each direction the aircraft passed under the power line and the circumstances suggest that the pilot was aware of its presence. The seventh run was made towards the north-east and, at its completion, the aircraft commenced to pull in the vicinity of the boundary fence which was earlier than on previous runs. The aircraft then struck the power wire in a nose up, port wing down attitude. The wire became caught on a flood light which was mounted on the underside of the port wing. The aircraft veered sharply to the left before the wire wrenched out the light and the internal wing drag strut assembly on which the light was mounted. The aircraft continued rolling to the left as it climbed to a height of about 50 feet and it then dived into the ground in an inverted steep nose down attitude and burst into flames.

During the afternoon the aircraft had been flown to the property of a friend of the pilot, 36 miles to the north east of Kellerberrin and whilst there, had been flown by the property owner. A few minutes after departing on the return flight the aircraft was seen circling at a height of about 500 feet over the property of another friend of the pilot some 15 miles north of the direct track to Kellerberrin and it then departed in the general direction of its destination. The aircraft was next sighted by the owner of this property who had not been at home when the aircraft first circled his house, but was returning there by car from Doodlakine. He saw the aircraft for a short period, flying at 600 to 800 feet above ground level, about one third of a mile to the right of the road on which he was travelling and on a parallel northerly course. He then lost sight of the aircraft because of trees lining the road. After travelling for a further two miles to the north, the property owner made a 90 degree turn to the right and from this road he had a clear view across the paddocks to the south. He sighted the overturned wreckage of the aircraft approximately one mile to the south of his position and some 150 feet east of the alignment of the road which he had just left. The aircraft undercarriage had caught the top wire of a power transmission line which crossed the paddock from east to west at a height of about 30 feet. The aircraft had then pitched sharply nose down and had struck the ground in an almost vertical attitude 145 feet north of the point of contact with the wire. The nose dug in to the surface of the paddock which was soft from recent rains. The engine was torn from the airframe and the main wreckage came to rest inverted some 36 feet beyond the area of initial impact with the ground. Examination of the wreckage showed that the flaps were up. There was no defect discovered in the aircraft which could have contributed to the accident and there is evidence that the engine was operating normally up to the time of impact.

The aircraft was engaged in the transport of men and materials In connection with the installation and maintenance of conveyor belting. The flight had commenced at Maitland, New South Wales, on the previous day and, prior to departure, the pilot had loaded the aircraft with a quantity of heavy, low volume materials. With one passenger on board, the flight to Groote^Eylandt had been uneventful. At Groote Eylandt the main and wing tip fuel tanks were replenished for the final stage of the flight to Gove. Before tlie aircraft began its departure from Groote Eylandt, two more passengers, their baggage and further materials of trade were loaded on board and distributed by the pilot. The weather was fine and clear and the wind was calm.

After the engines were started, the aircraft taxied to the eastern end of the 6,240 feet long bitumen runway and Phen commenced a take off into the west. Following a ground run of about 3000 feet the aircraft became airborne and entered a gentle climb. The nose of the aircraft was then seen to rise, the climbing angle increased abruptly and the aircraft climbed steeply to a height of some 300 feet. At this point the port wing went down very quickly until the aircraft was banked almost vertically. The ncse then dropped and the aircraft entered a flat, left hand spin from which it did not recover.

The aircraft struck the ground at a position 150 feet to the left of the runway centreline and 4480 feet from the eastern end of the runway. The undercarriage was found to have been down at impact and there was no fire. It has been calculated that, before the flight began, the loaded aircraft weighed 4433 pounds, which is 705 pounds in excess of the maximum permissible gross weight and the centre of gravity, with the undercarriage down, was located 3.9 inches aft of the rear limit specified for the aircraft type. This loading configuration could lead to the aircraft entering an uncontrolled nose pitch up condition with insufficient stabilator control available to correct the situation. There was no defect of the airframe or engines which could havo contributed to the loss of the control experienced.