Mr. Armstrong purchased the aircraft in June, 1972 and later that year, assisted by two other persons also not authorised to perform such work, modified and fitted to the aircraft a long range fuel tank of unknown history. This work was not recorded in the aircraft log book as is required. The aircraft subsequently underwent a major inspection followed by some 60 hours flying before again being delivered to the owner during September, 1973. Mr. Armstrong then flew the aircraft on various occasions totalling some 11 hours although, being the holder of a student pilot licence, he was not authorised to pilot any aircraft unless he was under the supervision if a flight instructor.

The aircraft was engaged In amphibious operations and was equipped with two landing floats, each fitted with a nose wheel and a main landing wheel. The wheel units, normally extended for surface operations on land, are designed to retract into recesses in the floats and it is essential that they be in the retracted position whenever the aircraft alights on water. The position of the wheel units at any particular time is Indicated to the pilot by lights in the cockpit. Additionally, the position of portions of the mechanism for retracting and extending the wheel units can be viewed from the cockpit through a small clear panel on the top of each float.

The pilot, an American national, had gained his helicopter flying experience mainly as a member of the United States military forces. Prior to obtaining employment with the Operator in June, 1973, he obtained Australian commercial helicopter and fixed wing pilot licences as well as an agricultural pilot rating for fixed wing aircraft. He subsequently undertook a short additional course of helicopter flying and was granted approval to conduct cattle mustering operations. Following a period of operation under supervision, the pilot commenced un-supervised operations in VH-WHR on 22 September, 1973 and, on the day of the accident, he was engaged in mustering cattle to a base camp on a property adjacent to Calwynyardah Station.

The sediment sampling on which the helicopter was engaged involved a series of flights, each of the order of two to four minutes duration. Between individual flights the aircraft remained on the ground with the engine running for the short period required for the rear seat passengers to disembark, collect sediment samples and re-embark for the flight to the next selected location. The passenger in the left hand rear seat would then signal, by tapping the pilot on the shoulder, that both rear seat occupants were strapped in and take off could commence. Conditions in the area were hot and dry and at each take off and landing the rotor wash raised targe quantities of dust.

The area which was available for take-off was aligned east/west, 3,000 feet in length and 160 feet wide, and its surface was a short crop stubble. A wire fence three feet six inches high formed the northern and western boundaries and the area was bounded to the south by a standing crop. The Flight Manual of the aircraft required a distance of 1,840 feet to be available for this take-off under the conditions which existed at the time.

At approximately 1145 hours CST on 7 October, 1973 a parachutist was fatally injured by impact with the ground following a free-fall descent at Batchelor Airfield, Northern Territory. Examination of the equipment after the accident revealed that the main parachute ripcord handle was out of its stowage, but the release pins had not been extracted from the cones. Tests indicated that a pull on the ripcord of at least 12.7 kilogrammes would have been necessary to open the parachute pack. There was no evidence to show that any attempt had been made to deploy the reserve parachute which was serviceable in all respects.

At 1001 hours CST on 12 May 1973, a Beech 35/C33 Debonair aircraft, registered VH-DHI, struck the ground near the top of a ridge three miles west-north-west of Myponga, South Australia. It was found that the aircraft had struck rising ground, some 750 yards from the coast near the top of a north-south ridge, while travelling in a westerly direction and in a substantially level altitude. The altimeter subscale was set to 1019 millibars, which was the current area QNH. An examination of the wreckage failed to reveal any evidence of a defect or malfunction in the aircraft which might have contributed to the accident.

On the afternoon of 27 October 1973 Fokker P27 Series 400 aircraft registered VH-TFM, operated by Trails-Australia Airlines was engaged on scheduled Regular Public Transport Plight NO. 1497 from Melbourne to Wynyard. It was under the command of Captain LI. Denheld with First Officer B.J. Widmer as the other flight crew member. The aircraft carried two hostesses and 28 passengers. In instrument meteorological conditions, and while offshore in the area between Wynyard and Devonport, the aircraft was reportedly flown at heights below the minimum altitude specified for IFR operations.

Mr. Pickard flew VH-TSF from Cambridge to the Andover agricultural airstrip at about 0630 hours in company with another Pawnee aircraft and pilot. The two aircraft were assigned to participate in a superphosphate spreading operation covering several properties in the Andover area. At about 0800 hours both pilots made a joint aerial inspection of the properties to be treated and they individually commenced operations at about 0835 hours.

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.