page_title: 1950 Australian National Airways Douglas DC-4 crash
section_title: Investigation
hierarchical_section_title: 1950 Australian National Airways Douglas DC-4 crash / Investigation
caption_attribution_description: Screenshot of newsreel footage of Skymaster air crash near Perth, Western australia on 26 June 1950
context_page_description: On 26 June 1950, a Douglas DC-4 Skymaster aircraft departed from Perth, Western Australia for an eight-hour flight to Adelaide, South Australia. It crashed 22 minutes after take-off, 35 miles East from Perth Airport. All 29 occupants were killed in the accident; one initially survived, but died six days later. It was the worst civil aviation accident in Australia.
  As the aircraft flew eastwards over the outer suburbs of Perth numerous witnesses observed that it was flying at a lower altitude than usual for the daily Skymaster services, and at least one of the engines was running roughly and backfiring at regular intervals. In the minutes before it crashed, witnesses heard a number of different engine noises – sometimes operating normally, sometimes all engine noise ceased, only to be replaced by what was described as a very loud, high-pitched "scream". When the wrecked engines were examined many weeks after the accident a significant amount of corrosion product was found in the fuel system within two of the engines.
context_section_description: Three investigators from the Department of Civil Aviation began work at the crash scene the day after the accident. They found the Amana had crashed in a heavily timbered area on the Inkpen family property Berry Brow, on the easterly track between Perth airport and Kalgoorlie, at a point where the elevation was about 1,100 feet (340 m) above sea level. The aircraft struck the tops of tall gum trees while descending at an angle of about 15° below horizontal. Its speed at impact was estimated at 250 miles per hour (400 km/h). It crashed through large trees, breaking them off as if they were matchsticks, before impacting the ground violently and gouging a long, wide furrow. The left wing was torn away from the fuselage and then the aircraft broke up and burst into flames. Only the rear fuselage with the fin and rudder were not affected by fire. The wreckage trail was about 280 yards (260 m) long and 35 yards (32 m) wide. At the time of impact the Amana's left wing was lower than its right, suggesting it may have been turning left. It was heading north, not east towards Cunderdin. Investigators speculated that the crew may have been turning with the intention of returning to Perth airport; or they may have been preparing for a crash-landing in a large clear area to the north of the crash site.
  Possibly as a result of rough-running of one or more of its engines, the Amana was observed flying over Perth's outer-eastern suburbs at an unusually low altitude. No witness report was received from anyone along the next 16 nautical miles (30 km) of the Amana's track from Perth's outer suburbs to within 5 nautical miles (9 km) of the crash site. In the minute before it crashed, eight witnesses heard a large aeroplane in distress and reported unusual engine noise, including engine noise ceasing on at least one occasion, followed by the sudden return of very loud engine noise. This suggested that, on at least one occasion, none of the engines were producing power, followed by a resumption of power on some of the engines. The investigation team concluded that the Amana failed to reach its assigned altitude of 9,000 feet, and that it experienced intermittent engine problems of such severity that all engine power was lost on at least one occasion. Without power and with only one of its propellers feathered, a Douglas DC-4 loses altitude at a great rate, possibly as fast as 100 feet per second (6,000 feet per minute).
  Engines and propellers numbers 1 to 3 suffered substantial damage in the crash, but engine and propeller number 4 suffered much less damage. The investigators determined that at the time of impact, propellers 1, 2 and 3 were turning normally and their engines were producing power but propeller number 4 was feathered and its engine was not operating. There was also some evidence that action was taken by the crew to unfeather propeller number 4 in the moments before impact. None of the engines contained evidence of any internal failure prior to impact. All the magnetos were tested and the results indicated normal ignition was available to all engines up to the time of impact.
  Engine number 4 suffered only minor, external damage. It was dismantled by the investigation team in an attempt to determine why it might have been shut down by the crew. A substantial amount of corrosion product was found in the passages of the fuel flow meter on engine number 4. Western Australia's Deputy Mineralogist identified the corrosion product as magnesium hydroxide. This is a corrosion product formed by reaction of magnesium and water, suggesting the fuel passages had been filled with water in the months between the crash and the detailed examination of the engine. Charles Gibbs, an engine specialist employed by the Department of Civil Aviation, estimated at least 45 cubic centimetres of water must have been involved. Rain falling on the crash site before engine number 4 was removed could not account for this much water in the fuel passages. Gibbs first examined the fuel system of engine number 4 and discovered the corrosion about two months after
caption: Western Australian police examining the still-burning wreckage
exif: {}