page_title: De Havilland Express
section_title: Technical deficiencies
hierarchical_section_title: De Havilland Express / Technical deficiencies
caption_attribution_description: English: De Havilland 86A owned by Qantas Empire Airways, ca. 1940. This plane crashed at Brisbane on 20 February 1942. Pilot was Cec Swaffud.
context_page_description: The de Havilland Express, also known as the de Havilland D.H.86, was a four-engined passenger aircraft manufactured by the de Havilland Aircraft Company between 1934 and 1937.
context_section_description: This section is largely sourced from the book Air Crash, Volume One by Macarthur Job.
  Seriously lacking in directional stability, the D.H.86s were frequently in trouble. On 19 October 1934 Holyman's VH-URN Miss Hobart was lost in Bass Strait with no survivors. Flotsam that may have been wreckage from the aircraft was seen from the air three days later but surface ships failed to locate it in rough seas; the aircraft had effectively vanished. At the time Miss Hobart disappeared it was thought that an accident may have occurred when Captain Jenkins and the wireless operator/assistant pilot Victor Holyman (one of the proprietors of Holyman Airways) were swapping seats midflight. However, following the loss of Qantas' VH-USG near Longreach four weeks later while on its delivery flight, it was found that the fin bias mechanisms of the crashed aircraft and at least one other were faulty, although it is doubtful that this had any direct bearing on the accidents other than perhaps adding to the aircraft's lack of inherent stability. Further investigation revealed that VH-USG had been loaded with a spare engine in the rear of the cabin, and that one of the crew members was in the lavatory in the extreme aft of the cabin when control was lost. It was theorised that the centre of gravity was so far aft that it resulted in loss of control at an altitude too low for the pilot to recover (the aircraft was at an estimated height of 1,000 ft (300 m) prior to the crash).
  On 2 October 1935 Holyman's VH-URT Loina was also lost in Bass Strait, again with no survivors. This time a significant amount of wreckage was recovered from the sea and from beaches on Flinders Island. Investigation of the wreckage revealed a section of charred carpet on a piece of cabin flooring from just ahead of the lavatory door. It was thought possible that a small fire from a dropped cigarette had led to someone running aft suddenly to stamp it out – a sudden change in weight distribution that could lead to fatal loss of directional control while the aircraft was on a low-speed landing approach.
  On 13 December 1935, another Holyman DH86, Lepina, forced-landed on Hunter Island off northern Tasmania with the lower port interplane strut having "vibrated loose".  An investigation by the Australian Civil Aviation Board using stop-motion film of the wing in flight resulted in identification of wing distortion and failure under certain flight conditions.  Australian authorities in December 1935 required the installation on all Australian DH86 aircraft of a complete set of lift bracing in the wing rear spar and redesign of the bracing on the tail unit to provide greater redundancy.
  The Royal Air Force's Aeroplane and Armament Experimental Establishment tested the D.H.86A design in 1936 following three fatal crashes in Europe. It would be forty years before the report was published – one of the most damning indictments ever written on the design of a commercial airliner put into series production. The D.H.86 had been rushed from design concept to test flight in a record four months to meet the deadlines set by the Australian airmail contracts, and a lot of attention to detail had been ignored. It was a big aircraft for its power, and as a result very lightly built. There was poor response to control movements in certain speed ranges, the wings were inclined to twist badly if the ailerons were used coarsely and, most seriously, the vertical tail surface was of inadequate area. The result was an aircraft that, although quite safe under normal conditions, could rapidly get out of control under certain flight regimes.
  Although the control problems were overcome on later-manufactured D.H.86Bs by the fitting of a new spring in the elevator control and the fitting of auxiliary fins, the results of these tests do not appear to have been communicated to Australia and the D.H.86s already in use were never modified in this way to improve their safety. This lack of communication may have caused a number of later accidents, including at least one of two further fatal disasters in comme
caption: de Havilland VH-USE crashed at Brisbane on 20 February 1942.
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