In July, 1935, Sir Charles Kingsford Smith wrote from Sydney, N.S.W., stating that he intended to bring a Lockheed Altair to Gt. Britain accompanied by a USA Export Certificate of Airworthiness which he would present for validation under the reciprocal agreement between USA and Gt. Britain in order to undertake a flight from England to Australia. Before leaving America, however, the machine would be fitted with extra tanks for a special flight and the purpose of his letter was to request that provided the Export Certificate complied in every detail with the requirements of the agreement, the Air Ministry would grant a special British Certificate of Airworthiness which would enable him to obtain from the Australian Government on arrival in Australia a full commercial Certificate of Airworthiness, on removal of the extra tanks.

In reply Sir Charles was advised to obtain an Export Certificate of Airworthiness covering the machine with (a) its standard tanks (all up weight 5200 lbs) and (b) the extra tanks (all up weight approx. 7500 lbs), and containing a note of any special conditions attaching to the fitting of the latter. He was warned that special investigation of the extra tanks, with consequent delay, would be required if the Export Certificate did not cover them. The latter was confirmed by cable on 23rd. August 1935.

On 5th. October, 1935, the Vacuum Oil Co. Ltd., of Caxton House, Westminster, S.W.1. representing Kingsford Smith, presented for validation an Export Certificate and arranged for registration of the machine. This certificate was found to cover the aircraft (which was fitted with the extra tanks) at an all up weight of 5200 lbs, only on condition that the special tanks were either blanked off or removed, the engine changed to a Pratt and Whitney Wasp S.C.1., the airscrew setting changed and the rear cockpit sealed.

As no data regarding the machine in its modified state was available the Dept. of Aeronautics, Washington, was cabled as to whether their investigations would enable them to say if the machine was considered airworthy in that state for the contemplated flight to Australia. Their reply was to the effect that airworthiness could not be guaranteed but that they would be inclined to consider favourably the grant of a special restricted licence for the flight.

Their reply was not considered satisfactory for the purpose of issuing a special validation and Kingsford Smith was informed on the 12th. Oct. that either the tankage must be restricted as called for by the USA Export Certificate or an investigation of the modifications carried out at the Royal Aircraft Establishment.

Kingsford Smith then stated that he would be content with a compromise of an all-up weight of 6700 lbs. as granted in Australia as a special concession for the England-Melbourne Race in September, 1934, but the Dept. of Aeronautics cabled in response to inquiry that although the structure of the Lockheed was satisfactory at this weight the chassis absorption and flight performance was undetermined. In view of this it was considered inadvisable to permit flight at 6700 lbs.

It was eventually agreed with Kingsford Smith that the extra tanks could remain in the machine, although they were not to be filled to capacity, and the rear cockpit be left unsealed provided that the engine, a Pratt & Whitney Wasp S.E., was considered suitable for the one flight by the Dept. of Aeronautics, USA

In the confirmation that the SE engine, although not an approved type, was considered satisfactory for the special flight, a validation of the Export Certificate was granted at a maximum all-up weight of 5200 lbs., subject to the use of a specified airscrew setting and to the location of the centre of gravity position between defined limits. That the latter was possible with the extra tanks still fitted and that the petrol supply system functioned satisfactorily all (one indecipherable word) tanks were not filled, was checked over by an Inspector of the Aeronautical Inspection Directorate before the validation was granted.


The above is a facsimile reproduction of a document which appears in
National Archives of Australia
Series: MP 113/11 Item: VH/USB
Formatting and punctuation has been preserved.



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