Marville France

The Royal Canadian Air Force purchased two Comet Mk.1A for military transport use in 1953. Unfortunately, the RCAF Comets were withdrawn from service in January 1954 after a series of disastrous crashes in commercial service. We have obtained documentation which verifies flight activity of the RCAF Comets as late as 7 January 1954. The RCAF Comets were initially put into storage at de Havilland's Canadian factory at Downsview, Toronto in April 1954.

Unfortunately, the Comet had been let down by poor technology, not in its engines, but in the pressurised fuselage. Geoffrey De Havilland insisted on square windows to be different from the round portholes of the US competition and this proved to be the downfall of the design.

After much investigation and testing, it was found that the thin exterior skin of the aircraft was subject to metal fatigue. Stresses built up due to the pressurisation-depressurisation cycle during landing and take-off and cracks developed from the corner of one of the square cabin windows which lead to a catastrophic depressurisation; it literally blew itself to pieces in the air.

Following the Court of Inquiry most Comet 1A pressure hulls were re-built with heavier gauge skins and in addition their jet-pipes were "swept out" to reduce buffet. These changes were incorporated into the two RCAF 1As at Broughton, Chester, the first of which arrived on 24th May 1956 after a night-stop at Goose Bay. The modified 1As were designated 1XBs. The Mk 1XB had a reinforced structure and oval windows. Once the modifications were completed to the RCAF Comets, they were ferried back to Canada by de Havilland's chief test pilot John Cunningham and crew. The cost of the work was put at £142,000.

A total of 4 Mk 1As were upgraded to 1XB standard - two of which were those purchased by the RCAF.

The following table summarizes the relevant data of the two Comets which were purchased and used by the RCAF.