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Aviation History
1957
1957 - 0637.PDF
10 May 1957 641 IN THE DOCK Facilitating Airliner Maintenance FOR many years it has been customary to talk of ships in drydock, and for even longer of human beings in dock ofanother kind, both for examination; but only since the war has the idea of putting aircraft in docks for maintenance checkscome to be an accepted idea in this country. The first was built for B.E.A. Dakotas in 1948; in 1953 one was constructed for theCorporation's Elizabethans; in the following year Viscounts were "fitted"; a second Viscount dock, adjustable to take either the 700or 800 series, has been completed this year; and now the Britannia has gone into B.O.A.C. service with similar facilities. Acceptance by B.O.A.C. of the idea of such a dock, and itscoincidence in service with the aircraft for which it was designed, puts a final seal of success on the design and construction workdone in this field since 1948. What may then have appeared revolutionary has now become an integral part of maintenanceschedules; and in reducing turn-round times the docks are helping to increase utilization. Construction of those for the Corporationshas been carried out variously by W. and A. Williamson and Co., Ltd., in the case of the Check IV Dakota dock; the Heston Air-craft Co., Ltd. (the Elizabethan); B.E.A. (the Viscount—employ- ing direct labour); and six contractors jointly on the Britanniadock. Rodger, Setterington and Partners, of Western Avenue, London, W.5, have been design consultants on all the docks heredescribed. To visit the B.E.A. and B.O.A.C. engineering bases at L.A.P.is to get an instructive bird's-eye view of the different types of maintenance dock, for in those well-lit and well-warmed edificesare Pionair/ Leopards, Elizabethans, Viscounts and Britannias all snugly tucked away, with engineers carrying out their checks inconditions of comfort and accessibility. In basic principle the docks do not vary from the earliest to thelatest: they provide a permanent working platform in place of improvised ladders and trestles; as they are built to fit the aircraft,the risk of damage involved in moving loose equipment or tem- porary working platforms is practically eliminated; and electricaland other services can be brought efficiently and neatly to hand. The variations which occur (apart from those necessarily in-volved by the shape of the aircraft for which each dock is designed) are in simplification of construction; use of high-level platforms togive access to the top of the fuselage; introduction of an intercom system; and (in the Britannia dock) the provision of wheel-pits. When the first dock was constructed it was intended to be ofa temporary nature, for at the time Dakotas were thought to have only two more years' service; thus the main structure was formedof scaffolding connected by patent clamps, and this gave the appearance of a forest of columns. Since then the main structurehas been built of conventional mild-steel rolled sections, with the result that it has a much neater and less complicated appearance. The greater height of the more recent aircraft for which dockshave been designed has made it necessary to have a high-level platform, giving access not only to the tail unit but also to the topof the fuselage along its whole length. (This platform was first introduced with the Viscount; naturally nosewheel-undercarriagelow-wing aircraft have a greater overall height than those with tailwheels or high-wing layouts.) In the case of the Britannia (thetail fin of which reaches up to 39ft), it has been necessary to have an overhead structure partly supported from the hangar roof. Introduction of wheel-pits, so that undercarriage retraction testscan be carried out, is a modification peculiar to the Britannia dock, since the undercarriage bogie rotates through about 90 deg beforeretracting, and clearance had to be provided as an alternative to jacking up the whole aircraft by 3ft. The Britannia dock has also been designed to accommodate the100 and 300 versions of the aircraft, the latter being 10ft longer. Furthermore, a telephone system has been provided at the super-visory control point which can, if necessary, over-ride any local conversations. There are instruments at 12 different positions,each connected via a master indicator panel to the aircraft cockpit. There is so much to be said in favour of maintenance docks thatit is curious they did not appear on the scene earlier in aero- nautical history—perhaps because aircraft maintenance was amuch less complicated business than it is now; perhaps because war interrupted the progress of civil aviation. Only when an air-craft type is likelyto be in service for many years is it worthwhile constructing for it a dock which may cost up to £25,000. Suchan initial cost is high, but it should be recovered in two years on the saving in turn-round times. Four types of maintenance dock, showing their progressive develop- ment since 1948. From top to bottom they are for the Dakota; Elizabethan; Viscount; and Britannia.
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