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Aviation History
1942
1942 - 2328.PDF
506 FLIGHT NOVEMBER 5TH, 1942 THE HERCULES POWER PLANT stiffening gussets in the angle of the joint. Expanding bushes are fitted to avoid the necessity of reaming holes in the mounting brackets and the finger-plates after assembly. Each of these bushes consists of a split sleeve which fits into the holes in the bracket and finger-plate, and has an internal bore in the form of two opposed cones with their wider ends outermost. Cone-ends of similar taper fit into both ends of the sleeve, and the mounting bolt, which passes through the sleeve, draws together the cone ends, thus expanding the sleeve in the bracket and finger-plate bores. Circlips at each, end of the sleeve centralise it in the mounting bracket, and the mounting bolts are secured by split-pinned nuts. Mounting plates are welded in pairs at their after ends to further finger-plates to provide the four lugs by which the power plant assembly is attached to the airframe. Imme diately forward of these pick-up points, pressed-steel plates of Y-shape are welded to the mounting tubes for the attachment of the bulkhead, which is secured to each plate by means of sixteen 2 B.A. bolts with plain washers and self-locking nuts. The whole assembly of mounting ring and tubes is painted to protect it from corrosion. The Bulkhead The bulkhead is a single sheet of 20 s.w.g. stainless steel, stiffened by section members on its after face, and an L-section member round the outer circumference, the lip of which extends forward of the bulkhead. These stiffeners are welded or bolted in place, as are the various reinforcing plates which assist local rigidity at those points where the connections for the aircraft services are made. On the bulkhead are also carried union con nections for the various services, such as oil and fuel pipes, the airscrew pitch-control, the fire-extinguisher equipment, and the electrical junction boxes. All these connection points are located in standardised positions, which facilitates interchangeability. Thus when the power plant is installed, the connection points will be correctly situated to register with the pipe-lines, control-tubes, and wiring already fitted in the airframe. The standard layout of the bulkhead con nections includes the following: — Fuel supply. Oil supply. Oil refrirn. Oil-tank vent. Primer Boost gauge. Fire-extinguisher system. Cabin heater supply (when fitted). Cabin heater return (when fitted). Starter and main eiectrical junction boxes. Ignition cut-out. Pyrometer cable. Worth oil-dilution system (when fitted). Thermometer and pressure-gauge capillaries. Also electrical connection for fuel pressure transmitter. In order to meet the requirements of the various services and obviate any possibility of incorrect connections, each union of the standard equipment is of a different size or type from the others. The three largest unions are flanged, and each is secured in position by means of six bolts, which pass through a locking plate on the forward face of the bulkhead and the flange of the union body, being secured by plain washers and self-locking nuts. All other unions are secured by locknuts in the usual manner. •X, An earlier type of -'--a 1 power egg." The oil cooler is mounted below the cowling. On the starboard side of -the bulkhead an aperture is provided to accommodate the accessories connection panel. All pipelines required by the various additional accessoihr> are led to this panel, which, together with its fixing boffi^ and all connections, is an aircraft supply. Twenty fairing clips are fitted on the circumference of the bulkhead to support the atcessory compartment fairing. Fairing Supports The supports for the nacelle fairing consist of L-section brackets which extend rearwards and are covered with rubber bonded in place. They combine to form an almost continuous flange round the circumference of the bulkhead. Where the design of the nacelle is such that the fairing can not be carried directly on the supports, suitable brackets are made up and fitted by the aircraft manufacturer. Immediately aft of the controllable gill-ring, the power- plant engine mounting is faired off by means of four cowl ing panels which unite to form the shoulder cowling. Thev are riveted together in pairs to form two cowl units, one on the port and one on the starboard side. Two locating brackets which fit over the engine mounting ring are pro vided on each cowl unit; and each has a rubber block
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