Because of its size the fuselage is divided into five sections. These are the nose, front centre section, centre section, rear centre section and rear fuselage. These sections, when bolted together, form the main fuselage. This is a stressed skin monocoque construction, built up with transverse channel section formers (frames), stiffened by fore and aft stringers that connect to the formers to provide the framework.
This framework is covered with alclad (a light aluminium alloy) sheet, the majority being 22 SWG but in some places 16 SWG. This is riveted to the formers and stringers with dome-head rivets.
The completed fuselage is made up of 51 formers, which are identified by numbers and letters. Formers 1-41 proceed aft from the first complete former in the front centre portion. Formers A-K (excluding letter I, which is not used due to its similarity to the number 1) proceed forward from that point.
The fuel system consists of separate port and starboard systems connected by a balance pipe. On each side of the fuselage, mounted in the mainplane, are three metal tanks, each fitted with an electric booster pump. Fuel is drawn by the engine pump or pumped by the booster pump from the tanks through non-return valves to the tank selector cocks. From here a supply is run to each engine.
The two inboard fuel tanks - the number 1 fuel tanks - hold 580 gallons each; the intermediate, or number 2 tanks, hold 383 gallons each; and the outboard, or number 3 tanks, holds 114 gallons each. Each tank is filled independently from the top of the wing.
On the BBMF's Lancaster only the number 3 tanks are fully filled and the fuel load never exceeds 1,000 gallons, with the rest of the fuel being evenly distributed throughout the other tanks. This is done to minimise fatigue and stress to the wings.
Each engine has its own independent cooling system. This comprises a header tank mounted behind the front cowling diaphragm, a radiator, attached below the engine, and a thermostat.
The system is operated under pressure, which is controlled by a thermostatic release valve at the top of the header tank. This valve limits the maximum pressure and provides a controlled escape of air, which allows for expansion at different temperatures. The temperature of the coolant is controlled by the thermostat, which allows the amount of airflow through the radiator dependent on the temperature. The coolant consists of 30 per cent glycol (AL3), and 70 per cent distilled water.
The oil system also has an independent system for each engine. This comprises an oil tank mounted in the engine sub-frame and an oil cooler mounted below the engine. The main feed pipe is taken from the filter in the oil tank and passes to the engine oil pump. The oil is returned via the oil cooler to the top of the oil tank. Each oil tank holds 37½ gallons of oil (OMD270).
Four Hamilton Standard three-bladed metal propellers drive the aircraft. These are the later wide-blade versions rather than the thinner blades that were mostly used during World War Two. Each propeller has the capacity to 'feather', which means that if there is an engine problem and the engine has to shut down, the individual blades can turn to 'fully fine' so that no drag is created.