LANCASTER I, III & X

ENGINE CONTROLS

20. Throttle controls

(i) Merlin XX, 22, 28 and 38 engiius. — Climbing boost +9 lb./sq.in. is obtained with the throttle levers (28) at the gate. On Merlin XX installations, and originally on Merlin 22, 28 or 38 installations, going through the gate gives a boost of + 12 lb./sq.in. at ground level only. A later modification to Merlin 22, 28 or 38 engines gives +-14 lb./sq.in. boost at ground level only with the throttle levers through the gate.

The boost control cut-out (32) gives +14 lb./sq.in. in M gear and +16 lb./sq.in. in S gear on all the above Merlins.

(ii) Merlin 24 engines. — Originally no boost control cut-out was fitted and no climbing gate. The fully forward position of the throttle lever gave +18 lb./sq.in. boost for take-off and combat. On these installations the automatic boost control does not allow the butterfly to open fully to maintain +9 lb. sq.in. boost up to full throttle height unless the throitle levers are progressively advanced to the fully forward position during the climb. However, a modification is now being introduced which overcomes this, and when this is incorporated a boost control cut-out is fitted which gives +18 lb./sq.in. for take-off and combat; the throttle quadrant is fitted with a gate at +9 lb./sq.in. boost, and the fully forward position gives +f 14 lb./sq.in. at ground level only, for take-off at moderate loads.

(iii) Merlin 224 engines. — The throttle quadrant is fitted with a gate are at + 9 lb./sq.in. boost; the fully forward position gives +14 lb./sq.in. at ground level only, for take-off at moderate loads. The boost control cut-out gives +18 lb./sq.in. for maximum take-off and combat.

21. Mixture control

(i) Merlin XX, 22 and 24 engines (Lancaster I).—S.U. carburettors and fitted. The mixture strength is automatically controlled by boost pressure, and the pilot has no separate mixture control. A weak mixture is obtained below +7 lb./sq.in. boost (+4 lb./sg.in on Merlin XX). The carburettor slow-running cut-outs are operated by closing the master engine cocks.

(ii) Merlin 28. 38 and 224 engines (Lancaiters III and X).—Bendix-Stromberg pressure injection carburettors are fitted. There is no pilot's mixture control, the mixttre strength being regulated by the power, so that an economical mixture is obtained below +7 lb./sq. in boost.

The carburettor idle-cut-outs, which are used in tuning and for stopping the engines, are operated by electro-pneumatic rams controlled by four two-position switches (11) or four pushbuttons (if Mod, 1753 is fitted) mounted on the pilot's panel above the engine starter buttons. When two-position switches are fitted the top position is the FNGINE RUN position, and the bottom position is the IDLE-CUT-OFF position; when pushbuttons are fitted, they have to be held in to keep them in idle cut-off.

Note.—If the pneumatic supply pressure is less than 130 lb./sq.in. (160 Ib./sq.in. when Mod. 1195 is embodied) it is possible to start the engines with the slow running cut-out switches in the IDLE-CUT-OFF position; then, when the supply pressure builds up the idle cut-off rams will operate and all four engines will stop.

22. Propeller controls. — The speed control levers (29) for the Hydromatic propellers vary the governed r.p.m. from 3,000 down to 1,800. The feathering buttons (19) are on the right of the instrument panel. For feathering and unfeathering procedure see Part IV, paras. 53, 54.

23. Supercharger controls

(i) On early Lancaster I aircraft the supercharger controls for all four engines are operated mechanically by one lever.

(ii) On later Lancaster I and on all Lancaster III and X aircraft, the superchargers are operated by eleclro-pneumatic rams of the single-action spring-return type. In the case of electrical or pneumatic failure the rams will return to the M ratio position. A switch, fitted to the pilot's instrument panel immediately below the engine speed indicators, controls all four engines simultaneously, and a red warning light beside it (25) indicates S ratio on the ground only (i.e. when the undercarriage is down).

24. Radiator shutters.- The shutters are automatically controlled when the switches forward of the flight engineer's panel are in the up position. When the switches are down the thermostatic control is over-ridden, and the shutters ore opened; this position should be used for all ground running, taxying and marshalling

24. Carburettor air-intake beat control — A single lever for the hydraulic operation of all four carburettors' warm air intakes is on the left of the pilot's seat.

When Mod. 1198 is fitted the control has 3 positions, COLD, WARM and HOT (emergy.). If the control is at WARM, air is then drawn into each engine through the warm air-intake inside the bottom engine cowling. When moved to HOT, a flap in the bottom engine cowling is opened by an electro-pneumatic ram and allows hot air to be drawn from the radiator to the engine. The WARM position may be used to prevent the formation of ice when flying in icing conditions, but this will reduce the range (see para. 49 (iii)).

If the flight is continued, instead, in COLD until carburettor icing becomes evident, the HOT position should then be used, but only until the ice his cleared.

If Mod. 1198 is not fitted, there are only two positions COLD and WARM, but the latter position should be regarded as having a similar function to the HOT position when the 3-position control is fitted, as air is drawn from the radiator to the engine through a hole in the engine cowling when the control is at WARM.

OTHER CONTROLS

26. Intercommunication. On Lancaster X, Bendix interphone station boxes are fitted. For inter-communication the selector switch must be set to INTER and the INCREASE OUTPUT control set full on.

26a. Fuel jettison control

The control for the jettison valves in No. I tanks is on the floor to the left of the pilot's seat, and is painted red. It is pulled up and turned anti-clockwise to jettison fuel.

Note.— The fuel jettisoning system must not be operated unless the pressure in the hydraulic accumulator is more than 650 lb. sq.in. When the flaps are lowered prior to jettisoning, the accumulator pressure should build up rapidly to 650-850 lb. sq.in. If, however, the gauge indicates a lower pressure, one of the main hydraulic systems should be operated momentarily, e.g. the bomb doors control should be moved to OPEN and then returned at once to CLOSED. This will cause the hydraulic cut-out valve to function and the pumps will build up pressure in the system. To ensure the most efficient operation of the jettiaon system the control valve should be opened as the rising pressure passes 650 Ib. sq.in., and a member of the crew should watch the gauge and signal the pilot at this moment.

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