Harold Wakefield engine course notes



Harold Wakefield engine course notes


Contains: preliminary engines, oil system, the four stroke cycle, timing, substantial notes on magnetos and carburettors. Followed by air-cooled engines (valves, cylinders, tappets, magneto timing, crankshaft). Liquid cooled engines (data), maintenance and notes including diagrams on various aircraft and engine systems. Starting procedures, general precautions, drills and procedures, picketing, heaters, fuels and refuelling. Continues with handling of aircraft and drills for starting, pre-take off, marshalling on return, nigh time, daily inspection of parachute, maintenance, RAF station structure, aircraft maintenance schedules, flight order book, forms 700, modification types, technical instructions, air publications list and other notes.






Multi-page notebook with handwritten entries


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[deleted] 1482321 A.C.2. Brackenridge. J.,
Hut 6, K Line,
4 T.T. Wing, 109 Entry [/deleted]
[indecipherable word] H H [deleted] R.A.F. [/deleted]
[deleted][underlined] COSFORD [/underlined][/deleted]

1582185 A.C.2. WAKEFIELD, H.E.
Hut No 4, C Line,
3 Squadron, 4T.T. Wing, 109 Entry,
Cosford, Nr Albrighton,

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[underlined] PRELIMINARY ENGINES. [/underlined]

[underlined] Types of Lubrication. [/underlined]

1/ [underlined] Wetsump. [/underlined]

In this type some parts are lubricated by splash and others by pressure. An oil pump is needed to lubricate by pressure. Also a sump is needed, bolted under the crankcase with an oil-tight joint between.

On Gypsy engine, a metal to metal joint. Keep joints clean and smooth. Cover with fitters blue and rub on surface table, then scrape of [sic] high spots.

[underlined] SUMP [/underlined]


Filter gauze cleans oil as it drops from pistons into sump. Aerobatic Screen prevents oil flooding cylinders when ‘plane is upside down.

[underlined] PRESSURE RELIEF VALVE [/underlined].


Excessive pressure forces spring open and oil escapes to sump. Opens at pressure of 45 lbs.

A by-pass valve in filter opens when filter clogs up, and the dirty oil is carried round engine, which is better than none.

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[underlined] OIL-PUMP. [/underlined]


Oil is drawn in by suction caused by rotating cogs. Outlet pipe is small [sic] than inlet so pressure is built up. Self-lubricating from oil it pumps.

A wet-sump has its disadvantages:- the oil never gets cooled properly.

VOLUME I A.P. ? } General Description.
VOL II Part I } General Orders & Modifications
Part II } Fits, Clearances & Repair Tolerances
Part II Airframes } Maintenance.
VOL III } List of spare parts, contains a checking list.

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2/ [underlined] Dry Sump [/underlined] :-


The scavenging pump has larger mesh than pressure pump to keep sump empty.

[underlined] Piston Rings. [/underlined]

Scarf Type – [drawing]
But [sic] Type – [drawing]
Step Type – [drawing]
Peg Type – [drawing]

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[underlined] The Four Strokes [/underlined].

[underlined] Induction [/underlined]:- Piston goes down, draws in mixture.
[underlined] Compression [/underlined]:- Piston goes up, compresses mixture.
[underlined] Power [/underlined]:- Piston driven down.
[underlined] Exhaust [/underlined]:- Piston goes up, forces gas through outlets.

[underlined] Crankshaft [/underlined].


[underlined] Valve Lead [/underlined]:- is the no. of degrees measured on the crankshaft by which a valve opens before TDC.
[underlined] Flame Rate [/underlined]:- time taken for mixture to burn.
[underlined] Dual Ignition [/underlined]:- gives quicker flame rate.

[underlined] Types of Gear [/underlined].

[underlined] Spur Gear [/underlined]:- [drawing]
[underlined] Spiral Gear [/underlined]:- [drawing]
[underlined] Worm Gear [/underlined]:- [drawing]

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[underlined] Timing [/underlined].

1/ Turn crankshaft in direction of rotation to 20° before T.D.C.
2/ Set clearance on no.1 inlet valve to .005”.
3/ Turn camshaft in direction of rotation until clearance is taken up.
4/ Mesh driving gears in this position.
5/ Check by turning engine in direction of rotation and noting position in degrees point when inlet valve just begins to open.
6/ Tighten and lock the driving wheel retaining devices.
7/ Set tappets to correct clearance.

[underlined] MAGNETOS and CARBURETTERS. [sic] [/underlined]

[underlined] S.U. Carburetters [sic] [/underlined]:- give a correct ratio of air and petrol and ejects it into cylinder. (11 – 15) of air to 1 of petrol, by weight.
Pressure at sea-level = 14.7165 lbs per [symbol]“.
The principle of the carburetter is the U tube, and the difference in pressure between the two sides.
When the speed of a gas is increased, the pressure decreases.


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This is only useful at one choke opening, Other than that one opening, to [sic] rich a mixture is obtained.

So a [underlined] diffuser [/underlined] is used to give correct mixture at all engine speeds except slow running.


As you climb the air gets thinner, so to [sic] rich a mixture is obtained. Therefore the petrol supply must be cut down. To do this an [underlined] Altitude Mixture Control [/underlined] is fitted to give a correct mixture at all altitudes.


As the aircraft climbs and the pressure gets less, the aneroid expands and pushes the needle into the jet and cuts down the supply of petrol, Thus we get a correct mixture at all heights.

As the pressure drops at height so we get a loss in power. [underlined] A Supercharger [/underlined] is fitted to maintain sea-level power at altitude. This pumps up the mixture to sea-level pressure. It can however only maintain sea-level pressure up to a

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certain height. It is driven at 6-10 times engine speed and can revolve up to 30,000 R.P.M.

When the engine is only running slowly there is not enough rush of air through venturi to cause any drop in pressure. So no petrol can be forced through. So we use a [underlined] Slow Running Jet [/underlined], and draw in petrol by using the drop in pressure caused by the air rushing round the butterfly.


When the large hole is uncovered by the butterfly, the engine switches over to the main jet once more.

However when the butterflies are opened the petrol doesn’t respond immediately as it takes time for petrol to be drawn from the carburetter. Consequently the engine has no petrol for a period and splutters and lags. This is known as [underlined] the flat spot [/underlined].

The flat spot is overcome by an accelerator pump. When the throttle is suddenly opend [sic] from the slow running position, the piston is automatically forced down and injects neat petrol through five holes in choke tube near the venturi. The inrushing air carries the petrol into the induction manifold.

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The pressure which the supercharger builds up in the induction manifold is called [underlined] Boost Pressure [/underlined] . It is measured in lbs. per [symbol]“.

[underlined] Rated Boost Pressure [/underlined] is the maximum pressure which manufacturers allow for running over indefinite periods.

[underlined] Rated Altitude [/underlined] is the greatest height at which we can maintain rated boost.

The maximum boost pressure permitted by the manufacturer for a period of not more than five minutes is [underlined] Maximum Permissible Boost [/underlined], used for take off, initial climb, and emergency.

The explosion of a weak mixture in the cylinder is know as [underlined] Detonation [/underlined]

When the pressure of a gas is increased, it becomes hotter, and detonation occurs. To avoid detonation we make the mixture richer. The extra petrol cools the combustion chamber and absorbs heat. For this purpose we fit an aneroid which

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is operated by boost pressure running through a pipe from the induction manifold to the aneroid. As the aneroid expands or contracts, according to boost pressure, it opens or closes the main jet by means of a needle.

In case a blow back from the engine smashes the aneroid, a [underlined] Safety Valve [/underlined] is fitted, which is closed by any sudden pressure striking it, thus protecting the aneroid.


On the bottom of the super-charger casing there is a [underlined] Volute Drain [/underlined] to drain away condensed petrol and assist the slow running jet.

To stop the engine we allow atmospheric pressure to enter the slow running chamber, by doing this we get rid of the difference in pressure and consequently no petrol is drawn through. To do this a [underlined] Slow Running Cutout [/underlined] is fitted.

The choke tubes are heated by hot coolants, and the butterflies by hot oil from the scavenger pump. These are heated to stop the mixture freezing as it strikes the cold surface when flying at great heights and the conditions are very cold.

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Two brass taps are fitted to get rid of air locks when filling up with coolant.

An [underlined] oil relief valve [/underlined] which opens at 25lbs per [symbol]“ is fitted. When the oil is cold it is no use for heating the butterflies, and when oil is cold it has a high pressure. We make use of this high pressure when it is cold to open the relief valve, thus the oil when cold goes in at the inlet and comes out by the outlet immediately, via the relief valve, without touching the butterflies at all.

When diving at full throttle the supercharger develops to [sic] much power as the ‘plane dives into denser air. So an [underlined] Automatic Boost Control [/underlined] (ABC) is fitted which by means of an aneroid automatically adjusts the throttle opening at all heights.


The progressive cam is fitted to give a definite boost pressure for a given throttle opening up to rated altitude. This is known as [underlined] Boost Control [/underlined].

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[underlined] Lubrication of Cross-Shaft [/underlined]:- As much anti-freeze oil as possible.
Lubrication of [underlined] Relay Piston [/underlined]:- 3.5 ccs. Anti-freeze oil.
[underlined] Relay Valve [/underlined]:- Close throttle, remove atmospheric union and pump in 3.5 ccs. of anti-freeze oil. Also oil the link work at inspections.

In American planes a [underlined] wobble pump [/underlined] is used to work up the pressure of petrol from carburetters. A red light warns when the required pressure is reached. The [deleted] hand [/deleted] engine pump takes over when the engine starts.

[underlined] A KIGASS priming pump [/underlined] is another method of starting an engine, the number of strokes required to start the engine, depends on the engine.

[underlined] Hollis Carburetter [/underlined]:- [drawing] } Throttle control settings.

[underlined] Stromberg Carburetter [/underlined]:- [drawing] } Throttle control settings.

[underlined] Under no condition must the mixture control lever be moved from the idle cut off position, when the engine is stationary [/underlined].

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[underlined] Magnetos [/underlined]:- Three basic types.

1/. [underlined] Rotating Armature [/underlined]:- gives 2 sparks per rev. up to a 6 cylinder engine. On an engine over 6 cylinders, the mag. would have to be driven to fast to give enough sparks. It is used as a hand starter mag. and also for testing purposes.

2/. [underlined] Polar inductor [/underlined]:- gives at least 4 sparks per rev. and is used on engines of 7 cylinders and over.

3/. [underlined] Rotating Magnet [/underlined]:- practically same as Polar Inductor.

In all mags. there are [underlined] Permanent Magnets [/underlined] which enable us to obtain electricity. The current always travels from N to S, and back again


The [underlined] armature coil [/underlined], which consists of laminated soft iron, wound round with a few turns of thick wire [deleted] and [/deleted] (the primary coil) and on top of that many turns of thin wire. (the secondary coil).

If magnetism is reversed through the armature coil a current of electricity is obtained.

[underlined] Terms used [/underlined]:- [underlined] Lines of force [/underlined], are the lines of magnetic attraction, collectively called [underlined] Magnetic Flux [/underlined], and area of the magnetic flux is the [underlined] Magnetic Field [/underlined].

If the current is flowing through the primary coil and is switched of by means of the [underlined] contact breaker [/underlined] (a mechanical switch in the primary coil to interrupt the flow of current.) we get a current sent through the secondary coil to the plugs.

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[underlined] Condenser [/underlined]:- is used to reduce arcing and sparking at the contact breaker points. It consists of sheets of tin foil seperated [sic] by sheets of mica, and assist the contact breaker to give a quick reverse of current and switch off.


[underlined] Distributor [/underlined]:- consists of a distributor rotor, and a distributor block.
[underlined] Earthing Switch [/underlined]:- in the cockpit

[underlined] P.I B.T.H. Type S.C.9-48 [/underlined]:- as fitted to the Pegasus gives 4 sparks per rev. The Direction of Rotation is obtained by looking at the front, and can be mounted on the engine in three ways, Spigot Face, Flange, Base Mounting. A metal distributor screen is fitted over the distributor. Most engines are started by a hand starter mag. which when turned by hand sends a current to the trailing brush [deleted] ing [/deleted] of the main mag. and therefore gives a late spark. Two leads are fitted to the mag. one from the hand starter mag. and one to cockpit switch. Ventilating holes are made in the distributor to clear the air of ozone which is present owing to the rotating brush striking the distributor points and becoming hot.

[underlined] A broken switch wire means a live magneto. [/underlined]

A safety spark gap is fitted to the secondary coil, which runs the current to earth if the plugs are damaged.

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At altitude the safety spark gap is no good so a heavier coil is fitted to withstand the heat of the electricity which is built up. S.S.G.’s are not in use now except on the rotating armature mag. which can’t have a heavy coil fitted. At height, no building up electric current is needed to jump the S.S.G. The current takes the least line of resistance, [deleted] on [/deleted] which is the S.S.G. and goes straight to earth without passing to the distributor.

Arcing:- particles of white hot material carried across gaps by jumping sparks, causing wear to points.

[underlined] Maintenance [/underlined]:-

[underlined] Contact Breaker Points of platinum alloy [/underlined]:- Wash in lead free petrol, wipe and dry. Level off pitted surfaces caused by arcing, by slipstone smeared with oil. If pitted badly, file first in case hardened steel plate [drawing] then finish off with slipstone and oil. Platinum alloy points won’t work in oil.

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[underlined] Contact Breaker Points of tungsten [/underlined]:- Will work in oil and stand up to heat. Tungsten is very hard, so it is possible to have convex surfaces on the points (without fear of wear) and the lubricating oil cannot then be trapped between the flat surfaces of the points. [drawing]

If slightly pitted, level off with fine emery cloth and oil, if badly pitted get new points from stores.

[underlined] Rocker Arm [/underlined]:- Check phospher [sic] bronze bush mounted on pin for wobbling, and lubricate round pin with 1 drop of winter grade engine oil every 60 flying hours. Check fibre heel for wear.

[underlined] Contact Breaker Spring [/underlined]:- Examine for security, cracking, discolouration, and for signs of blueing due to excess heat. Check for signs of varnish on spring, flaking. If varnish is flaking, clean off old varnish with dope solvent, revarnish except two ends. Check tension 2lbs [symbol] 1/4lb. using tension gauge and L-shaped peice [sic] of metal just behind contact breaker points.

[underlined] Cam Lubricating Pad [/underlined]:- 1 Drop of winter grade engine oil every 60 flying hours. If the new type impregnated pad in clip, is fitted, renew clip & pad every 60 flying hours.

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[underlined] Advance and Retard [/underlined]:- Smear spigot lightly with suitable grease. Check for wobble.

Adjust Contact Breaker points to .012” [symbol] .001.”

[underlined] Distributor [/underlined]:- Every 120 flying hours, wash in lead free petrol, then in hot water 75°C [symbol] 5°C, then rinse. Examine for cracks, if cracked, whole magneto withdrawn. If segments are pitted use emery cloth & oil to level off. Also for the brush on rotor arm. Check gap between brush and segments by [underlined] GO-NO-GO Gauge [/underlined] and check brush gap for wear by dummy distributor .011” - .019”.

Put 6 drops of oil every 60 flying hours in 3 wells.

Refer to Unit Maintenance Orders for lubricating.

For starting use hand starter mag. and time the current by the trailing brush on the main magneto.

[underlined] Leads [/underlined] High Tension (HT) {40 Strands T. Copper Wire
19 Strands Stainless Steel Wire.
Low Tension (LT) {23 Strands T. Copper Wire.

Do [underlined] not [/underlined] bend leads more than 4 1/2” radius or waterproof cover rips.

[underlined] Continuity [/underlined]:- [drawing] to see if current is flowing in one end and out the other.

[underlined] Insulation [/underlined]:- [drawing] to see if current is escaping through metal lead cover.

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[underlined] AIR-COOLED RADIAL ENGINES [/underlined].

[underlined] Pegasus II M3:- A 9 cylinder air-cooled radial engine.
Stroke 7 1/2”. Bore 5 3/4”. Swept volume (volume of cyl. from TDC-BDC) 1735 Cu”. Compression Ratio 5.5 - 1. Reduction Gear Ratio .5 to 1
Firing order 1,3,5,7,9,2,4,6,8. Petrol DTD 224./Oil DTD 109.

[underlined] Valve Timing [/underlined]:- Inlet Valve Opens 12° before TDC
Inlet Valve Closes 50° after BDC
Exhaust Valve Opens 65° before TDC
Exhaust Valve Closes 31° after BDC

[underlined] Valve Clearances [/underlined]:- Inlet .004”, Exhaust .006”.

[underlined] Cam Sleeve Operation [/underlined]:- Nickel chrome steel. The crankshaft sleeve is master splined to the crankshaft which drives the [inserted] cam [/inserted] sleeve driving wheel which in turn drives the larger wheel of the lay-shaft which is integral with the small lay-shaft wheel which drives the cam sleeve, in the opposite direction to the crankshaft and at 1/8 engine speed. It is lubricated at a pressure of 60lbs per [symbol]“, the oil is fed along 3 flats on the crankshaft to a groove in the crankshaft sleeve and from to the various drives and the cam sleeve itself.


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[underlined] Cylinders [/underlined]:-

Interchangeable if new. Set at 40° intervals. Steel barrel with Y alloy head. To fit head to barrel, head is heated to 320° and screwed to cold barrel. The head contracts and fits tightly, the head is made .0020” small [sic] than head. For extra security a steel ring is heated & shrunk over the joint. When the [deleted] l [/deleted] engine gets hot, the alloy head starts to expand but the ring keeps it tight. A copper washer forms a gas tight joint between the head & barrel, & the two are regarded as integral. Barrel is heavily finned. Flange at the bottom, with 8 holes for bolting to cr/case. Rubber washer between flange and cr/case. Spigoted to slide into cr/case. Scallops in spigot for con. rod clearance.


2 Phospor [sic] bronze plug adaptors are shrunk and dowled [sic] into head. 4 Valves to each cylinder. Valve seats of Nickel, Chrome, Manganese (NCM), hard wearing, heat resisting material. A small hole drilled in the top fin show that N.C.M. valve seats are fitted. If there are two holes it shows they have been reconditioned. Gas starter valve in phosphor bronze adaptor are now obsolete. The rocker box is held in 3 places by two trunnions and a tie-rod.

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[underlined] Valves [/underlined]:- Stems of KE965, nitrogen hardened, tulip shaped heads. Detachable steel caps are fitted on the stem, to prevent wear to valve stem. Hollow valve stem is filled with sodium salts which transfer heat from head to stem.

[underlined] Valve Springs [/underlined]:- Vanadium steel, in threes, wound in opposite direction to prevent fouling in case of breakage.

[underlined] Removing Reduction Gear [/underlined]:-

1/. Remove airscrew hub & place drip-tray underneath.
2/. Turn airscrew shaft until master spline is facing top of casing and mark with chalk in one or more places.
3/. Undo nuts around casing except 4, unscrew these to last two or three threads.
4/. Fit thread protector over airscrew shaft thread.
5/. Tap shaft with hide-faced hammer in several directions & fit fox wedges of wood between the two faces.
6/. Carefully remove reduction gear.

[underlined] Fitting Reduction Gear [/underlined]:-

1/. Lubricate with 1/2 pint of oil.
2/. Have master spline facing upwards.
3/. Offer up reduction gear & tighten up in opposites.
4/. Run round joints with .002” gauge.

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[underlined] Cylinder Changing [/underlined]:-

1/ Always remove no. 6 cyl. last and remove cyls. as opposites.
2/ No 1 Cylinder to be on TDC compression, undo base nuts of stack pipes & slide joint & rubber free.
3/ Undo lock nut on top of stack-pipe & slide pipe clear of crankcase.
4/ Remove nuts at base of push rods and also remove gas starter pipe.
5/ Remove nuts securing cylinder and pull cylinder clear of cr/case.

[underlined] Fitting Cylinder [/underlined]:-

Reverse the procedure, lubricate rubber ring in warm oil & lubricate cylinder walls. The number on the cylinder facing the airscrew. Check angle of attack & tappet clearance. Remove at least one sparking plug.

[underlined] Fitting Piston Ring [/underlined]:- Demand the correct type. Check the free gap, check the working gap using piston & cyl. Check ring for thickness, and check in Fits & Clearances volume. Fit ring using 3 pieces of tin.

[underlined] Angle of Attack [/underlined]:- Is the angle between the rocker arm & the valve stem. The ideal [symbol] of attack, giving minimum wear, is 90° when the valve is one third open.

[underlined] To Check Angle of Attack [/underlined]:-

1/ Place cylinder at TDC compression.
2/ Tighten down rocker on taking up tappet clearance.
3/ Loosen off one of the rocker arms.
4/ Place depth gauge in position and check gap between gauge and mushroom, if gap is between .000 - .020 the

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clearance is correct. If clearance is over .020, the push rod is to small.
5/ Remove same and check for bow, if bowed it may be remidied [sic] by tapping with a hide faced hammer.
6/ If rod [underlined] is [/underlined] to small fit a new one.
7/. The new one will be .060 oversize, check clearances, and to bring within the limit, remove steel cap from the end and file the rod.

[underlined] Setting Tappet Clearances [/underlined]:-

1/ Put cyl. at TDC compression.
2/ Set clearance (on exhaust) to [deleted] .060” [/deleted] .006” using two sets of feeler gauges.
3/ the clearance on the highest dwell and set all cyls. using the highest dwell.
4/ After setting No. 1 cylinder, move crankshaft 320° in the direction of rotation to bring dwell on the no. 9 cyl. Set clearance & carry on for all cylinders.
5/ Same procedure on inlet tappets.

[underlined] Magneto Timing [/underlined]:-

1/ Using P.P.I. find TDC compression on No. 6 cyl.
2/ Set engine to 35° before TDC.

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3/ Insulate mag. primary circuit with oiled silk & check C.B.
4/ Clip automatic advance and retard in the fully advanced position.
5/ Rotor opposite No.6 segment, points just opening.
6/ Offer mag. to engine & attach lamp & battery.
7/ Reverse engine a few degrees & then tap forward until the lamp goes out. (This should be at 35° before TDC.)
8/] Correct any error by adjusting on coupling. (1 Serration = 2.1° cr/shaft movement.

[underlined] Permissible error [symbol] 1°.

9/ Repeat procedure for other mag. & synchronise.
10/ Finally remove clip, oiled silk, and lock adjustor nuts, with split pins.

[underlined] Crankshaft [/underlined]:- In 3 parts 1/ Front half
2/ Rear half
3/ Tailshaft.

Made of nickel chrome steel drop forged. The rear web is split and fitted to crankpin, held by a maniton bolt.

[underlined] Connecting Rod Assembly [/underlined]:- Consists of one master rod & 8 articulating rods.

Material:- High tensile steel drop forged, H section. The articulating rods are held to the master assembly by wrist pins. Big end houses a freely drilled, fully floating, white metal bush. Gudgeon pin bushes are of gun-metal, shrunk & dowled [sic] into rod.

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[underlined] Reduction Gear [/underlined] :- Farman Epycyclic Bevel Reduction Gear. All wheels are of nickel chrome steel. At the rear a phosphor bronze ring is fitted and a magnesium ring is fitted at the front. The front thrust bearing is fitted to transfer the thrust from the airscrew shaft to the reduction gear casing & then to the engine, finally to the aircraft.

[underlined] Rear Cover [/underlined]:- Magnesium alloy, very light & inflamable [sic]. Rubber ring between it and volute casing, forming an oil tight joint.
On a Hercules the rear cover is called the auxiliary gear box.

[underlined] LIQUID-COOLED INLINE ENGINES [/underlined].

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Do not drain tanks below 3000ft.
Only drain one tank at a time.
An attempt should be made to drain 10 gall. from overload on homeward journey with a nose down attitude & about 15 to 20 degrees of flap.


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71 6 13 20 27 Mob


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cooler cooler cooller cooler

cooler cooler cooler

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Castor Oil used in air compressor (DTD72), in oil seal. Air bubbles through oil. The oil seal prevents leakage of air when compressor is not working. Air becomes impregnated with air as it passes through castor oil but oil is drained out as air passes through oil trap.

[underlined] Maintenance [/underlined] Daily Inspection. Take out inlet valve in compressor. Press plunger port on side of compressor. Oil either runs out or doesn’t. If oil runs keep plunger pressed till it stops running. If no oil runs out slowly pour in castor oil through inlet valve until it runs out port then close port. Castor oil stands heat without loosing its viscosity and oiliness. Always turn off cock before touching oil seal. Before undoing filter cap on oil seal, unscrew relief valve and let out compressed air. The compressor runs at half engine speed. If lack of pressure probably due to lack of oil, or to much oil, or to block of gauze at inlet valve. All pipes have a band painted round them to denote their purpose:- (Fuel – Red) (Coolant – Blue) (Oil – Black) (Compressed Air – Yellow) (Engine Starting – Green).

[underlined] Various Components on Oil Systems [/underlined]

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1/ [underlined] Oil Cleaner [/underlined]:- Two types low and high pressure.

[underlined] LOW PRESSURE [/underlined]:- 1/ VOKES HIGH PRESSURE 1/ TECALEMIT

[underlined] Vokes [/underlined]:- 2 Connections. Top & connections complete bolted to filter casing. Filter packed with corrugated material. Filter known as ‘element’. Pressure relief by springing the element. Oil passes from inside to outside of element. [drawing]

[underlined] Tecalement [/underlined]:- Inlet on the side, outlet on the centre. Plate on bottom removes to take element out. Oil passes from outside to inside of element. White cleaning element in Tecalement L.P. oil cleaner. Spring loaded relief valve at the bottom [drawing]

[underlined] Tecalemit High Pressure [/underlined]:- Inlet on the side, outlet on the side. Element is blue according to the RAF but to me its [sic] looks green. Relief valve fitted on top. Change element or remove and scrub with lead free petrol according to UMO’s.

2/ [underlined] Viscosity Valve [/underlined]:- is fitted to prevent damage to the cooler when the oil is cold & thick.
2 types, direct & pipeline fits on oil cooler [drawing]

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[underlined] Oil Coolers [/underlined]:-

1/ AM or Vickers Potts Straight fin
2/ AM or Vickers Potts U fin
3/ Serck rectangular.
4/ Serck drum.
5/ Robertson

[underlined] 1 & 2 [/underlined] Cleaned internally & externally with parafin [sic] using if necessary a stiff wire brush. Internally clean by flushing with parafin in reverse direction of flow. Clean pressure relief valve with dope solvents if can’t clean with parafin. (St. & U fin types)

3/ Serck rectangular type usually has viscosity valve fitted. Smaller hole inlet, larger hole for outlet as oil gets thicker as it cools. If stones get stuck in tubes push out with a stick or rod in opposite direction to airflow.

4/ Serck Drum (up to date used on Spits, Wimpeys etc), usually fitted with a relief valve. Has double casing, oil goes in inlet, round between the two casings to the bottom, and then through openings into honeycomb and out at the outlet. [drawing] Clean with parafin. Temporary repair by a long bolt, fibre washer, steel washer, nut.

5/ Robertson:- Is used with a viscosity valve, oil flows [underlined] through [/underlined] the tubes in this type. [drawing] Inlet on one side outlet on opposite side. Two holes on inlet size [sic]. Large hole to small tubes. Small hole for by pass through large tubes when oil is cold & thick. Cleaned inside & out with parafin.

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If one of outside tubes breaks, snip off & plug up ends with rubber plugs. If an inner tube, remove end plates & plug up defective tube with rubber plugs. Usually used on sea-planes and flying boats.

[underlined] Oil Tanks [/underlined]:-

Oil is cold
A is open
B is closed
[boxed] Oil is hot
A is closed
B is opened. [/boxed]

Air vent fitted to breather on rear cover.

A two way vent valve is fitted to air vent tube to prevent oil gushing through when plane is of [sic] level. +4 lbs pressure assists thick & cold oil to get from tank to pressure pump, when gravity may not be enough to draw the thick oil down. Fuel & oil tanks almost same. Made of sheet metal, Alclad, Duralumin, Tinned Steel, Stainless Steel. Baffle plates inside to prevent fuel surging about, as 100 gals of fuel bashing against tank sides would be no joke. Alloy tanks anodised against corrossion [sic] & then painted. Paint over immediately if varnish is scratched off, with seaplane varnish or lanolin. Light alloy tanks are welded, steel tanks riveted [underlined] generally [/underlined].

[page break]

De Bergue rivets with petrol resisting fibre (petrolite & langite) [drawing]. Flush rivets. If De bergue rivet works lose [sic] repairable by De Bergue’s special rivet repair bolt, fibre lined.

[underlined] Leak testing on small tanks [/underlined]. [inserted] Remove tank from aircraft [/inserted] Blank off all outlets except one & fit Schrader Valve to that one then with foot pump, pump up pressure of 2 – 3 lb [symbol]” inside tank. Immerse in a tank of water & look for bubbles.

[underlined] Leak testing on large tanks [/underlined]. remove from aircraft. Fill to 1/10 of its capacity with parafin. Blank off all outlets. Then paint inside of tank with whitening mixture (meth & french chalk). Shake tank and a stain shows where parafin leaks out.

[underlined] Temporary Repairs to tanks [/underlined]. To [sic] types. Repairs above fuel-line & below fuel-line. If above can usually be repaired without moving tank. If above line repair with some chewing gum, plastic wood, asbestos string & fish glue. Tapered rubber plugs for bullet holes, notches on plug to obtain good grip. Nut & bolt with a peice [sic] of rubber tubing [drawing].

If below water line use swivel-headed bolt with fibre washer of petrolite or langite & steel bolt. [drawing]

A.V.R. Sheet Snipper [drawing]

Solder on star-shaped patches, but tank must be left empty for 24 hrs & have an air blast going

[page break]

it for 8 hrs. File hole level & catch filings on a greasy rag. Stearin flux for soldering aluminium.

[underlined] Filter [/underlined]

[drawing] Oil goes in & comes out of the sides.

[underlined] Coolant System [/underlined]:-


[underlined] Header tank [/underlined] usually made of brass or tungum [sic] owing to their resistance to corrosion. Two way vent valve fitted to prevent loss of coolant due to evaporation.

[underlined] Thermostat [/underlined]. Three connections. Inlet at top, outlets at side & bottom. Thermostatic bellows inside filled with quick boiling fluid. The hotter the coolant going through going through the quicker the bellows expands. The bellows operate a sleeve which operates valves open the outlets. When the coolant is cold rad. valve closed, by pass valve opened, so goes direct to engines. Coolant 85°C before valve to radiator [inserted] begins to [/inserted] opens and by pass valve [inserted] begins to [/inserted] closes. Both valves open & close proportionately. At 105°C by pass fully closed

[page break]

and radiator valve full open. Thermostat controls minimum temperature & gives a quick warm up for starting by shutting of radiator. If thermostat has yellow bound [sic] round pure glycol must never be used.

[underlined] Radiators [/underlined].

1/ Honeycomb:- [drawing] 2/ Gallay [drawing]

[underlined] Emergency repairs [/underlined]:- by means of leak stopping compound. Drain out glycol fill with water add compound warm up. Then drain water & replace glycol.

[underlined] Temporary repair [/underlined] Use special blanking plate for Gallay and long nuts & bolts. Have to use plate on Gallay to because of three or two tubes joined together.

To clean it run hot water through in reverse direction of flow, if that isn’t sucesful [sic],

1/ Fill with hot water & allow to stand.
2/ Then flush through with hot weak caustic soda in reverse direction of flow.
3/ Flush out with warm weak mixture {Phosphoric Acid - Chromic Acid} reverse direction
4/ Flush with hot water, reverse direction

[underlined] Aviano Coupling [/underlined] rubber, metal covering, jubilee clip used on the thermostats & cooling system.

[page break]

[underlined] Fuel Filters [/underlined].

1/ R.A.E. 1/ Short, [inserted] Medium [/inserted] Long, 3 sizes, exactly the same.
2/ ENOTS. Inlet on the side, outlet on the top.
Spring loaded filter in cylinder. Flows from outside to inside.
2/ Enots. Inlet on side, outlet on top. Two filters one round the other. Oil into inside filter and oil goes through the outside filter and [inserted] all [/inserted] the clean oil is drawn from the space between the two filters.

[underlined] Priming Pumps [/underlined]:- 1/ Ki-Gas
2/ Semi-Rotary or Wobble.

1/ Ki-Gas. Two connections, petrol drawn into pump [deleted] and [/deleted] through inlet and pumped out through outlet. Ki-gas pump is used for pumping petrol straight into cylinder head. When not in use screw up tight.
2/ Used for priming the whole fuel system, when engine starts keep pumping until engine is going fast enough for engine driven fuel pump to take over. Relief valve fitted to relief any excess pressure of fuel pumped in.

[page break]

[underlined] Sparking Plugs [/underlined]

Only 3 sizes in the R.A.F. Determine the size by the crest diameter of the part which screws into engine. 18mms 14mms & 12mms. Three makes KLG, Lodge, & A.C. Sphinx, make all three sizes each.

High Duty Plugs are used in supercharged engine, [deleted] with [underlined] mica [/underlined] insulation [/deleted]
Low duty plugs are used in unsupercharged engine,

Insulation used:- Mica & sintered aluminium oxide (SAO) or Ceramic, on high duty plugs.
Mica only used on low duty plugs.

[drawing] [deleted] [drawing] [/deleted]


Centre electrode of a high duty plug much larger than
centre electrode of a low duty plug, because of extra heat in supercharged engine, larger electrode gets rid of extra heat. If a big electrode was put in low duty

[page break]

plug, oiling up would occur. Spark gap .012 - .015”


Plugs are screened to prevent wireless interference, if wireless aboard. Metal screen coated with mica inside.

Maintenance:- 1/ Strip Plug. Mark [deleted] cel [/deleted] clearly with red paint if U.S.
2/ Wash in lead-free petrol, if can’t clean carbon off, sand blast [deleted] body of plug [/deleted] [inserted] central electrode [/inserted] but fit disc to prevent damage to plat. alloy electrodes. If lead deposit on micra [sic], mount in lathe and clean off with 000 emery cloth. Then polish it with paste of jeweller rouge & oil or crocus powder & oil. Skim discharge surface in lathe with special tool. Allowed to take [deleted word] .012” off, measure with special guage [sic].

Carry out electrical check on [inserted] insulation of [/inserted] the central assembly.
Mica plugs strip & clean every 30hrs.
S.A.O. if this passes gas test, & spark plug test O.K. usually require cleaning every 60hrs.

[page break]

[underlined] Propellers [/underlined]:- (AP 1538)

Purpose:- to convert the power developed by the engine into “Thrust”. i.e. forward movement of aircraft. Check blade angle at Blade Angle Station, roughly 2/3 of distance out along blade on average size prop 42” from the centre.

Blade angle lessens towards tip to spread the load over the whole blade.

[underlined] Pitch [/underlined]:- the distance the prop ought to move the aircraft forward in one rev. of the prop.

[underlined] Right Hand Prop. [/underlined] one that screws forward right handed

[underlined] Tractor Prop [/underlined] one that pulls from the front.

[underlined] Varieties of Prop [/underlined]
Fixed Pitch – Variable Pitch V/P [symbol]
a) 2 pitch controlled
b) Constant speed controlled (CSC)
c) CSC Prop. Feathering type

[underlined] Pitch Range :- [/underlined] this applies to V/P Props. only. It refers to the number of degrees which the blades alter from extreme fine to extreme C.P. or the difference between C.P. & F.P. angles.


[page break]

10° V.P. De Havilland Prop. (2 Pitch controlled) Movement of the pilots control in the cockpit will operate a control valve on engine. This allows oil from lubrication system of engine to pass at normal oil pressure e.g. (60lbs [symbol]” ) into the prop. cylinders. The oil pressure forces the [underlined] cylinder [/underlined] forwards: this transmits motion (through the counter weight brackets) to the blade roots. The blades are partly rotated on their bearings (the spider arms) & thus brought to a smaller blade angle giving fine pitch.

In brief:- Control levers back, cyl. forward, blades at fine pitch. (For take off & climb)

Returning blades to coarse pitch’.
Movement of control lever to forward position causes the control cock to open a duct to engine sump at the same time shutting off the pressure oil from engines.

Centrifugal force at the counterweights will now cause the cyl. to move back changing blade to C.P. The oil from the prop. cyl. being returned while doing so. The pilot has no choice other than one or other of these two pitches. C.P. is used for normal flight.

[page break]

[underlined] Names & purpose of some of the parts [/underlined]

[underlined] Spider [/underlined], nickel steel, is the centre of the prop. takes rotary thrust of Eng. & forward thrust of blades. (2 main differences {a parallel spline - a taper spline }

[underlined] Barrel [/underlined], nickel steel, boxes in the parts & in particular retains the blades on the spider.

[underlined] Shim Plates [/underlined], in some cases steel, in others Oilite; purpose is to give the correct amount of tightness (Torque Loading) of the blades.

[underlined] Index Pins [/underlined], of roller steel, to key the counter-weight brackets to blade roots.

[underlined] Co-Wt Brackets & Weights [/underlined]; steel, provide link between cyl. & blades.

[underlined] Pitch adjusting screws & nuts [/underlined], steel, provide a means of reducing pitch range.

[underlined] Piston [/underlined], of steel, holds the prop. on shaft, provides a base for piston leathers.

[underlined] Piston Leathers [/underlined], soaked in engine oil for 2 1/2hrs. at least before assembly. The front leather holds compression, the rear one acts as a guide ring. An al. alloy packing ring is fitted between the 2 leathers.
Light grease for co-wt. bearings.
Heavy grease for main blade bearings.

[page break]

[underlined] Snap Ring [/underlined]:- Spring Steel, acts (with the front-cone) as an extractor for the prop. It serves [underlined] no [/underlined] other purpose.

[underlined] Front Cone [/underlined], steel, centres the spider on shaft, with the snap ring it acts as extractor for prop.

[underlined] Rear Cone [/underlined]. (if fitted) bronze, is part of engine not prop. helps in location of spider on shaft.

[underlined] Locking Plate Steel [/underlined], fastened to spider by 3 S.S. Split-pins locks the piston.

[underlined] Ring Nut [/underlined], steel, retains the leathers & packing ring on piston.

[underlined] Cylinder [/underlined] Al. alloy, is the sliding member, cap & gasket keep it oil-tight.

[underlined] Barrel-bolts [/underlined], hold the barrel together.

[underlined] Installing a De Havilland 10° Prop. on Shaft [/underlined].

Place A/C in rigging position (if possible) chock wheels.
Weigh tail. Inspect shaft splines. Smear with Whitmores compound. Place master spline of shaft at B.D.C.
Remove Piston Leathers from [deleted] piston [/deleted] prop.
Put slings round nos. 2 & 3 blades, leaving no.1. to hang down. Remove protecting cap from shaft & hoist prop. up level, with it. Slide prop on, engaging master spline & start the thread of piston on shaft. Tighten up with correct force (950lbs/ft for size 4 prop. Check the track (tolerance [symbol] 1/16” new or [symbol] 1/8” overhauled prop.) Lock piston to spider by means of

[page break]

locking plate & 3 S.S. split pins. Assemble the gaskets & cyl. cap together screw up reasonably tight & lock with circlip. Check over all locking devices on exterior of prop. See that blade bearings and co-weight bearings are lubricated with grease.

Pitch change jack used for changing pitch, when stationary.

Prop is now ready for [underlined] running check [/underlined]

[underlined] Basic Setting:- [/underlined] can only be done with the prop in a completely dismantled state and [deleted] s [/deleted] needs to be done in conjunction with a Blade Angle Checking jig. The same jig is used for pitch adjustments. Torque loading check also requires the use of a special jig-up adjustment of the torque loading entails stripping the prop. and the fitting of thicker or thinner shim-plates to suit. When a basic setting has been made the figure is stamped on the lead plug in the counterweight. Reference to this and the positions of the stop nuts on the pitch adjusting screws, will show the pitch settings of the individual prop.

[underlined] Note [/underlined]:- the basic & pitch settings for any type of aircraft will be called for in AP 1538 & are strictly kept to.

Rear leather is deepest; has bevel on outside. Cup side goes to rear of piston. Packing ring between two leathers goes in with large radius toward rear leather. Front leather shallowest, level on inside edge, goes on piston cup to front. [drawing]

[page break]

[underlined] Samson extractor [/underlined]:-

To use extractor, remove cyl. piston & front cone from prop. Screw dummy piston tight on shaft. Substitute the 6 long studs for the barrel bolts & assemble nuts at rear of barrel. Place plate on front. Assembly [sic] the 6 front nuts & screw up evenly. This frees the spider.


[underlined] 20° De H. Prop. [/underlined]

The basic difference between this & the 10° prop. (apart from the increased pitch range) is the use of the two strong springs. Their purpose is to help the centrifugal force to return the cylinder to the coarse pitch position.

The springs are compressed behind the piston head (by the oil pressure) whilst the cyl. moves to F.P. position. Then as soon as the oil pressure is released by the Control Cock or Constant Speed Control Unit, the springs exert their pressure to move the cyl. rearward.

[page break]

Different parts in cyl. assembly:-
2 Springs
Spring retaining bucket & circlip
Draw bolt. Cap nuts & its retaining circlip
Piston head & its 16 retaining screws.
1 Small steel washer & 1 copper oil sealing washer
In this prop. there is [underlined] no [/underlined] piston leather packing ring or ring nut.


[underlined] Installing 20° Prop. on Shaft. [/underlined]

Proceed the same as for 10° until prop has been tightened on shaft & locked by the 3 split pins.

Then:- Assemble drawbolt, bucket, circlip & springs in piston.
Place the leathers correctly in position on piston
Assemble & tighten the piston head with 16 screws & lock them.
Place the small steel washer on draw bolt
Assembl [sic] cyl. gasket & cap & lock with large circlip
Assemble oil sealing washer, cap nut & small circlip.
The rest as for 10° prop.

[page break]

[underlined] Running Faults 10° or 20° props [/underlined]:-

Oil Leaks: liable to occur in 10° & 20° types at:- [symbol] Front cone packing washer. - Rear of cyl; caused by faulty front leather. - Cyl.Cap; slack or faulty gasket.

also in 20° prop at the cap nut through lack of, or faulty Oil Seal Washer.

Sluggish pitch change or failure to change pitch. caused:- [symbol] Lack of oil pressure due to faulty controls. - Broken or clogged pipes & ducts - Faulty front piston leather. - Severe oil leakage. - Broken ball [deleted] b [/deleted] roller bearings.

Normal time taken to change pitch about 5 secs.

Vibration:- caused by. [symbol] Blades out of pitch, track & balance. - Blades loose in barrel. These cannot be rectified, with prop. on engine & it must be removed. - Prop loose on shaft:- - Unequal quantities of grease on blades [symbol] Can be rectified on engine.

[underlined] Daily Inspection :- [/underlined] Check blades for cuts, cracks or any other damage. Test for looseness of blades and looseness of prop. on shaft. Inspect for oil leakage.

Run engine (whilst warm) to check pitch change.

[page break]

Checking mags. with C.S. controlled [deleted] pitch [/deleted] prop.

Two classes of engine { Class I - Class II

Class I are allowed to do full revs & boost on the ground
class II are [underlined] not [/underlined] allowed to do full revs & boost on the ground

[underlined] Class I engine [/underlined]:- With prop. & throttle levers fully forward the mags. are checked in the usual way.

[underlined] Class II engine [/underlined]:- Prop. control lever at Take Off revs position.
Throttle control lever at Take Off boost position.

Steadily close the throttle until revs. begin to drop.
Leave the controls at that. Switch mags in the usual way.
Caution:- Do not run the engine longer than needed, & watch temperatures whilst doing so.

[underlined] Controls [/underlined]:-
Teleflex:- Flexible type. (Greased with anti-freeze grease)
Sloetube:- Ball & socket joints, ball crank levers & light tube (anti-freeze grease at ball joints; not at ball crank bushes

[underlined] Exactor Control [/underlined]:- Hydraulic & spring mechanism.

[page break]

[underlined] Pesco Vacuum Pump [/underlined]:-

Mounted on and driven by the engine. Purpose of it:- to draw air through navigation instruments. Rotation can be either way to suit the engine: but the instruments & relief valve must be connected to the suction (inlet) side; & the oil seperator [sic] to the exhaust side of the pump.

Lubricating oil from engine system is fed at pressure into the pump:- in some cases by external pipe to pump body. In other cases through Ducts in the Pad by which pump is fixed on engine. The oil is passed out with the air at the exhaust. This is connected to the oil seperator {sic], which reclaims the oil & allows the air to pass to atmosphere.

Connections to pump [symbol] Air inlet - Air outlet - In some cases an oil pipe connection.

Maintenance:- Check security on engine
Examine the pipe connections.
See there is no dirt in the gauge of the suction relief valve. The suction relief valve is fitted to break down excessive depression, it lets air in when it operates.


[page break]

[underlined] Hydraulic Pumps. [/underlined] The purpose of all these is to pump hydraulic fluid through one or other of the aircraft hydraulic systems. To operate retractable undercarriage, gun turrets, etc. 3 types dealt with in class; Savery Pump, (fitted to Lockheed Hudson)

[underlined] Savoury [sic] Pump [/underlined]:-

Has 3 main connections & drain pipe. The inlet (gravity) has large union. The pressure outlet connection is the smaller union close by inlet. On the other side of the pump by the relief valve is the by pass connection, through which excess fluid is by passed to tank. The relief valve housed in the cap-nut on the pump body lifts at 1850 lbs [symbol] ”. The drain pipe from the pump mounting flange must project downwards.

[underlined] Savery Maintenance [/underlined]:-
Check security of pump on engine.
Check hose connections on pump.
See that there are no fluid leaks.

[underlined] Dowty Pump [/underlined]:- A single stage gear type.
The relief valve in pipe system: not in pump.
2 Connections marked inlet & outlet.
Will build up 1000 lbs per [symbol] “ pressure.
[underlined] Maintenance [/underlined]:- Security.

[page break]

[underlined] Bristol 3 stage type [/underlined]:-
Gear type; comprised of 3 pairs of gears in seperate compartments. The pressure being stepped up in each section. Inlet connection is the larger one under the body.
Outlet connection is the smaller at the end of the Pump.
Builds up 680 lbs per [symbol] “ pressure. Relief valve in pipe system.
Drain connection from mounting flange (points down)
[underlined] Maintenance [/underlined]:- As for the Dowty.


[underlined] Electrically Driven Immersed type [/underlined]
[underlined] Fuel Pump [/underlined]:-
2 Models [symbol] E P I Works at 24 volts. - E P II Works at 12 volts.

This is [underlined] not [/underlined] an engine driven pump. It is fitted partly immersed in the fuel in the fuel tank. Driven by current drawn from battery in aircraft.

Can be used either as main or auxiliary pump.
Periods at which it must be taken out of tank & exchanged.

[page break]

240 hrs. if used as main pump
500 hrs. if used as auxiliary pump.

Fuel flows into pump through grid in bottom (which must be kept at a minimum distance of 1/4” from bottom of tank) it flows out at union connection at top of pump.


[underlined] To fit pump in tank [/underlined]:-

Remove any blanking covers from pump. Push it to bottom of tank & draw it back 1/4”. Line up the pipe connection, but do not couple up yet. Tighten down the gland nut & lock it with spring clip. Fill the oil chamber in top with DTD 109. Replace filler cap & lock it.
*Run pump a moment to clear it of any possible dust etc. Couple up the outlet connection & lock it.
* [underlined] Note [/underlined]:- Testing pressure. Pump should give 10 lbs per [symbol]“ pressure if it will not do so replace it with another.
This should be done during installation before connecting up.

[page break]

[underlined] Maintenance [/underlined]:- Switch on & run pump to test it.
See there are no leaks at gland.
See the outlet & plug in connections are secure.
[underlined] Daily [/underlined]:- see that the oil chamber is full up.

[underlined] Graviner Automatic Fire Extinguishers. [/underlined]

Methyl Bromide, a gas compressed into a liquid state.
Mark II Automatically controlled, out of reach of air-crew.
Mark [deleted] II [/deleted] I Automatically [underlined] and [/underlined] hand controlled.
Placed in various positions in aircraft.
Four operating switches even if only one extinguisher fitted.

Impact switch - Gravity [inserted] ineffective [/inserted] when flying - Heat when flying - Press Button when flying [symbol] 4 Switches

The switches and their wiring are in the electricians charge.
Maintenance:- by Flt. Mechs:- Periodically as per Unit Maintenance Orders. Weigh the containers to find out if their contents have leaked. The [underlined] empty [/underlined] weight of each container is always stamped on its handle. When container is marked ‘A’ its contents should weigh 6 lbs. When the gross weight proves to be less than it ought to be the complete container must be exchanged for a fresh one.

[page break]

When the extinguisher is known to have acted its brackets must be examined for damage & distortion.
When cleaning piping the ends must be free & the pipe blown out with compressed air.
The holes in the pipe must not be enlarged.
The nozzle at the end of pipe (in some cases only) can be disassembled & cleaned & the hole poked through with a 1/16” drill or wire.
Caution:- When removing the mark I type container from its brackets take care to depress the catch & lift out the container carefully otherwise it will automatically discharge its contents. In case of fire snatch it out of bracket.

[page break]

[underlined] Preparation of New Engine For Installation [/underlined].
When returned from makers.
1/ Check for defficiency [sic].
2/ Check for damage, continuity & insulation.
3/ Check contact breaker assembly, spring, rocker arm & points etc & lubricate, also set the points to correct clearance.
4/ Check all connections for security. Clean filter in lead-free petrol. Drain sump, drain bottom cylinders.
5/ [underlined] Fuel system [/underlined] check by tightening, locking.
6/ Check valve springs, & grease with black grease & lubricate nipples with anti-freeze grease. Check push rods for security.

[underlined] Preparation of Aircraft for Installing New Engine. [/underlined]
1/ Check bearer plate for cracks, & alignment. Check alignment by spirit level, straight edge & plumb line.
2/ Check controls, (counter-shafts, lay shafts, link work) for cracks, security & lubricate.
[deleted] 3/ [/deleted] 1/ Bearer Plate
2/ Controls
3/ Oil System
4/ Fuel System
5/ Instruments
6/ Coolant System
7/ Ignition

[page break]



Capillary tube must be clipped 12”. If rolled, roll must be at least 6” in diameter.

Thermometer tested with master thermometer.

[page break]

Fuel press. gauge capsule must be kept dry. This is done by fitting a fuel trap.

Special jig used for testing oil pressure gauge.

[underlined] Ignition system [/underlined]. Check switch box for security, & check switches. Check leads visually. Check for continuity. Insulation switches on, continuity switches off.


[underlined] Fuel System [/underlined]

Gravity tank for emergency & starting.

[page break]

[underlined] Throttle Adjustment [/underlined]:-


Check for security, freedom of movement, full travel, corrosion, lubrication.

5° error allowed on ’Take Off’ side, to get take off revs.

When installing new or reconditioned a British radial Pump 1/2 gal. of oil at 60° in B.G. connection, round about normal working pressure.

4 gunfuls [sic] in nipples between 1 & 2 cyls.
4 gunfuls [sic] on supercharger gears.
This is done when 1/ Installing
2/ Engine stood for 5 days.
3/ Or Extreme cold weather.

[page break]

[underlined] Starting Procedure. [/underlined] Away from hangar, on level ground, not gravel ground. Into wind. Chock wheels, & brake (if fitted). Fire extinguisher, nearby. Man in cockpit sees all switches off. Oil on, fuel on. Controls [deleted] shut [/deleted] set. Air intake shutters fully open. Any cowling gills open. (On aircraft with V.P., prop in fine pitch). Fellow below starts turning starter. When starter going fast enough. Fellow below shouts Contact, chap in cockpit repeats. Fellow below engages dogs. Chap in cockpit puts all switches on & primes then turns hand mag. Check oil pressure, fuel & boost.

Let engine idle until correct oil pressure [inserted] & temp [/inserted] etc. Then check mags. Throttle forward & mixture to rich for take off position, recheck mags. Throttle back to cruising position.

[underlined] To stop engine [/underlined]:- Pull engine back to slow running pos. Pull slow running cut out & engine stops.

[underlined] Coolant [/underlined]:- DTD 344A 30% (Ethylene Glycol + inhibitor)
Distilled Water 70%
Tested for specific gravity by an hydrometer.
Frothing occurs where dirty, wet tins are used, and glycol is U.S.

[graph] AP1464 Graph showing change of S.G. with temperature.

[page break]

Ethylene glycol has corrosion action, be careful of leads [sic] when filling header tank. Use only clean, dry tins.

Jack. drive must be kept from compass 11”. Small hole in flexible drive must be fitted at engine end, to prevent oil from engine working up to instruments.

Capillary tube of oil temp gauge must be kept 7” away from compass.

[underlined] Inertia (Hand Energised) [/underlined]

[underlined] Actions by [/underlined].


[page break]

[underlined] General Precautions [/underlined]:-

1/ Switches off
2/ Place machine nose to wind, chocks in front of wheels.
3/ Fire extinguisher at hand.
4/ All covers & locking devices to be removed.
5/ Check switches to ‘off’, retractable under-carriage lever in down position.
6/ ‘Petrol On’, throttle closed, mixture control in RICH or IDLE CUT OFF according to type.
7/ Airscrew in fine pitch or maximum RPM.
8/ Cowling gills open, air intake shutters open. (if radial engines)
9/ Airscrew should be turned over a number of times by hand, prior to starting, to check for hydraulicing [sic].

[underlined] Starting Procedure (Hand Swinging) [/underlined].
[underlined] Action by [/underlined]:-


[page break]

[table continued]

[underlined] Picketing [/underlined]:- Securing down. Tricycle undercarriage usually picketed tail to wind.

[underlined] Preparation of A/C [/underlined]
1/ See switches & fuel are off.
2/ Consult airframe volume I if necessary, re. nose or tail to wind picketting [sic], anchorage points on A/C, special precautions etc.
3/ Place chocks in front & behind wheels (if only one pair, place [underlined] behind [/underlined] wheels.)
4/ Fit control locking device – apply parking brake.
5/ Fit all covers – position prop.
6/ Picket down A/C.
7/ Fit tents & heaters as necessary.

[underlined] Anchorage points on A/C. [/underlined]
1/ 3 main points, - both sides of undercarriage & tail. (Tricycle under/c nose wheel).
2/ Secondary points, - mainplanes, (with tri un/c-at the tail), & very often if a/c exceeds 36 ft. long, midway under fuselage.
Anchor point on mainplane 2/3 from root.

[page break]

[underlined] Lashings [/underlined]:- Leave a little slack in rope. Where possible use shock absorber lashings for mainplanes. (1/2 ton size for light a/c, 1 ton size for medium & heavy aircraft). For tying ropes use clove hitch & 2 half hitches.

[underlined] Methods of Picketting [sic] [/underlined]:
[underlined] Temporary methods [/underlined]:- Screw pickets (3 sizes) 2’ 3” – 3’ 6” – 5’)



[underlined] Spike or Carver Pickets [/underlined]:-
Single & double types, are used where ground is too hard & stony for screw pickets. Single type, two 3’ spikes, double type 4, 3’ spikes.

[underlined] Loose concrete blocks, sandbags etc. [/underlined]

[underlined] Permanent Picketting Base [/underlined]:-


3 chains are issued to each base, each chain 30ft. long.

Position aircraft on base into wind, in best position for securing down, having prepared a/c, secure down to blocks direct, if possible, if not possible stretch a chain between two convenient blocks and secure.

[page break]

a/c by rope lashing to chain. Should an anchorage point on a/c come well outside the base fasten down to screw or spike pickets.

[underlined] Heaters [/underlined]:- Fitted in cold weather to keep [deleted] eg [/deleted] engines & oil tanks warm, & to keep a/c dry [deleted] it [/deleted] internal.

[underlined] Flameless or Catalytic Heater [/underlined]:- Heat obtained by chemical action only, led [sic] free fuel only, chemical action caused by oxygen, fuel vapour & catalyst.


[underlined] Fireproof Heater [/underlined]:- Fitted with chimney with mica window, and safety covering of gauze for fireproofness. Set wick to burn with a blue flame. Take out of hanger & away from a/c to light.

[underlined] De-Humidifier [/underlined] [deleted] heater – [/deleted] air dryer:- Spring loaded parafin lamp. Burner gallery fits round top of wick. [deleted] Light [/deleted] Keep sloping shoulder of burner gallery in good condition to form a gas-tight joint with chimney, held up against chimney by spring. Gauze covering for safety, lowered before taking near a/c. Baffle box fitted to top of chimney to prevent initial condensation & liquid dropping back down chimney. The dryer is fitted to keep moisture from electrical wiring etc.

[page break]

[underlined] Fuels [/underlined]

[underlined] Types [/underlined]

Non-Leaded 73 Octane Orange NS. [symbol]
[symbol] Leaded 87 Octane Blue (or red) MS. [symbol] Fuels cannot definitely be
[symbol] Leaded 90 Octane Blue-Green S. [symbol] identified by their colours.
[symbol] Leaded 100 Octane Green S. [symbol]

[underlined] Storage [/underlined] :- Main storage tanks, 50 gal. barrels, - 4 gal. tins. (only to be used if marked fuel – aviation)

[underlined] Markings [/underlined] :- A/c marked with Oct No. stencilled near to filler cap of each tank. Containers also marked with oct. no. of fuel they contain.

[underlined] Precautions when refuelling [/underlined] :-

1/ Use correct grade of fuel.
2/ Have fire extinguisher handy.
3/ Earth A/C & tanker, bond nozzle to A/C.
4/ Do not drag hose over A/C.
5/ Do not allow fuel to overflow
6/ Make sure tanks are full.
7/ Replace filler cap correctly & lock.
8/ Fill in F/700

[page break]

[underlined] Methods of refuelling: [/underlined] –

1/ Bulk installation
2/ Tankers & trailers.
3/ 50 gal. barrel & hand pump.
4/ 4 gal. tins, funnel & chamois leather.

Fuel contains octane & heptane. High grade fuels contain most octane. Special engine run on test fuel & then on standard fuel, compared two to find octane of test fuel e.g. Parafin [sic] (low grade fuel, contains a great deal of heptane.)

Idecta & Ducta – trade names for bonded tail-wheel, marked on tyre.

Frictional electricity made when fuel runs through pipe, [symbol] A/C needs earthing.

Leaded petrol contains tetra-ethil [sic] lead to stop detonation.

[underlined] Oils [/underlined]:-

[table of oils]

[underlined] Storage [/underlined] 5 gal. drums, 40 gal. drums. 20 & 40 gal heater & non-heater types of tankers.

[underlined] Markings [/underlined] Containers marked with oil specification
A/C marked, in night colour, with key letter, near to oil tank cap
e.g. T/S X/W Y/Y etc. first in summer, second in winter.

[page break]

[underlined] Precautions when re-filling. [/underlined]

1/ Use correct type.
2/ Bonding & earthing.
3/ Don’t drag pipe over A/C.
4/ [deleted] Fill up [/deleted] Don’t fill right up.

[underlined] HANDLING [/underlined] :- of aircraft.

1/ See that the switches are OFF.
2/ See that the brakes are OFF.
3/ See that the u/c is locked down.
4/ Remove loose tools, cowlings etc.
5/ Inspect tail steering gear & fit.
6/ Ensure clear path for A/C.
7/ Position Propeller.
8/ One man on each wing tip.
9/ One man on tail steering gear.
10/ Men on [underlined] suitable [/underlined] handling points, e.g. leading edges, strut bases, U/C etc.
11/ Man i/c to use foll [sic] :- orders only:- (loud clear voice)

“FORWARD” [2 symbols]
“ASTERN” [2 symbols]
“TAIL TO PORT” [2 symbols]
“TAIL TO STARBOARD” [2 symbols]

[page break]

[underlined] Instructions when plane is ready for take off (Pilots signals) [/underlined] for positioning ready for take off

1/ Chocks away [symbol]
2/ I want to go straight [symbol]
3/ I want to go to starboard [symbol]
4/ I want to go port [symbol]
5/ If ground crew want to stop pilot [symbol] + point to obstacle with other hand.

When pilot is positioned & ready to take off he signals ‘stand clear’ with hand only [symbol]

Signal back ‘All clear’ with a salute.

[underlined] Marshalling when machine returns. [/underlined] (daytime) [symbol]
[underlined] Straight forward [/underlined] – beckon with both hands.
[underlined] Stop [/underlined] – both hands stretched above head.
[underlined] To turn [/underlined] – one hand held above head, other hand beckoning so that machine will turn to stationary hand.
[underlined] Switches off [/underlined] – crossing & uncrossing arms above head.

([underlined] Nightime [/underlined]) Blue torches.

1/ [underlined] Straight forward [/underlined] – point torches at pilot with circling motion.
2/ [underlined] To Turn [/underlined] – hold one torch still & circle with other. Machine will turn to stationary torch.
3/ [underlined] Stop [/underlined] – point torches down at feet.
4/ [underlined] Switches off [/underlined] – point torches down & cross & uncross them.

Torch swung side to side waist high = your chocks have been removed.

[page break]

DI on parachutes

1/ See that scarlet safety thread is unbroken.
2/ See that withdrawal pins are not bent.
3/ See that static cords are serviceable.
4/ Inspect pack cover for damp, dirt, acid & general damage.

[underlined] Maintenance [/underlined] :-

[underlined] 3 [/underlined] Reasons for technical maintenance

1/ To ensure the requisite standard of air-worthiness.
[inserted] 2/ (as many planes serviceable as possible.). [/inserted]
2/ To ensure the degree of serviceability demanded by training and operational requirements.
3/ To ensure the economical use of equipment.

Technical maintenance comprises these seven points

1/ Inspections.
2/ Cleaning & anti-corrosive treatment.
3/ Lubrication of working parts.
4/ Repair under approved schemes.
5/ Replacement of worn or damaged parts.
6/ Embodiment of modifications.
7/ Testing.

[page break]

[table of station organisation]

[underlined] Flights [/underlined]

Minor inspections in accordance with Unit Maintenance Orders part II, this includes inspection, cleaning, simpler processes of anti-corrosive treatments and simple adjustments.

[underlined] Squadron Servicing Parties [/underlined] :- under control of S.E.O. or W/O Engineer, major inspections, repairs & replacements, modifications, and test after repair.

[underlined] Work of allied tradesmen [/underlined] :- (carpenters, electricians, fabric workers etc) employed on general repair work, and items of local manufacture, repairs of M.T. vehicles.

[underlined] Repair Depots [/underlined] :- Major repairs, complete overhauls & renovations of airframes & engines, their components, accessories & other technical equipment.

[underlined] Unit Maintenance Orders [/underlined] :-

Maintenance orders are issued to lay down the responsibilities & duty of all ranks concerning technical examination.

Part I is devoted to the above & is termed U.M.O part I
Part II is termed the maintenance schedule.

[page break]

U.M.O’s part II are issued by the [deleted] station C.O. [/deleted] [inserted] command [/inserted] to describe unit maintenance organisation to co-ordinate the technical work on the station. To define individual responsibility for maintenance,

[tables of AEROPLANE & engine A.P.s]

[underlined] Aeroplane Maintenance Schedule [/underlined] :-

Sect I Between flights & daily inspection.
Sect II Minor & major inspections

[underlined] Sections divided into sub-sections [/underlined]

‘A’ airframe ‘D’ Electrical
‘B’ engine ‘E’ Wireless
‘C’ instruments ‘F’ Armament

Sub-sections divided into assembly groups.

“As” Airscrew “PP” Power Plant “Fu” Fuselage “PI” Mainplane.

[page break]

[underlined] Flight Order Book [/underlined] :- alterations in schedule, notices to FME’s etc, in charge of N.C.O i/c flight. Kept where everyone can read it.

Unstarred items inspected every inspection
* items inspected every second inspection
** items inspected every third inspection
*** items inspected every fourth inspection

[diagram of starred items]

Items which are left to a major inspection are printed in capital letters in Maintenance Schedule.

[underlined] Travelling Form 700:- [/underlined] Next periodical inspection, aero. no. fuel & oil capacity & type. Fuel consumption, total hrs. run & flown, fuel state.

Volume I {symbol]
Volume II Part III [symbol]
U.M.O’s Part II [symbol] these are carried by plane on cross-country flights, but not on operations.
Form 700T. [symbol]
Form 171 [symbol]

[page break]

Four types of modifications.

Class I (N.S.) Mod. Essential to safety, embodiment compulsory.
Class II (N.S.) Mod. Essential to operational efficiency, embodiment compulsory
Class III (N.S.) Simple modifications, embodiment at discretion of command.
Class IV (NS) Modifications which will be embodied, only by makers or when specially instructed by maintenance units, service repair depots or the civilian repair organisation.

Anticipation & delay of a minor inspection does not alter the time of future minors.

Flight & Section Order Book
Unit Aeroplane Maintenance Orders Part I
Unit Aeroplane Maintenance Orders Part II
Unit MT Maintenance Orders PART I (Extracts appropriate to technical vehicles
Part II For technical vehicles on charge.

Technical Training Command Technical Instructions
AP 1095 Electrical equipment manual volumes I & II
AP 1107 Manual of rigging for air-craft
AP 1181 Start assistance for aero engines volumes I & II
AP1182 Parachute manual volumes I & II
AP1266 Notes on use of electrical soldering irons
AP1275 Instrument equipment manual volumes I & II
AP1374 Aero engine magnetos volumes I & II
AP 1477 Notes on metal rigging

[page break]

AP 1464 Engineering manual volume I parts A & B
AP 1464 Engineering manual volume II less sections E, F & J
AP 1519 Air compressor units volumes I & II
AP 1538 Adjustable & V.P. airscrews volumes I & II

AP 113 list of A.P.’s.

[underlined] Log Book [/underlined] :- (1464 volume IIA section 24)

Section I Installation (airframe form 1319 engine 1320)
Section II Certificate of Transfer Log (form 1321)
Section III Flying or running times (form 1322)
Section IV Repair or replacement (form 1323)
Section V Modification log (form 1324)

When the airframe or engine is re-conditioned or completely overhauled, converted to instruction category or written off, log books are closed by completing entries on page 1 of the installation log book the sections are then removed placed in transit envelope (form 1325) & forwarded to A.M. Archives

[underlined] Transfer of log-books [/underlined] – When an A/C is transferred the log-book goes with it or goes by transit envelope (1325)

[underlined] Oil Dilution [/underlined] :-

Oil is diluted with fuel to thin out thick oil in cold weather. Set engine cool down to 15° at night, then run up & press solenoid for about 3 mins while engine is running. Stop engine before you let go solenoid switch.

[page break]

[table of documentation organisation]

Fitting:- of C.S.U.
Check D of R of engine & plug up correct holes
Cockpit lever forward C.S.U. lever to increase RPM position, couple up

Tell coolant tanks by shapes & large bore inlets & outlets.
Saddle tank [symbol] Kidney bean tank [symbol]
3 types of coolants Water, 70° & 30° mixture, 100° glycol.


[page break]

[blank page]


H E Wakefield, “Harold Wakefield engine course notes,” IBCC Digital Archive, accessed September 22, 2023, https://ibccdigitalarchive.lincoln.ac.uk/omeka/collections/document/33728.

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