Harold Wakefield York flight engineer course notebook



Harold Wakefield York flight engineer course notebook


Text and diagrams covering Avro York 1 C: fuel system, system selectors, hydraulics, Merlin engine data and systems, Graviner system, cabin heating, lubrication system, aircraft construction, aircraft data, carburettor, power plant, engine handling, de-icing system, pneumatic systems. electrical system, DE Havilland hydromatic prop including feathering circuit, instruments (engine and flight).oleo leg, Mk IV auto controls, all flight controls, wheel extension data, ignition system, mag and valve timing, rigging checks, skin repairs, bleeding hydraulic systems, aircraft jacking, inspections, engine control settings,






Multi=page notebook with handwritten entries


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[underlined] AVRO [/underlined] “ [underlined] YORK [/underlined] “ [underlined] 1C. [/underlined]

NAVAL No. S400.
R.A.F. Form 619


[deleted] MAGENETISM & ELECTRICITY [/deleted]

Notebook for use in Schools

91 6425. Wt. 10947. 1,000 M. Books. J.D. & Co. Ltd.

[page break]

[blank page]

[page break]

[underlined] FUEL SYSTEM [/underlined]


Alclad tanks with aluminium welded ends.
Wing Centre Tank [underlined] only [/underlined] self sealing. }
Pipelines flexible & self-sealing.
Dipsticks in A\C. stbd. Side stewards compartment.

15 lbs [symbol] “ to fuel pump.
8 1/2 – 9 1/2 [symbol] “ to amal. valve. } approx
[deleted words]
If fuel pressure drops below 6 lbs [symbol] “ in carb. fuel warning lights come on.

[page break]

[underlined] Check [/underlined] Pulsimeter pumps for 4 – 7 amps. discharge – ammeter steady.
[underlined] Check [/underlined] fuel contents by dipsticks, guages [sic] & F.700.
[underlined] Check [/underlined] All cocks for easy movements.
Pumps 1 & 2 always [underlined] ON [/underlined] { for take-off & landing
{ up to 2000ft. & above 17000ft.
{ when warning light goes on.
{ when running 4 engs. of [sic] 1 tank.

Start on No. 2 tanks then run on No. 1. then back to No. 2 for T.O.


[page break]


[page break]

[underlined] Cut-Out [/underlined]


Regulates the pressure in system & provides an idling circuit for pump.

[underlined] U\C Selector [/underlined]


[underlined] Hot & Cold Air Selector Rotary Control Valve [/underlined]


[page break]

[underlined] Flap - Selector [/underlined]

[four drawings]

[underlined] Hydraulic Reservoir [/underlined]


Spherical Aluminium welded tank holds pressure better. 2 gals. oil 5 gals air. Perspex window for [underlined] tail-down [/underlined] check

[page break]

{underlined] MERLIN ENGINE [/underlined] (General)

Bore 5.4”
Stroke 6”
Swept Volume 1648 cu.”
Comp. Ratio 6:1
Direction of Rotation .[deleted] 42:1 [/deleted]
Crankshaft L.H.
Prop. R.H.
Camshaft R.H.
Reduction gear .42:1
Supercharger 8.15:1 low gear, 9.49:1 high gear
Engine speed indicator drive .25 clockwise from A bank [deleted] cl [/deleted] camshaft.
[underlined] Props [/underlined] fully feathering hydromatic type with constant speed control.
Dowty hydraulic pumps .502 clockwise
R.A.E. compressor B bank .5 clockwise
[deleted] B.T.H. [/deleted] HAYWOOD air compressor B bank .5 clockwise
Vacuum pumps .828 clockwise
Starter motor 101.7:1 clockwise
Constant speed unit .828 clockwise
Elec generators 1.953 anti-clockwise
[underlined] Coolant [/underlined] 70-30 mixture DTD 344A
[underlined] Oil [/underlined] DTD 472B.
[underlined] Weight [/underlined] 1430 lbs. dry [symbol] 2 1/2% tolerance.
[underlined] Rated Altitude [/underlined] M ‘24’ M gear 9250ft. S gear 16000ft.
2850 + 9 ‘22’ M gear 10000ft. S gear 18000ft.
[underlined] Carb [/underlined] S.U. A.V.T. 40/193.
2850 + 9 at 1000ft M gear 1200 H.P. 1100 H.P. S gear.
[underlined] Min. temps for run-up [/underlined] 60°C coolant 15° oil.
Desirable oil temp 60/70°C. Coolant automatic from 99/105°C

[page break]


[underlined] Oil Pressure [/underlined] 45 – 80 lbs [symbol] “ [underlined] Minimum [/underlined] 30lbs [symbol] ”

[underlined] COOLANT SYSTEM [/underlined]
With 344A glycol any water may be used.
With 344 glycol [underlined] only [/underlined] clear distilled water may be used.
70 – 30 mixture used.
70% water – 30% glycol.
1lb. drop in pressure lowers the boiling point 1°C.
1lb. rise in pressure highers [sic] the boiling point by 1°C.
Before topping up system must be cool, & it is impossible to remove cap until system is cool.
Pressurising is done by means of Teddington header tank relief valve.
Boiling point is reached then the vapour of the liquid equals the pressure of the surrounding atmosphere.

[page break]


[underlined] Components of System. [/underlined]

[underlined] Header Tank [/underlined] situated above reduction gear, fastened in two bolts to reduction casing. Swirl plate in header tank gets rid of gas & bubbles.
[underlined] Filler Cap [/underlined] Situated on side of header tank so that system cannot be overfilled.
[underlined] Pockets [/underlined] 2 at bottom of tank for thermometer connection & for thermostatic switch connection.
[underlined] Radiator [/underlined] 2.5ft. frontal area, secondary surface type.
[underlined] Pump [/underlined] on bottom of wheelcase, driven at 1 1/2 times eng. speed. [deleted] dr [/deleted] centrifugal vane type, driven by splined universal

[page break]

coupling at upper end. Capacity at 2650 R.P.M. is 115 gals. per min. pressure approx. 30 lbs. [symbol] “ takes 8 H.P. to drive. Greased by IRTAVA 34A/121 type B. stores reference. 1/2 turn every 5 flying hours. Drain tap on pump used for filling.

[underlined] Header Tank Relief Valve [/underlined] 1) to fulfil the requirements of a sealed system.
1/ To permit pressure to be built up in system to a limit of 30 lbs. [symbol] “.
2/ To admit air to limit the negative pressure in the system when the engine cools.
3/ To provide an escape valve for an uncondensed gas that may exist in the system.

[underlined] Auxiliary Rad [/underlined] . mounted in the leading edge of mainplane between inboard eng. & fuselage either side. Coolant led from B block of both inboard engs. & pipeline returned between rad. & pump.

[underlined] Acid in coolant [/underlined] , causes of 1) Decomposition of glycol.
2) Coolants in use for too long a period.
3) Acid formation speeded by use of too high a temp.
4) Uninhibited glycol.
5) Contamination from external sources.
causes a) Internal corrosion.
b) Tendancy [sic] for radiator blockage.
c) Electrolytic action causing failure of coolant pipes.

Trithanolimine phosphate in glycol reduces acid formation.
Brass or tungsten pipes reduces action of acid.
[underlined] EC 64 Paper Strips [/underlined] stores ref 4K/2365 immersed in coolant for 5 secs. Lay on sheets of white blotting paper, turn from [underlined] pink to green O.K. [/underlined]
Not safe [underlined] from pink through purple to red [/underlined]

[page break

[underlined] Filling the System [/underlined] use 70% - 30% DTD 344A [underlined] through filter [/underlined]
A/c tail down.
Taps 1,2,3 & 4 open, start to fill & wait until a steady stream comes through each tap then close taps.
Fill as far as possible, refit filler cap & start engine run at 2000 R.P.M. to 40°C. Then stop engine remove filler cap & top up again as required. Run engine at 2500 R.P.M. on ground. If venting occurs above 100°C change header tank relief valve & recheck.

If venting occurs below 100°C, drain system fill with fresh clean water, run eng. to normal running temps. Drain water refill with correct mixture & recheck.

Pressure does not start building up until 105°C is reached.

[underlined] Thermostat [/underlined] at 85°C starts to open at 105°C all coolant goes through rad.

[page break]

[underlined] MERLIN 2 SPEED SUPERCHARGER [/underlined]


At 2650 R.P.M.

M = 8.15: 1 21,957.
S = 9.49:1 25,148.


[page break]

Compressed air into pneumatic ram forces ram down, ram operates change over cock & allows scavenge oil to pass into piston. Piston moves down & [deleted] compresses bob weights & springs [/deleted] & turns cam which pushes forward thrust bearing on M gear, thrust bearing depresses bob weights & spring and dis-engages M gear.

Changing to M gear compressed air is released, ram moved up by string, operates change over cock again allows scavenge oil to bottom of piston, piston moves up & turns cams which disengages [deleted] S gear [/deleted] thrust bearing on ‘M’ gear & pushes forward thrust bearing on ‘S’ gear disengaging S gear. Centrifugal force & springs throw out bob weights on on [sic] ‘M’ clutch. Clutch engage & M gear comes into operation.

[page break]


[page break]

[underlined] GRAVINER SYSTEM [/underlined]

Hand operated}
Gravity Switch}
Impact Switch}


[underlined] Impact Switch. [/underlined]


Operates at 6G.

[page break]

[underlined] Gravity Switch [/underlined]


Only operates with u\c down.

[underlined] CABIN HEATING [/underlined]


[symbol] Hot & cold air ducts.
[symbol] Cold air ducts only.

Master control for hot air ducts & louvres along them.
Not control for cold air ducts.

[page break]

[underlined] LUBRICATION SYSTEM [/underlined]

Stores Ref. 34A/32
Oil – DTD 472B. or DTD 109 if other not available

High Pressure } [symbol]
Low Pressure } [symbol]
Scavage Front Sump }
Rear Sump } [underlined] High & Low Pressure [/underlined]


[underlined] Compound Relief Valve. [/underlined]


[page break]

Oil Pump at 2650 rpm. Circulates 5650 pints per hour.
Main bearings 3600 pints per hour.
Big ends get 400 pints per hour.
S\C rear bearing 300 pints per hour.
Camshafts 200 pints per hour.
Reduction gear 300 pints per hour.
800 pints per hour through back to sump.

[underlined] Tank [/underlined] :- Self-sealing, situated behind fire-proof bulkhead in engine sub-frame – capacity 37 1/2 oil + 4 1/2 air space. Filter in each tank on outlet side.

[underlined] Pressure Pump [/underlined] :- spur gear type mounted on the rear of the underside of crankcase sump.

[underlined] 2 Scavenge Pumps [/underlined] :- 25% each larger capacity than pressure pump. Situated on floor of crankcase rear pump above pressure pump.

[underlined] Scavenge System [/underlined]


Oil Consumption 3.20 pints per hour, consumption should be steady.

[page break]

[underlined] AIRCRAFT CONSTRUCTION [/underlined]


[underlined] Transport Formers [/underlined] 1, 9, 14, 30.

[underlined] Semi- Monocoque [/underlined] construction, formers & stringers. No formers on stringers in F1. Alclad skin. F1 supported by longerons across floor & dural. casting.


[underlined] 17 Parts in Mainplane [/underlined]
Thrust ribs fitted to support engines.

[underlined] THRUST RIB [/underlined]


Rear Spar 8 fitted to A\C
2 to each engine.

[page break]

[underlined] INBOARD ENG. [/underlined]


[underlined] OUTBOARD ENG. [/underlined]

[diagram] [underlined] NORMAL RIB. [/underlined]

[page break]

[underlined] AIRCRAFT DATA [/underlined]

High Wing Monoplane.
Transports convertible to passengers, freight, troops & stretchers.
4 in crew.

[underlined] Main Dimensions of Mainplane [/underlined]:- Incidence 4°.
Datum Dihedral 7°
Top surface dihedral rear spar 5° 19’
Area (including ailerons) [inserted] gross [/inserted] 1300 sq.ft.
Area (including ailerons) net 1190 sq.ft.
Aileron total including 85.5 sq ft.
Trimming Tabs 1.4 sq.ft.
Balance Tabs 2.2 sq.ft.
Flaps 132.2 sq.ft.
Tailplane incidence 30 mins
Area including
elevators & tabs 237 sq.ft.
Elevators total & tabs 87.5 sq.ft.
Trimming Tabs 2.9 sq.ft.
Balance Tabs 4.2 sq.ft.
Fin & Rudder
Centre Fin 37.7 sq.ft.
End fins & rudders & tabs 111.4 sq.ft.
Rudders & Tab 41.2 sq.ft.
Trimming Tabs 2.2 sq.ft.

Span 102ft.
Rudder – Rudder 33ft.
Nose to Tail 78ft. 6”.

[page break]

[underlined] Angle of Movement of Controls [/underlined] Linear Movements
{Ailerons 16° up 16° down 6 3/32” + 3/4”
{Trim Tabs 19° up 19° down 7/8” + 1/8”
{Balance Tabs 12° up 12° down 27/32” + 1/4”

{Elevators 28° up 14 3/4° down 12 9/32” + 27/32 up 6 1/2 & 7/8 down
{Trim Tabs 6° up 6° down 3/16” + 3/32” up 19/16 + 3/32 down
{Balance Tabs 11 3/4° up 22 1/4° down 1 1/8” + 3/16 up 2 7/32 + 3/16 down

{Rudders 22 3/4° in 22 1/4° out 8 23/32 + 3/4 Inwards 8 17/32 + 3/4 Out
{Trim Tab 22° in 22° out 1 29/32 + 3/32 Inwards 1 29/32 + 3/32 Out

Flaps down 56 1/2°

Minimum ground clearance 1ft 8” }
Ground angle at full load 6° } Rigging Position.
Top of Rudder – Ground loaded 21ft. 4” }
Prop. Tip to ground 4ft. 6” }
Engine Props. Inboard Boss to Boss 23ft. 9”
Engine props. Outboard Boss to Boss 50ft 3”
Centre section L.E. to T.E. 16ft.
Aileron 17ft. 3 1/2” x 2’6”

York Pass. 24 40383lbs. Tare Wt.
York Freighter 38000lbs. Tare Wt.
York V.I.P. 40200lbs. Tare Wt.
Max A.U.W. 63000lbs. (Trop Temp) Max. Landing Wt. 56,000
65000lbs. (Temperate Climate)

[page break]

[underlined] Speeds [/underlined] min 95. m.p.h. lift off, light.
Min 105 m.p.h. lift off, heavy.
Safety speed 135 m.p.h.
Climbing speeds rec. 160 mph. 175 mph. comfortable.
Stalling Speeds 63000lbs. flap & u/c up 103 mph. F & u/c down 91
45000 lbs. flap & u/c up 88 mph. F & u/c down 78
Approach Speeds 45000 110 mph. Eng. Assisted Glide 120 mph.
55000 120 mph. Eng. Assisted Glide 130 mph.

Over 260 mph. controls become heavy.

[underlined] CARBURETTOR [/underlined]

If altitude aneroid busts at any height above 3000 ft. mixture obtained will be to [sic] rich due to waisted portion of needle going in jet. This gives correct mixture up to 3000 ft. above it is to [sic] rich & black smoke & danger of fire will follow.

Boost enrichment aneroid gives correct mixture up to +4 by means of parallel portion, above +4 mixture is richened [sic] up to +7 above +7 mixture fully rich as jet is widened by tapered portion. If aneroid bursts parallel portion is pushed into jet giving correct mixture up to +4. If boost is above +4 mixture will be to [sic] weak & detonation and overheating will occur.

[page break]

{underlined] POWER PLANT [/underlined]

Consists of everything forward of the bulkhead.

[underlined] Removal of [/underlined] :- Remove prop. & cowlings. (side first)
Drain oil & coolant.
Turn of [sic] fuel cocks.
Disconnect all connections (34 approx).
Disconnect all auxiliaries.
Disconnect all pipelines.
Capilliaries [sic] at tapping ends (not bulkhead)
Disconnect connections at throttle layshaft.
Attach sling to rear bearer feet & eye behind red. gear.
Crane must be able to take 3000 lb. wt. min.
Slaken [sic] bolts at attachment points.
Take weight on sling & remove bolts.
A & D type transit stands.
Lower on engine, [deleted] ligl [/deleted] line up & bolt down.

Inhibit through plug holes & exhausts & inlet port. 60 – 75 lbs. [symbol] “

[underlined] Attachments [/underlined] :- make sure same amount of movement between cockpit controls & engine controls.

[drawing] Hamilton or Haviland
Disconnect on layshaft first

Before starting prime with oil at pressure guage [sic] connections, after removing two scavenger filters, 2 gals. oil used with 10% petrol.

Replace filters & fill up coolant. Run up at 1200 rpm. Not exceeding 40°C coolant

Then inspect filters etc. refill coolant.

[page break]

[underlined] ENGINE HANDLING. [/underlined]

[underlined] Ground Run [/underlined]

1/ Idle at 1200 rpm. Check mag. switches
2/ When oil reaches 15°C & coolant 60°C open to 0 boost (revs. 2350 approx
3/ Check constant speed.
4/ Fully fine, throttles to gate boost 8 1/2 – 9 & 2950 r.p.m.
5/ Throttle back to +7 check mags.
6/ Throttle back to 0 boost check D/C gear, slight drop in revs, rise in boost
7/ Check slow running 400 – 600 r.p.m.

P.O. P.I. S.I. S.O. } Order 3, 4, 21.
1 2 3 4}

At +9 allow boost to drop to +6 } before changing to ‘S’ gear
+7 allow boost to drop to +3 1/2 }
Fly at gate so long as boost does not exceed +7
Revs. at minimum.
[underlined] Fast [/underlined] Climb 160 m.p.h.
[underlined] Slow [/underlined] Climb 175 m.p.h.
Never exceed 2500 r.p.m. in ‘M’ gear for cruising but change to ‘S’ gear.

[underlined] Endurance [/underlined] Low altitude, minimum revs. lowest possible boost to give comfortable I.A.S.
[underlined] Max. Range [/underlined] reduce to +4.

Never throttle back until revs. are at minimum.

[page break]

A.M.P.G. at 10000ft. fully laden at 140 IAS = 1.25
150 IAS = 1.275
160 IAS = 1.3
170 IAS = 1.3
180 IAS = 1.27
190 IAS = 1.24
200 IAS = 1.18
210 IAS = 1.00

Climbing 160 I.A.S. to 12000ft.
155 I.A.S. to 12 – 18000 ft.
150 I.A.S. to 18000ft 22000
145 I.A.S. above 22000

175 I.A.S for constant speed
5 mph reduction for 1000 gals or 7200 lbs reduction in weight.

[underlined] DE-ICING SYSTEM [/underlined]

T.K.S. icing system for airframes, leading edges.

Fluid used H.63A. Tank & pump in rear of fuselage, 10 outlets to leading edges.

[diagram] 1 & 2 leading edge inb. & outb eng.
3 & 4 Wing tips
5 & 6 Outboard of outboard engs.
7 & 8 Tail plane leading edges.
9 & 10 Tail fins
Odd nos. port side
Even nos. stbd side

Switch on stbd. Side of co-pilots panel, 3 pos. Normal, Auto, Emergency.

[page break]

[drawing] } De – icer Dunlop Wick Baro. Sectional View

Outlet per minute in fluid ounces 1 & 2 5.3 ounces
3 & 4 3.1 ounces
5 & 6 4.5 ounces
7 & 8 4.1 ounces
9 & 10 3 ounces

[underlined] On manual [/underlined] :- intermittent feed 15 secs feed, 60 secs. no feed, green light flickering. Only used when expecting icing conditions before long.

[underlined] Automatic [/underlined] :- intermittent feed as manual. Can be switched on but will not work until icing occurs. If [underlined] no [/underlined] detector [underlined] no use [/underlined] . When icing has finished green light goes off after 3 mins.

[underlined] Emergency [/underlined] :- Gives a steady flow, with red light on & green steady on to [sic] . Don’t use if manual or auto will do.

Endurance on Auto or Manual 5 hrs. 55 mins.
Emergency. 1hr. 12 mins.


[underlined] Windscreen Deicing [/underlined]

Fluid DTD 406A stores Ref. 33C/621
Tank fitted behind starboard cockpit bulkhead, containing 2 gals. One pump on floor by second pilot.

2 Pints per hour at 1 pump per minute. 8 hours endurance.
Clean out with methylated spirits regularly.

[page break]

Kilfrost MK. A1 33C/654 [indecipherable word] for props. if no slinger rings.

[underlined] PNEUMATIC SYSTEM [/underlined]


[underlined] Pressure Regulator [/underlined] 300 lbs. or 470 lbs. [symbol] “ Provides a constant pressure & an idling circuit for pump. Situated of [sic] bulkhead S.I.

[underlined] Pressure Maintaining Valve [/underlined] at 150 lbs [symbol] “ for low pressure system, situated rear of hydraulic panel.

[underlined] Pressure Reducing Valve [/underlined] Lowers pressure for Rads. & S\C. to 200 lbs [symbol] “ rear of hydraulic panel.

[underlined] Bottle [/underlined] placed so prevents regulator chatter & stores air for operation of rads. & S\C without compressor. Rear of hydraulic panel.

[underlined] Filter [/underlined] rear of hydraulic panel.

[underlined] Ground Charging panel [/underlined] Stbd. inner nacelle on auxiliary panel.

[underlined] Dual Relay Unit [/underlined] front of co-pilots rudder bar.

[underlined] Heywood Compressor [/underlined] S.I. A Bank 1/2 eng. speed.

[page break]

[underlined] Pressure Maintaining Valve [/underlined]

[diagram] Closes when pressure drops below 150 lbs [symbol] “.

[underlined] Regulator [/underlined]
Safety spring operates at 70 lbs. above normal pressure.


[underlined] Dual Relay Unit [/underlined]


[page break]

[underlined] ELECTRICAL SYSTEM [/underlined]


Voltage depends on speed & field strength V [symbol] Sx [symbol]

Voltage kept constant by voltage regulator irrespective of eng speed change.

[underlined] Generators [/underlined] – 4, 24V, 1500W, 4 pole, shunt type KX.

[underlined] Voltage Regulator [/underlined] Type F – a/ Voltage unit – top
b/ Current unit


[page break]

1/ Speed increases
2/ Voltage tends to increase
3/ Strength of electro magnets increases.
4/ Pile pressure decreases
5/ Pile resistance increases
6/ Field strength decreases.
7/ Voltage is kept constant

[underlined] Current Unit [/underlined] prevents overloading of generator.

Equalising coil brings all generators voltages down to equal automatically.


[underlined] Cut-Out [/underlined]
When generator voltage reaches that above battery (i.e.) 27 volts points are closed

[page break]

[underlined] Warning Light [/underlined]


Check gens regularly by switching off, & checking each in turn. When 1 gen. is switched on [underlined] its [/underlined] light should go out. (for cut-out & fuse check)

If light comes on while flying it can [underlined] only [/underlined] be generator failed, [underlined] not [/underlined] cut-out or fuse.

Lights will not come on for. failure of cut-out or fuse.

[underlined] Main Power Panel. [/underlined] Stbd. side of fuselage, anywhere.
1/ 4 regulators.
2/ 4 cut-outs.
3/ 4 main – fuses.
4/ 4 resist – rectifying units.

[page break]

[underlined] DEHAVILLAND HYDROMATIC PROP. [/underlined]



In the actual prop. the cylinders are called cams, the outer one the fixed cam, the inner one the moveable one.

The angular slots are known as cam slots.

To complete this assembly a drive gear is fitted to the moveable cam & is mesh with the prop. blade gear. The cam assembly is housed in a dome to which is attached a fitted cam.

[underlined] COURSE [sic] POSITION [/underlined]


[page break]

[diagram] [diagram]

[underlined] C.S.U. [/underlined]

Maintains correct L of attack for selected R.P.M.
Only governs oil pressure to rear of piston to coursen [sic] pitch.
C.T.M above fines off blades, with engine oil pressure to give smoother movement.


[page break]

[underlined] FEATHERING CIRCUIT [/underlined]


Inner tube to front of piston (eng. oil)
Between tube to rear of piston (high press. oil)

[underlined] DISTRIBUTOR VALVE. [/underlined]


[page break]

[underlined] Setting & Assembly of Cam Arrangements [/underlined] .

1/ Line up ‘O’ on fixed cam slot with ‘O’ on moveable cam slot.
2/ Assembly piston & roller pins.
3/ Assembly low pitch stop ring with arrow against fine pitch degree on fixed cam flange.
4/ Assembly high pitch stop ring with arrow against feather pitch degree on fixed cam flange.
5/ Feather cam assembly by forcing piston fully forward, enter & secure on dome.
6/ Turn blades manually to feather pitch.
7/ Offer dome assembly to front barrel half ensuring that marked hole on fixed cam passes over marked dowl [sic] on front barrel half.
8/ Check by turning blade to fine & seeing that arrow on blade is opposite corrects fine pitch degree on barrel flange.

[underlined] INSTRUMENTS [/underlined]

[underlined] Oil, Air, & Coolant Temp. Guages [sic] , [/underlined] work on Wheatstone Bridge principle.

[diagram] Three resistances in instrument itself & one in bulb, any change in temp. is felt in resistance in bulb, destroying the balance & giving a reading on the dial.

Resistance in the bulb made of nickel which is sensitive to temp. changes, other three resistances of special material are not.

Coolant 120°C, oil 80°C & air 0°C, null position, when flight/ground on ground.

[page break]

[underlined] Moving Coil instruments [/underlined]. (oil, coolant & air)


Aluminium plate attached to coil being non-magnetic prevents eddy currents.

[underlined] Fuel Contents Guages [sic] (Desynn System) Oil Pressure & Flap Guages [sic] [/underlined] .

Consists of two main parts, tank unit & indicator.
Float arm, train of gears, & small finger which will rotate.


[page break]

Bad electrical connections } Pointer swinging violently.
Brushes making bad contact on resistance }
A reading 120° out, shows stator lead connections are wrong
A reading 180° out, supply lead connections have been reversed + to –

[underlined] Mk. IV Engine Speed Indicator. [/underlined]


[underlined] Mk XIV Altimeter. [/underlined] Case airtight, one connection at back to static vent. Three evacuated capsules & pointer mechanism. Subsidiary scale incorporated in milibars [sic]

[underlined] Airspeed Indicator [/underlined] Airtight case, two connections at the rear, one pressure, one static. Contains a capsule mechanism & pointer mechanism & really measures the difference between still & moving air. Pressure line to pitot head & straight into capsule, whilst static air is allowed into case around capsule. Drain trap fitted in pipelines. 2 near static vents, 2 mid-fuselage, & 3 in nose.

[page break]

[underlined] Rate of Climb & Descent [/underlined]


Air tight case. As a/c climbs or descends capsule expands or contracts giving movement through linkage to pointer.

As a/c levels out the two pressure [sic] are levelled out by bleed holes & pointer returns to level flight mark, by slowly assuming atmospheric pressure in the case.

Extreme dive or climb strains the capsule. A leak or stoppage in static pipelines will give eratic [sic] readings. A leak in case gives same effect.

Free gyroscope with three degrees of spin, pitch & yaw.
Space gyroscope which stays stationary with the earth rotating around it.
Earth gyroscope mostly used, weights attached to make gyro conform to curvature & rotation of earth.

[underlined] Sperry’s Rule of Precession: [/underlined] – Imagine a torque is applied to the rim of the rotor follow through in 90° in direction of rotation a push at this point will indicate direction of precession.

[page break]

[underlined] OLEO LEG [/underlined]

[underlined] Principle of Operation [/underlined]

a) Loads induced when landing & taxying thrust the lower member up into the outer tube compressing shock absorber & causing fluid to open damping valve & passing to air chamber where it further compresses the air. Simultaneously the piston is driven up the air cylinder by the piston rod.

b) When the load is absorbed by the damping action & further compression the damping valve close & the oil expelled by air pressure is confined to passing through two small holes in the valve. Simultaneously the piston is drawn down the air cylinder & the fluid, trapped between it & damping valve assembly can only escape through the small holes in the valve & piston thus retarding the recoil of the strut.


Pressure to be checked with a\c on ground.

1./ Remove inflation valve & attach inflation adaptor
2/ Operate adaptor to read of [sic] air pressure in the struts
3/ The inflation pressure of the strut is to checked against dimension of ’Z’.

[page break]

4/ Any pressure above max. given for the dimension concerned, the strut must be deflated. During re-inflation the dimension of Z should be measured at intervals since if pressure is very low the dimension will increase during inflation.

[underlined] Oil level Check [/underlined] :- This is done with struts supporting weight of A/C.

1/ As above.
2/ [deleted] Check [/deleted] Operate adaptor to allow air to escape slowly until struts are fully compressed.
3/ If at final stage of compression a spray of oil & air is blown off the oil level is correct.
4/ If however it is not correct connect a simple test rig to inflation valve & then pump in oil till pressure rapidly rises. (Not to exceed 2325)
5/ Gradually release pressure until struts fully compressed.
6/ Remove test rig & inflate with air to a pressure between 945-995 lbs [symbol] ”.

Oil used DTD 858 Stores Ref. 34A/159
or DTD 44 Stores Ref. 34A/43}

Z extension 11”. Pressure 1250 Max. 1200 Min with load 72000lbs.
Y or tail wheel 5” Pressure 650 Max. 600 Min with load 6000lbs.

[page break]

[underlined] MK. IV AUTO-CONTROLS [/underlined]

Elevator Valve, if sticking may be freed by oil.
Rudder Valve, any friction eliminated by weight system giving torque in opposite direction.
Main Switch, must be on, may stick, can be checked by removing cover.

(Disturbance) When the A\C changes course the piston [deleted] valve [/deleted] [inserted] core. [/inserted] is moved allowing air pressure to decrease & increase at the sides of the servo piston, the piston moves & by pulleys & rods operates the control surfaces. As the piston moves the valve casing is moved as far as the piston valve, the valve & casing are lined up again when the a\c is back on its normal attitude.


To change attitude of A\C manually in dive or climb the whole plate is rotated disturbing the balance between the valve & balance weights. (Piston moves)

[underlined] MK VIII [/underlined] Only one plate, no rudder control.

[page break]

[underlined] AILERON CONTROLS. [/underlined] Port side fw



Normal droop inbd. 1/2” – 5/8” outbd. 1/4”
If controls are heavy at high speeds decrease droop to 3/8” min.
If controls snatch at high speeds increase droop to 3/4” max.

[underlined] Flap droop [/underlined] Pump down 1”, adjust on port adjustments on jack until port flap nearly touches T.E. of mainplane. Pump up flap & stbd. flap 3/16 & 1/4” gap, port flap should be right up.

[page break]

[underlined] Elevator Controls {/underlined]


Adjustment point between F.22 & 23.

[underlined] Rudder Controls [/underlined]


Adjust at outbd. ends of push pull connections at tailplane.
adjust at eyebolt on connection.

[deleted] [underlined] Trimming tabs [/underlined] cables down port side of fuselage between formers & stressed skin. Adjust aft turnbuckle on Rib 25.

Adjustment turnbuckles [/deleted]

Balance Tabs on Ailerons & Elevators & [deleted] balan [/deleted] static balance.
Rudder from balance

[underlined] Rudder Trim Tabs [/underlined] adjusted port [inserted] side [/inserted] between F18 & 19, F27 & 28
[underlined] Aileron Trim Tabs [/underlined] forward turnbuckle at Rib 29 & aft turnbuckle at Rib 25 (with flaps down)

With controls at neutral & [underlined] tabs at neutral. [/underlined]
Elevators allowed to be 3/16” out of line.

[page break]

[underlined] Main Wheel Extensions. [/underlined] [underlined] Max. [/underlined] [underlined] Min. [/underlined]


[underlined] Tail Wheel [/underlined] [underlined] Max. [/underlined] [underlined] Min. [/underlined]


[page break]

[underlined] IGNITION SYSTEM [/underlined]

2 Mags. Fitted B.T.M. C5 SE12-S } 1.5 Eng. speed from upper wheel case.

Port mag. clockwise } looking on the driving end
Stbd. mag. anti-clockwise}

Contact breaker covers are connected to link-work so that timing is advanced as throttle opens, 3° from fully advanced at full throttle.


Stbd. mag fires inlet plugs
Port mag fires exhaust plugs

When fully advanced A mag. fires 45° before T.D.C.
When fully advanced B mag. fires 50° before T.D.C.
When fully retarded A mag. fires 25° before T.D.C.
When fully retarded B mag. Fires 30° before T.D.C.

Firing order A 1 4 2 6 3 5
B 6 3 5 1 4 2

Contact breaker points fully advanced .012
Plug points .012
To assist in starting a booster coil is fitted to each engine.

[page break]

[underlined] MAG. TIMING [/underlined]

[underlined] B Mag [/underlined] .

1/ A6 on comp. with A6 EMA on crankshaft opposite pointer.
2/ Check contact breaker points just breaking at fully advanced.
3/ Insulate fork when contact cover is off.
4/ Line up appropriate distributor with appropriate segment, (main brush)
5/ Now offer mag. up to the engine.
6/ Turn crankshaft in D. of R. until A6 IMA lines up on timing disc.

Repeat procedure for A. mag. but line up [deleted] of [/deleted] on 1A6 on distributor. (approx .9° for every serration on vernier coupling)

[underlined] VALVE TIMING [/underlined]

1/ Dis-engage camshafts.
2/ Set A6 & B1 inlet tappets to .025
3/ Turn eng. until disc A6 I0 registers with pointer.
4/ Insert .05 feeler in inlet tappets & turn camshaft in opposite to D of R. until feeler is just nipped, engaged Rt. hand serrated drive shaft to nearest setting.
5/ Turn crankshaft in D of R until pointer registers with B1 IC. Insert .05 feeler in inlet tappets of B1 & turn camshaft in opposite D of R. until feeler is just nipped.
6/ Engage left hand drive shaft to nearest setting.
7/ Replace serrated drive bridge plate & inspection plug.
8/ Set exhaust tappets to .020
Inlet tappets to .010

[page break]

Inlet opens 31°B.T.D.C.
exhaust closes 12°A.T.D.C.
Inlet closes 52° A.B.D.C.
exhaust opens 72° B.B.D.C.

[underlined] RIGGING CHECKS [/underlined]

[underlined] Diagonal Checks [/underlined]


[underlined] Diagonal Checks [/underlined]

Rear slinging socket to Rib 11. Both sides
‘A’ to be equal within 1 1/2”.
‘B’ Rear slinging socket to F30, both sides to be equal within an 1”.
‘C’ Tailplane rib ‘11’ to F23. both sides to be equal within 1/2”.
‘D’ Rear slinging socket to dome nut on outboard eng. both sides to be within 1/2”.
‘E’ Dome nut on outer to dome nut on inner, both sides to be within 1/2”.

[page break]

AP. 2484A Vol I York Handbook
AP 2484 A Vol II PT. I General Orders & Mods.
AP 2484A Vol II PT. II Inspection Schedule.
AP 2484A Vol II PT. III Repair Scheme. (Unit)
AP 2484A Vol III Pt I Schedule of Spare Parts
AP 2484 Vol III Pt II Appendix ‘A’
AP 2337 Wheels, Tyres & Brakes.
AP 2140 B, C & D Merlin 22 & 24 Power Plants.
AP 1464 Engineering Manual. (De-icing etc.)

[underlined] SKIN REPAIRS [/underlined]

AP 2484A Vol II Part III

1/ Negligable [sic]
2/ Damage necessitating repair by patching.
3/ Damage necessitating repair by insertion.
4/ Damage necessitating replacement.

(2 kinds of patches used a) Flush patch (on mainframe tailplane & fin)
b) Surface patch (on fuselage permitted)

Most riveting in Yorks are pop or schobert rivets

[page break]

1/ Check for secondary damage
2/ Classify damage (patching)
3/ Clean up damage (radius corners)
4/ Prepare “split” patch. 1/2” overlap each side.
5/ Prepare “flush” patch. (same measurements as cleaned up damage)
6/ Mark out & drill holes in skin.
7/ Place split patch in position, drill & rivet, after applying anti-corrosive treatment.
8/ Mark out, drill & rivet flush in position.

‘A’ ‘B’ ‘C’ ‘D’

[four drawings]

Insertion used to repair struts, tubes or stringers.

Where you prepare flush patch, prepare insertion.
Where you prepare split patch, prepare two sleeves.

Tube [diagram] place rivets 90° to each other
[diagram] Stringer

[page break]

[underlined] Bleeding Hydraulic System [/underlined] after using Emergency Air.

1/ U/C selected “down”.
2/ E.A. off.
3/ Jury strut in.

[underlined] Bleeding [/underlined]:- U/C.

1/ Allow air to escape from reservoir & top up with fluid.
2/ Slacken bleed screw on top of jack & pump until fluid flows free from air bubbles, tighten bleed screw.
3/ Tap E.A. Shuttle & N.R.V.’s to ensure they are seated.
4/ Select U/C up, slacken bleed screw at bottom of jack & pump until fluid flows free from air bubbles.
5/ Tighten bleed screw, & operate U/C 12 times.
N.B. Aircraft [underlined] must [/underlined] be air tested after bleeding, & U/C should be operated 12 times if this has not been done on the ground.

[underlined] Bleeding [/underlined] :- flaps.

1/ Flaps selected down, slacken starboard bleed screw.
2/ Pump until oil flows free from air bubbles, tighten bleed screw.
3/ Select flaps ‘UP’, slacken port [inserted] bleed [/inserted] screw, pump until oil flows free from air bubbles.
4/ Tighten bleed screw, top up reservoir, operate flaps several times.

[page break]

[underlined] A/C JACKING [/underlined]

[underlined] Tail trestle [/underlined] points at F.32 Two points on top of F32 for slinging.
[underlined] Main Jacking [/underlined] Points for 15 ton jack. Two either side between inboard eng. & fuselage.

[underlined] Inboad [sic] pads [/underlined] – One wheel change & retraction test. Chock other wheel [inserted] fore & aft [/inserted] (no brakes) & tail wheel
[underlined] Outboard Pads [/underlined] – Complete jacking, have gantries at RIB 7.
Weights at picketing points F.19. (2-500lb)



The object of progressive servicing is to enable inspections to be carried out without grounding the A/C for long periods at any one time. The servicing of the A/C has been divided into a series of Grade Inspections. Each inspection is allocated a period of [indecipherable word] time in which to be carried out.

Grade I – Grade I inspection is to be carried out at all stopping places, it will also be carried out immediately prior to flights on all A/C that have not been inspected within the previous 24 hrs. This inspection is a visual one [underlined] only [/underlined] & does not require the removal of any cowlings etc. Time allowed 2hrs.

[page break]

Grade II – The grade II inspection is to include the grade I & will be carried out every 15hrs. flying [symbol] 3hrs. Time allowed 6.
Grade III – The grade III inspection will include grade I & II & will be carried out every 30hrs. flying [symbol] 6 hrs. Time allowed 12.

The grade inspections will be signed for in the travelling copy of the F700 which has been suitably amended. Each A/C should carry a copy of the appropriate eng. & airframe publications. & also a copy of the ordinary maintenance schedule as a temp. measure. Special & tech. instructions will be carried out at base only.

[underlined] Base Inspection [/underlined]

This inspection is to be carried out on each return to base irrespective of the no. of hours the A/C has flown. Records of these inspections are kept at base F700 is used to record work done, also in travelling F700. Time allowed 3 days.

Time A}
Time B} Also carried out at base
Time inspections}

[underlined] Time A [/underlined] This is to be carried out at the completion of first 200 hrs [symbol] 30 hrs; & then after 400 hrs [symbol] 50 hrs.

[underlined] Time B [/underlined] This will be carried out on completion 200-400-800 of 400 hrs [symbol] 50 hrs & every 400 hrs after.

[underlined] Time Inspection [/underlined] These items should be inspected at each eng. change. The engs. are to be changed in

[page break]

accordance with the overhaul times laid down in current instructions. Time allowed 16 hrs.

[underlined] ENGINE CONTROL SETTINGS [/underlined]

[underlined Magnetos [/underlined] Adjust the links attached to each mag. so that these links and the longer arms of the cranks are in a straight line when the mag. is on the fully advanced stop then shorten by half a turn & connect up. Adjust the small rod connecting the short arm of the crank with the carburettor cross-shaft to enable the mags. just to touch the fully retard stop.

[underlined] Change-Over Cock [/underlined] With the carb. cross-shaft in the slow running position adjust the small rod connected to the change-over cock lever so that the lever is in a horizontal position. The length of this rod should be approx. 3 1/16”.

[underlined] Servo Piston [/underlined] The small rod connecting the piston with the carb. cross shaft must be set to 2 9/16” between the pin centres.

[underlined] Rated Boost [/underlined] Set carb cross shaft to rated boost position (the etched line against the joint of shaft housing) Line up scribed lines on cam & rocker of boost control (viewed through inspection hole) & adjust cam rod to suit. Open butterflies to fully open stop & adjust curved rod to suit.

[underlined] Slow Running [/underlined] The carb. butterflies must be on slow running stop when this has been set to required R.P.M.

[underlined] Take-Off [/underlined] Take-off boost is adjusted on the X stop on stbd. side of control shaft. To increase – screw out

[page break]

[underlined] Accelerator Pump [/underlined] . With the cross-shaft in the slow running position the long rod on stbd. side of carburettor must be adjusted so that the small crank arm [deleted] is [/deleted] connected to accelerator pump via a fixed intermediate rod is pointing vertically downwards.

[page break]

[blank page]


H E Wakefield, “Harold Wakefield York flight engineer course notebook,” IBCC Digital Archive, accessed September 22, 2023, https://ibccdigitalarchive.lincoln.ac.uk/omeka/collections/document/33711.

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