DC-3 From The Cockpit

History.

Ah - the DC3. She needs no introduction - we have all seen her and most likely have flown in one. This grand old queen of the skies is still working for a living in Australia in small numbers, on passenger charters, more than 60 years after her maiden flight. The DC3 owed its origins to the state of the airline system in the U.S.A. in the early 1930s. A new type of airliner, using the latest technical advances in methods of construction and larger capacity engines then becoming available, was planned by the Douglas Aircraft Company to meet a requirement issued by the large air carrier T.W.A. The result was the DC1, of which only one model was built, as the improved and slightly larger DC2 was chosen to fill the order. The success of the DC2 is well documented, one example even gaining a place in the famous England to Australia Air Race of 1934. Due to the large distances involved in American air travel, one of the major carriers, American Airlines, planned to have an overnight sleeper plane on its longer routes, the first one being Dallas, Texas to Los Angeles, California. Based on the DC2 and using many of its components, the new larger plane was known as the DST (Douglas Sleeper Transport), but its official type designation was DC3.

On 17th December 1935, precisely 32 years after the Wright Brothers’ first flight, the DC3 took to the air. The world of aviation was changed forever from that time onwards. Due to the quantum leap forward in technology, this remarkable aeroplane was to have a lasting effect on the progress of air travel and more than 800 civil DC3s were in service, before World War Two saw the mass production of the type as the C-47 Dakota. Apart from the more than 10,000 aircraft built in the U.S.A. in California and Oklahoma, another 3,000 examples were made in Russia and Japan. Even in the late nineties, the type continues to serve with some third world air forces and as commercial aircraft in limited numbers around the world.

Prologue.

As a schoolboy in the fifties I made my initial acquaintance with the DC3, witnessing the arrival and departure of Australian National Airways’ VH-INN on a rainy afternoon at Parkes aerodrome. Later in the 1970s, when several were being flown across Bass Strait as night freighters from Essendon, plus one on airline passenger services around Tasmania from Hobart, I had the good fortune to crew up on all of these operations. Some of the attendant details associated with this style of flying seem to come right out of the pages of an Ernest Gann novel:

... "Two Pratt & Whitney twin-row Wasps growling their synchronised rumble ... the glow of St. Elmo's Fire dancing on the windshield ... water dripping into the cockpit from the escape hatch ... misty morning arrivals at Flinders Island ... gusty crosswind landings at King Island ...".

My endorsement on the type was carried out by a former Australian National Airways DC4 captain, Col Shedden at Essendon and Mangalore. Both locations were very busy aerodromes in the days when the propliner was king of the domestic air routes, as Mangalore was the flight training field for the two Essendon-based major domestic airlines.

With the mandatory pass in the DC3 Pilot Engineering examination in hand, credits in both Instrument Flight Rules theory examinations and considerable instrument flight training in a Beech Baron (on which I already had logged several hundred hours VFR), plus time in the “sweat box” - the venerable old wartime LINK trainer, the stage was set. The aim was to concurrently qualify me for the DC3 2nd Class type endorsement and the 2nd Class instrument rating, to legally entitle me to fly as First Officer on type. This included three night circuits at Essendon after the bulk of the training was behind me. Prior to actually commencing the flying phase, an hour or so was spent looking all over, under and inside VH-TAK, recently restored to immaculate condition by the operator, Forrestair Pty. Ltd. in their Essendon workshops. 'TAK had already logged some 47,000 hours aloft, but certainly did not show her age. Her history included wartime service, and then almost three decades with Trans Australia Airlines, both in Australia and Papua New Guinea, where I had first seen the bird at Bulolo whilst I was flying on light aircraft charter operations from Lae.

Technical.

The DC3 is a twin engined all metal low wing monoplane, fitted with a tailwheel undercarriage. The main gear retracts forward almost completely into the nacelles leaving the lower part of the tyres still exposed. The tailwheel is fixed. The “Three” employs a semi-monocoque fuselage with alclad sheeting. The wing is of full-cantilever, multi-cellular construction with three-spars and stressed alclad skinning in three modules - the two outer wings (swept back at 15.5 degrees) are bolted to the constant chord wing centre section using a flange attachment and 328 bolts per side. The original cover strip over these attachment bolts prevented a visual check of the condition of the join without removal, and later it became mandatory to leave these drag-reducing fairings off. This facilitated the visual inspection of the run of bolts during the pre-flight phase and if any were out of line, signifying looseness or were found to be missing altogether, corrective action could be taken.

Many parts of the DC3 are common to its predecessor, the DC2, and indeed I have flown examples which had obvious DC2 components. Fuel is carried in two tanks either side, located in the wing centre section. The forward main tanks are mounted between the front and centre spars and each have a capacity of 168 Imperial gallons. The rear auxiliary tanks are mounted between the centre and rear spars, with a capacity of 167 Imperial gallons. Fuel grade is 100 octane avgas. Each tank is fitted with a ring-latched filler cap and hinged cap cover fastened with a wingnut dzus faster. located on the wing walkway beneath the windows, and also fuel drains at the bottom of the tanks underneath the wing.

Oil quantity is checked on the top righthand side of each nacelle, using a screwdriver to open the hinged door and lifting the ring-latched filler cap.

Dimensions for the DC3 are: span 95 ft., length 64 ft. 5.5 ins. and height 16 ft. 11.5 ins. Maximum gross take-off weight is 26,200 lbs. (11,884 Kg.) and the empty weight is around 18, 900 lbs., dependant on the aircraft. Therefore the payload can be at least 3 tons or up to 7,000 lbs. on shorter stage lengths. Power is provided by two Pratt & Whitney R1830-92 14-cylinder Twin Wasp radial engines with single stage superchargers, driving three-bladed Hamilton Standard feathering propellers, and rated at 1,200 h.p. for take-off at 2,700 r.p.m. As dedicated passenger aircraft in earlier days the DC3 only had a single passenger door. Freighter DC3 have the C-47 Dakota double doors on the lefthand side of the rear fuselage, but these can still serve as passenger doors, by only opening the forward one. A small set of steps is carried and these hook into two slots in the floor to fit snugly against the external fuselage below the forward door.

Cockpit Layout.

On taking the left-hand seat, looking out of the cockpit windows presented good visibility but the ground seemed a long way down.

This impression had to be overcome, otherwise the tendency to hold off too high during the landing would manifest itself. The forward windows are not very deep by today’s standards, but are adequate, and incorporate a square sliding section as a “storm window” for use in limited visibility to obtain direct vision. For a larger aeroplane, DC3 pilots sit in relatively close proximity, and with a little stretching, each pilot can reach all the controls and switches closer to the other man. As with most heavier aircraft of this vintage, 1930s & wartime, the panel is dominated by the standard, semi-circular control wheel and the central engine control pedestal, on which are mounted throttles, pitch levers, mixture controls, tailwheel lock, fuel selectors, carburettor heat knobs, auto-pilot selector and fuel crossfeed selector, parking brake knob, two trim cranks for aileron and rudder plus the elevator trim wheel.

Above our heads on either side were two roof (or "eyebrow") electrical panels, containing many toggle switches for the various services used. Between these two panels, centrally mounted just above the point where the two windshields meet as a "V" is a small circular panel containing the master ignition switch and the two individual engine ignition "wingnut" switches, each with four positions, Off, Left, Right & Both.

The hydraulic panel and various selectors were located behind the right-hand seat, with the electrical junction box in the compartment aft of the cockpit on the left, just rearwards of the small freight door opening out to the port side. Firewall shutoff valves, C02 valves for the fire extinguishers and the associated engine selector were all found under a floor panel between the two seats.

The ancient HF and VHF radios on board were mounted in the racks behind the hydraulic panel, on the starboard side. The space under these radio racks doubled as an unofficial crew rest area (we carried a foam mattress there) and was a good place to have a nap on a long flight. There was even enough vertical space to sit on a small box and have a crew meal, if someone wanted to sit in your seat!

Standard flight and engine instruments were found on the main instrument board, plus the required radio-navigational instruments. Above the co-pilot's knees, on the right side cockpit wall, were the two hydraulic pressure gauges, the forward one showing undercarriage downline pressure and the rear gauge showing system pressure.

Pre-flight and Engine Start.

A normal walkround inspection has already been completed, including checks of fuel and oil quantities, caps and drains, plus control locks, pitot covers, undercarriage safety locks and chocks removed, all hatches and the cargo load are secure and all ship’s documentation (maintenance release and load sheet) checked and signed as correct. Both pilots are strapped in their resepective seats with rudder pedals adjusted to suit and we are ready to start the two Pratt & Whitneys.

After receiving the all clear from an assistant at the lefthand wing tip, and after all the necessary preparations of switches, levers and selectors have been made, the Number 2 (starboard) engine is cycled through nine blades with magneto switches off and mixture in ICOF (idle cut-off) using the starter. After the ninth blade has been completed the starter is released and the boost pump for that engine is placed on, or if not fitted, fuel pressure is brought up using the hand-powered wobble pump.

The master magneto push/pull switch is pushed to the IN position and engine magneto switches selected to both by the actuating pilot, who then operates both the starboard starter toggle switch and the starboard booster coil toggle switch with his right hand (pressing down), and the starboard primer switch with his left hand (pressing up). The rate of turning of the blades is proportional to the strength of the batteries and in short order, the big radial roars to life amid a clatter on conrods, shaking cowls and a puff of blue smoke.

At this point the mixture control is moved up to the Auto Rich position. Engine speed is stabilised at 1,000 rpm, which must not be exceeded until the oil temperature gauge reads at least 40∞ C, and a check is made of fuel pressure, oil pressure, suction and hydraulics. The procedure is repeated for the Number 1 (port) engine save for one difference: the starter and booster coil switches operated by one’s left hand are pressed UP. After start checks for both engines are now done, which include turning the boost pumps off, placing the hydraulic selector to the rear, turning on inverters and radio equipment plus lighting as required.

Handling.

Again using the checklist, pre-take-off checks are carried out, and we are cleared to taxy for runway 17 at Essendon. On departure, we set course for Mangalore for the bulk of the endorsement training flying.

Let's look at a typical circuit. All checks completed, lined up on the runway centreline, tailwheel lock in, smoothly and steadily apply take-off power, 48" MP x 2700 RPM. The pilot not flying keeps his head in the cockpit, monitoring engine instruments and the airspeed. Acceleration is good, and at around 45 KT a gentle push forward on the control wheel brings the tail up.

Direction requires attention, but smart action on the rudder pedals enables the large rudder to keep us on the centreline. At the dial indicated airspeed of 81 KT, the second pilot calls "V2", confirming the call by holding up two fingers horizontally. A gentle backpressure on the column lifts 'TAK off the ground and into a shallow climb. With positive climb established, 'GEAR UP' is called, and first the undercarriage latch is raised, followed immediately by the big gear lever to the left rear of the co-pilot, being raised.

With hydraulic downline pressure back to zero, the gear lever is returned to the neutral position, and the first power reduction is made, to 41" MP x 2550 RPM. At safety height (obstruction clearance) the second power reduction is made to 32.5" MP x 2350 RPM, and this is recommended climb power, at the book speed of 110 KT I.A.S. Dependant on weight and OAT, rate of climb lies between 500 FPM and 1300 FPM. Normal cruise speed for flight planning is 145 KT TAS at a usual power setting of 31_" MP x 2050 RPM, and the fuel flow would be 80 GPH, which with full tanks could give us eight hours endurance but with no commercially viable payload.

For descent, power would be reduced to a few inches MP under the cruise figure, but RPM would be left at 2050 in most cases. However, we are in the circuit at Mangalore, on downwind. Speed limitation for undercarriage and first stage flap extension is similar: 137 KT & 135 KT respectively but in practice a considerable margin below these figures is used. With gear down and locked and a quarter flap out, we are flying at 125 KT using 25" MP x 2050 RPM.

We are on the base turn and these figures are maintained. Once established on finals, crabbed into a wind well below our crosswind limit of 17 KT, we are back to 95 KT, and at the appropriate times, call for the remaining three stages of flap in one-quarter increments, to arrive at the threshold at 80-85 KT.

A normal holdoff is made, and as the wheels make contact with the ground in a slightly tail low attitude, the back pressure is released and the column moved a little forward to pin her on, in a classic "wheeler" landing. Crosswind handling presents no real problem, with the standard crabbed approach, and straighten with wing-down at the flare technique being used, touching down on one wheel. Once again, we may have to "play a tune" on the rudder pedals to keep the "Three" motoring straight down the centreline.

As speed washes off, the tail is lowered gently on to the runway. Once down to a safe taxy speed, and ready to turn off the runway, the tailwheel lock is disengaged before a turn is commenced. Failure to disengage this lock will result in the locking pin shearing off, rendering the aircraft unserviceable. Taxying speed must be kept to a manageable pace, and the best method of judging the correct speed is to look out of the side windows at the ground. Looking straight ahead over the nose, one appears to be travelling slower than is actually the case. When landing a DC3, three-pointers are rarely done, and then only by experienced pilots, should the company operations manual permit it. Wheeler landings are the order of the day and can be accomplished with a minimum of fuss, allowing more precision in the touchdown. VMC (minimum control speed, one engine feathered, take-off power on the live engine) is 73 KT, and asymmetric handling presents few problems, although rudder pressure required to initially hold course after engine failure (simulated or real) is considerable.

Stalling speed at maximum All Up Weight of 26,200 Lbs is 67 KT, clean and 59 KT full flap, in bothcases power off. Asymmetric flight planning shows that a power setting of 35” MP x 2350 RPM gives a fuel flow for the one engine of 90 GPH at a TAS of 112 KT. Landing at the nearest suitable airport would be uppermost in the pilot’s mind.

Epilogue.

The DC3 was a natural introduction to the larger DC4 and DC6/6B series. Overall impressions of the fabled "Dakota" - a very forgiving aeroplane with practically no vices, able to fly well on one engine, and able to be flown quite safely by most pilots. Having at various times earned my living on both types, the old adage "There's only two aircraft you need to have flown - the Tiger Moth & the DC3" -holds true.

Douglas DC-3 Power Table

*Condition*	*MP - "Hg*	*RPM*	*BHP*	*Mixture*	*F/F*	*Limit*	*IAS*
					per engine
Take-off	48	2700	1200	A.R.	-	2 minutes	81 Kt
METO	42	2550	1050	A.R.	102	continuous	110 Kt
CLIMB	32	2350	780	A.R.	61	continuous	110 Kt
CRZ CLIMB	32	2050	700	A.R.	48	continuous	120 Kt
S/E CLIMB	42	2550	1050	A.R.	102	continuous	91 Kt IAS
CRZ 2 eng.	26 - 32	2050	550	A.L.	39	continuous	145 TAS
S/E CRZ	35	2350	800	A.R.	90	continuous	112 TAS

Propeller RPM Limits

Max. overspeed	3060	30 seconds
Prohibited:	1850 - 2050
Prohibited:	2100 - 2300
Prohibited:	below 1700

Handling Speeds (Kts DIAS - Dial Indicated Air Speed)

VNE	178
VNE dive	222
VNO	160
VA	122	turbulence penetration
VMC	73
V TOSS	81
V CL 2 eng	110
V CL 1 eng	91
V LG op.	137
V LG out	130
V FE	133	1/4 flap
V FE	110	1/2 flap
V FE	97	3/4 & full flap
V Stall	68	0 flap
	63	1/4 flap
	61	1/2 flap
	58	3/4 & full flap
V max X/W	17

DC3 PRACTICAL OPERATING NOTES.

A. GENERAL.

1. Elevator bonding wires are mounted on the two hinges of each elevator- LH wires on TOP; RH wires BELOW.

2. Undercarriage strut extension on TAILWHEEL - rough guide - ONE handspan between
fuselage and wheel.

3. Aileron trim tab is mounted on RH aileron only.

4. Wing attachment bolts: total of 328, 132 on TOP, 196 BELOW Look for ODD MAN OUT to ensure none have become loose or dropped out.

5. Undercarriage retract jacks; early model C47 - fitted with bungees; late model C47B - has hydraulic retract jack.

6. Alternate static source is located in LH AUX TANK bay.

B. NORMAL OPERATIONS.

1. Feather Button security: always check that each feather button has not unscrewed itself due vibration. If feather button separates from unit during ground feather check, to stop feather action, momentarily switch OFF Battery Master. Feather circuit is connected direct to battery.

2. Pitot heat check: During pre-takeoff drills, switch each individual pitot heat selector ON, and note the increase in ammeter reading.

3. Magneto checks in flight: Autopilot OFF, Mixture RICH, throttle back to 23-23" Hg, THEN check each mag.

4. Priming for start up: Use boost pumps or wobble pump or crossfeed momentarily.

5. Wheelwell inspection preflight: Oil draincock shut/lockwired, Fuel strainer drains shut (plunger down).

6. Tailwheel lock: When aircraft is parked with tailwheel askew, check that lock is OUT in cockpit and brakes are OFF.... THEN PUSH rear fuselage to align tailwheel; rebrake and relock.

7. Low downline pressure in flight: Select flap up/down momentarily. Pressure drops sufficiently in systems gauge to allow hydraulic accumulator to build up pressure again - allowing U/C downline pressure to raise above the minimum 500 p.s.i. for landing.

8. Use of crossfeed to prime engines during start up is limited to when MAINS are not BRIM FULL. If so, fuel line pressure builds up to the point where fuel overflows out through the fuel tank caps.

9. FIRST 30 minutes flying MUST be on MAINS - otherwise, bleedback at 10 gph occurs into MAINS - and then overflows out of the tank caps.

10. Burning off mags.: If sparkplug fouling due to oil buildup is suspected from rough running
indications, use as follows: - POWER to STATIC BOOST (30in Hg) and MIXTURE to AUTO LEAN for 30 sec.

11. GENERATOR drops out in flight: Switch OPPOSITE GEN OFF to restart failed generator OR KICK junction box (next to Forward cargo door).

12. To realign gyros without dis-engaging autopilot:-Turn RUDDER servo speed valve back to ZERO, SET gyro to compass, reset speed valve to previous setting.

13. Judder in hydraulic system on gear/flap selection: - Pull HYD SELECTOR FORWARD briefly to relieve pressure.

14. If running auxiliary tank dry:- Reduce Power to 22-23" MP as fuel pressure WNG LITE comes on, to prevent surge.

15. To prevent OIL WAXING in prop. dome after standing in low O.A.T. - on runup - PROPS TO FULL DECREASE several times.

16. Shut-down after flight:- one engine at a time to check VACUUUM PUMP operation.

D. EMERGENCIES.

1. Both engines out glide data:- BEST L/D ratio I.A.S. is 98 KT with 18º Flap selected. Height loss is 1000 ft. per 2 NM forward, i.e. at 10,000 ft. max. glide distance with BOTH engines out and propellers FEATHERED is 20 NM, if destination is at sea level. ALLOW FOR terrain elevation!

2. Static selector could inadvertently be reversed during ground maint-enance - IF SO, when NORMAL selected, IAS over-reads by 12 KT, and with ALTERNATE selected IAS
over-reads by 10 KT. If CRZ IAS is 10-12 KT above NORMAL of 135 KT, notify engineers on return to base.

3. Engine failures.

Cylinder separation/cracked cylinder: M.P. drop/backfire/Oil psi drop.

Induction pipe loose: Power loss with all other indications normal.

Supercharger failure: Surge or oscillation in available power.

Main bearing or Master rod failure: Rapid oil pressure drop with marked increase in oil and cylinder head temperatures.

One magneto fails in flight: Partial power loss shown by drop in M.P., select GOOD magneto only and use maximum of 23” M.P.

Inflight hydraulic lock - unable to obtain any services:-
Hydraulic selector FORWARD
FEATHER SBD ENGINE
Dissipate hydraulic psi by exercising flap/brake
AFTER ALL systems psi is gone -
HYD SELECTOR REAR
UNFEATHER SBD ENGINE - watch rpm

PRE-FLIGHT DUTIES - 4 PHASES – INTERNAL, WALKROUND, FUEL & OIL QUANTITIES, DRAINS.

Phase 1.

Standard observation of internal & cockpit checks, battery master and magnetos OFF, Fuels ON (for drains) Downline psi checked - pump by hand if necessary, using emergency pump handle. Brakes ON, Seat/rudder pedals adjusted - own seat only. Personal headphones plugged in / HYD LEVEL OK, appropriate maps/charts stowed near seat.

Phase 2.

Standard walkround Inspection. Remove all gust locks, except rudder if windy - OR - select Autopilot. Commence at LH wing root, check top and underside of wing and flap surfaces, trailing edges. Look along top of wing attach line for protruding/missing bolts. Check aileron for condition and freedom of movement, wingtip and NAV LITE, then leading edge and landing light cover, including safety wire fitment. LH engine nacelle SIDE & BOTTOM cowl fasteners for security, wheel well check - shutoffs/drains secure, inflight braking strap, under-wing attach bolt check - main wheel and tyre Front of engine - crankcase, ignition leads, cables. Remove both pitot covers, check each pitot head for clear dynamic and static ports. Underbelly: Hatches/covers secure - use screwdriver as required. All aerials secure & present. FWD fuselage, under F/O's window - C02 blowout plugs intact (2). REPEAT all preceding steps, in reverse on PORT side of aircraft. TAILPLANE check: - L.E.'s, then RH elevator, tailcone, LH elevator, RUDDER & FIN, Beacon/nav. lite. Check tailwheel strut and wheel/tyre assembly. Check aft cargo hatch secure (if fitted).

Phase 3.

Use stepladder to carry out fuel and oil quantity checks on both sides. Check all covers/panels/caps secure; note quantities obtained on dip. Advise captain of fuel state. If oil low, arrange top-up with refueller.

Phase 4.

Carry out all required fuel drains underneath the FWD centre section, two drains per tank - use milk bottle or similar size clear container.

PREFLIGHT INSPECTION COMPLETE.