Living with the DA3.

 

The following account of living with the Wright Turbo Compound engine comes from an anonymous contributor who was obviously intimately involved with this cantankerous engine. (Although often referred to by its military designation R-3350, the ultimate version of the engine which powered the Qantas Super Constellations was more correctly known by its civil designation of 972TC18-DA3 or just DA3 for short).


Reminiscences of a
Connie Line Engineer.


  • Of standing in the dusk at the end of the Darwin runway and hearing the first 1049 with tip tanks and radome coming over the "hump" at full power - all four engines firing well, PRTs glowing softly in the failing light, gear up - a really magnificent flight memory. I suspect it was EAC bound for Singapore.

  • Flying in the aircraft - the progressive quietness as each engine was moved into high blower and the props coarsened out for high altitude cruise. When limitations were subsequently imposed on high blower (to save impeller bearings) the aircraft seemed noisier all round.

  • The never ending engine changes - on and on, culminating with the disastrous Queen Mother's flight, (VH-EAA March 1958) where at least three of the four engines were changed. Tales of changing engines to the extent that they even refitted a u/s one by mistake, because there were so many on the tarmac that day in engine stands.

  • Engines starting up after inhibiting - flames and smoke everywhere, even flame extending to singe the horizontal stabiliser de-icer boots. The never ending use of vanadium pentoxide for inhibiting cylinders.

  • Dismay at seeing a newly overhauled DA3 returned one week later with a broken front master rod - bell mouthed cylinders, disassembly by crow bar and oxy cutting torch - all that effort wasted.

  • Grease and oil everywhere, the stench of cold degreaser still reminds me of those engines. Grease from the propellor hub had to be scooped out by hand. The foreman who drove apprentices to distraction with the endless cleaning of oil trays and buckets. Oil even blowing around when emptying the huge oil trays. Rag, more rag and yet more rag to clean up. Looking for oil leaks - wash down with white spirit and then run the engine - how any oil leaks were ever found was a miracle, let alone a cracked cylinder base.

  • The engine that came in with a PRT wheel in zone 2 - it had cut clean through the chrome moly engine support mount - supposedly at 14,000rpm. Four drilled PRT blades would break out and shear off the remaining PRT blades.

  • Tedious hours spent lining up exhaust ball joints and still they would leak.

  • Synchronising the dual fuel injection pumps, fiddling with the vernier adjustment at night, torch in hand. Admonition never to put your hand in front of the injectors while they were being tested - and gruesome tales by those who did.

  • The repeated timing of the magneto, and that wretched device the "Time Rite" that seemed to have a mind of its own when it came to timing the engine - the simple box and three lights seemed far more effective.

  • Of "Rocket" *, turbanned like a pirate, setting the valve clearances - rocker box caps off - start from the top or start from the bottom, you still got covered in oil.

  • Tall tales and true of Tony and Al who could reputedly change cabin superchargers single handed.

  • Special tools of every shape, size and description to get at cylinder hold down bolts and nuts - especially when PAL nuts replaced lockwiring - and even some form of plate that was punched over the hexagon surface to ensure cylinders were held down tight. Lockwiring of cylinder bolts was enough to send you demented.

  • Of the DC-4 EBK returning from overseas, bumping the nosewheel at each corner by braking hard to get steerage. When we opened the aft cargo door there were two Canberra Avon engines, one u/s R2000 from the DC-4 and yet another dud DA3 to be winched out and sent for overhaul. I sometimes felt the main purpose of the DC-4 was to move DA3s about the world after Constellations.

  • The endless search for cylinder head cracks - God knows how many hours were spent minutely examining cylinder heads for cracks. The limits on fins cracking and missing must have employed Tech Officers for years.

  • Scooping seagull remains from the carburettor intake - all legs and eggs! The stench of cooked birds, feathers and bits and pieces all round the cylinder baffles - what a task to remove them in the cold and damp of a winters morning.

  • Engine runs at full power - the noise and vibration was unspeakable - the engine checks, magnetos, prop synch and that device of the devil, the ignition analyser with the myriad patterns to memorise - HT failure, LT failure, front bank, aft bank - on and on.

  • Of the aircraft that shed a propellor blade in the USA and had to land at an Air Force Base - the investigation and how the miscreant prop did not hit the fuselage or adjacent engine. (VH-EAO August 1959).

  • Feather checks, fine, coarse, reverse - the hum of the Curtiss prop motor and "whack" of the prop brake as it went in and out.

  • Props hung around the hangar wall off large studs like sentinels awaiting duty, one blade vertical.

  • The ceaseless moving of engine rostrums - noise being moved around - how anyone missed getting a hernia is beyond belief, oily, greasy, heaving into place. Few wheels ever went round - just skittered over the concrete tarmac.

  • Of five foot bars to undo the oil filters in zone 2 after the engine run - more dismay when the filter was full of bronze and steel particles - another engine change for sure - run the engine and hope it would come clean, but it never did. The rain would start, the afternoon shift would be sent to the terminal and wearily the engine change would go on.

  • The intricacies of the PR-58E5 carburettor to understand, with fuel injection- coloring in fuel head power enrichment valves, idle circuits, fuel return circuits. George had mastered it and so had every apprentice better master it. Of trying to concentrate on a summers afternoon in the Hangar 20 tech school while some "experts" were running DA3s at full power for a pressurisation check.

  • Trying to understand BMEP, specific fuel consumption, fluid couplings, compound gearing of PRTs back to the crankshaft - a totally black art.

* Rocket was subsequently identified as Peter John Wilson (9 Feb 1934 - 16 Dec 2009)

 

 

Abbreviations

BMEP Brake Mean Effective Pressure
PRT Power Recovery Turbine



Issue Date Remarks
2 10DEC12
Identified the engineer known as "Rocket".
1 07JAN00
Original issue

 



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