Aircraft maintenance
Discussion
Lost ranger said:
We hear a lot about how many hours maintenance modern military aircraft need for every hour in the air. But does anyone know the figures for WW2 aircraft? Probably not quite comparable of course due to them not normally lasting long enough for major maintenance.
Refuel, rearm, bosh, off you go...!Most of the maintenance time was probably damage repair.
Lost ranger said:
We hear a lot about how many hours maintenance modern military aircraft need for every hour in the air. But does anyone know
the figures for WW2 aircraft? Probably not quite comparable of course due to them not normally lasting long enough for major maintenance.
I don't know the figures but the aircraft certainly required a lot of looking after aside from patching up – I'm just reading Roland Beamont's book 'My Part of the Sky' and he goes out of his way to praise the ground crews who worked outside in all conditions and all hours to keep the aircraft flight-ready. Merlins, Sabres etc need a lot of looking after, they are after all basically racing engines, being mercilessly thrashed about the sky.the figures for WW2 aircraft? Probably not quite comparable of course due to them not normally lasting long enough for major maintenance.
Yertis said:
Merlins, Sabres etc need a lot of looking after, they are after all basically racing engines, being mercilessly thrashed about the sky.
Well kinda, but a real racing engine, the c.1930 Rolls Royce 'R', was over twice as powerful as a 1940 Merlin and lasted about two hours...!Merlins (and the other 1,000 hp class piston engines - Hercules, Pratt & Whitney 2800 etc) were not too heavilly stressed and were therefore pretty reliable.
The 2,000 hp plus piston engines that were being introduced as the war progressed were more problematic - partly because they were being developed under wartime conditions and also because they were approaching the limits of what piston engined aircraft engines were capable of. Post war, we saw large radial air cooled engines of over 3,000 hp fitted to aircraft like the Boeing Stratocruiser and Lockheed Starliner and these were the most powerful production piston aero engines to go into regular use.
However, they were always less than reliable. It was not unusual to see Stratocruisers arrive at Heathrow with one engine shut down.
The 2,000 hp plus piston engines that were being introduced as the war progressed were more problematic - partly because they were being developed under wartime conditions and also because they were approaching the limits of what piston engined aircraft engines were capable of. Post war, we saw large radial air cooled engines of over 3,000 hp fitted to aircraft like the Boeing Stratocruiser and Lockheed Starliner and these were the most powerful production piston aero engines to go into regular use.
However, they were always less than reliable. It was not unusual to see Stratocruisers arrive at Heathrow with one engine shut down.
Here's the inspection/maintenance/service schedule for a Packard V-1650:
DAILY
Inspect spark plugs and harness adaptors for signs of gas and oil leaks
Inspect ignition harness wires for signs of damage from exhaust leaks
Inspect fuel lines for damage and leakage (with system pressurised)
Inspect engine throttle and carburettor control linkages for full, free and correct movement
Inspect engine for signs of oil throwing and leakage, check all connections for leaks, chafing and security
Inspect coolant pump gland for signs of leakage and tighten if necessary
Turn coolant pump grease cup by one-half turn
Inspect coolant pump and drain cock connections for signs of leakage, ensure safety wiring is in place
Inspect cylinder blocks and heads, radiator, header tank, coolant pump, pipe lines and connections for coolant leaks.
Inspect exhaust manifolds for 'blows', defective gaskets and warped or broken flanges
Check engine mount bolt tightness
EVERY 25 FLYING HOURS
Lubricate all engine and accessory control systems, check all relevant ball/clevis joints etc.
Fill control shaft oiler with Spec.2-27E machine gun oil
Inspect spark plugs, check and adjust gap.
Check operation and integrity of plunger spring in spark plug harness adapters.
Inspect and lubricate magnetos
Check all ignition shielding for security and tightness
Inspect and service carburettor
Inspect all fuel lines and connections (with system pressurised)
Inspect propeller governor/control units for security
Check front-mount propeller bolts for tightness
Check rear-mount propeller bolts for tightness
Inspect induction manifolds for blown gaskets and cracks
Inspect supercharger casings and elbows for cracks or damage.
Clean oil scavenge filter screens and Cuno filter cartridge.
Inspect all oil lines for wear due to chafing or vibration.
Ensure coolant leak drain holes are clear.
Carry out cylinder compression test (turning).
EVERY 50 FLYING HOURS
Inspect magneto
Inspect insulators on magneto end of HT leads and integrity of plunger springs
Check backlash in hand-starting mechanism.
Inspect electric starter unit
Inspect switches and solenoids for security of mountings and all electric connections
Inspect booster coil
Remove and clean carburetor fuel strainer, air impact tubes and boost venturi for cleaning.
Clean air intake screen
Lubricate manifold pressure regulator regulator piston
Remove, clean and lubricate aneroid fuel mixture control unit.
Check coolant specific gravity.
Carry out cylinder compression test (static).
EVERY 100 HOURS
Check resistance of wiring harness cables with HT tester
Replace cam felt oiling pad in magneto
EVERY 200 HOURS
Replace aneroid fuel mixture control unit
Remove, clean and replace priming fuel atomisers.
Remove, clean and replace induction-side flame traps
Drain, flush and refill cooling system.
DAILY
Inspect spark plugs and harness adaptors for signs of gas and oil leaks
Inspect ignition harness wires for signs of damage from exhaust leaks
Inspect fuel lines for damage and leakage (with system pressurised)
Inspect engine throttle and carburettor control linkages for full, free and correct movement
Inspect engine for signs of oil throwing and leakage, check all connections for leaks, chafing and security
Inspect coolant pump gland for signs of leakage and tighten if necessary
Turn coolant pump grease cup by one-half turn
Inspect coolant pump and drain cock connections for signs of leakage, ensure safety wiring is in place
Inspect cylinder blocks and heads, radiator, header tank, coolant pump, pipe lines and connections for coolant leaks.
Inspect exhaust manifolds for 'blows', defective gaskets and warped or broken flanges
Check engine mount bolt tightness
EVERY 25 FLYING HOURS
Lubricate all engine and accessory control systems, check all relevant ball/clevis joints etc.
Fill control shaft oiler with Spec.2-27E machine gun oil
Inspect spark plugs, check and adjust gap.
Check operation and integrity of plunger spring in spark plug harness adapters.
Inspect and lubricate magnetos
Check all ignition shielding for security and tightness
Inspect and service carburettor
Inspect all fuel lines and connections (with system pressurised)
Inspect propeller governor/control units for security
Check front-mount propeller bolts for tightness
Check rear-mount propeller bolts for tightness
Inspect induction manifolds for blown gaskets and cracks
Inspect supercharger casings and elbows for cracks or damage.
Clean oil scavenge filter screens and Cuno filter cartridge.
Inspect all oil lines for wear due to chafing or vibration.
Ensure coolant leak drain holes are clear.
Carry out cylinder compression test (turning).
EVERY 50 FLYING HOURS
Inspect magneto
Inspect insulators on magneto end of HT leads and integrity of plunger springs
Check backlash in hand-starting mechanism.
Inspect electric starter unit
Inspect switches and solenoids for security of mountings and all electric connections
Inspect booster coil
Remove and clean carburetor fuel strainer, air impact tubes and boost venturi for cleaning.
Clean air intake screen
Lubricate manifold pressure regulator regulator piston
Remove, clean and lubricate aneroid fuel mixture control unit.
Check coolant specific gravity.
Carry out cylinder compression test (static).
EVERY 100 HOURS
Check resistance of wiring harness cables with HT tester
Replace cam felt oiling pad in magneto
EVERY 200 HOURS
Replace aneroid fuel mixture control unit
Remove, clean and replace priming fuel atomisers.
Remove, clean and replace induction-side flame traps
Drain, flush and refill cooling system.
Yertis said:
I'm pretty sure it would all be done. There might be hacks for getting stuff done more quickly than in the manual, but the 'erks' wouldn't do anything remotely likely to put an aircrew at risk.
Very hard agree. There's no operational purpose in skimping on mechanical maintenance, and as a pilot you don't want to fly into action wondering whether your ground crew have skipped checking the HT leads or whether the propeller bolts are secure.There's a reason why ground crews worked round the clock when the tempo of war picked up.
Even in the accounts of the Flying Tigers, where they didn't have hangars, were perennially short of spares and had to use convenient tree branches as hoists, there's no record of maintenance being skimped.
Battle of Britain had a scene with two Spitfires undergoing hundred-hour checks amidst the desperate need to keep aircraft flying.
https://youtu.be/ysyn5uQM_Ss
https://youtu.be/ysyn5uQM_Ss
2xChevrons said:
Even in the accounts of the Flying Tigers, where they didn't have hangars, were perennially short of spares and had to use convenient tree branches as hoists, there's no record of maintenance being skimped.
I’m not sure that anyone in their right mind would record that they’d skimped on maintenance. You just use common sense and experience to decide which bits of the servicing can be skimmed over and which can’t, and then sign to say everything has been done. It still goes on, especially in times of conflict. Tony1963 said:
I’m not sure that anyone in their right mind would record that they’d skimped on maintenance. You just use common sense and experience to decide which bits of the servicing can be skimmed over and which can’t, and then sign to say everything has been done. It still goes on, especially in times of conflict.
I think what 2CV means is that there's no historical records of systematic skimping, rather than individuals writing down "Plug leads looked OK so Ieft them alone" in whatever service record document they used. Yertis said:
I think what 2CV means is that there's no historical records of systematic skimping, rather than individuals writing down "Plug leads looked OK so Ieft them alone" in whatever service record document they used.
But it would have happened, regardless. “C’mon, we need that aircraft airborne in 15 minutes!”
“You’ll have to wait chief, I’m still checking the tension of the control cables…”
Click click. Bang!
Tony1963 said:
I’m not sure that anyone in their right mind would record that they’d skimped on maintenance. You just use common sense and experience to decide which bits of the servicing can be skimmed over and which can’t, and then sign to say everything has been done. It still goes on, especially in times of conflict.
I didn't mean official records. Of course no-one's going to jot down in the aircraft's maintenance log " [ ] 100 Hour Inspection - Not Done. Too Busy". I meant in the memoirs and interviews done with the pilots, the crew chiefs and the mechanics in the years since. They talked freely about how difficult it was keeping their aircraft flying at a high operational tempo with rough facilities and very limited parts supplies (mostly solved by pulling parts from damaged/written off aircraft) but no one (that I have read, at least) ever mentioned neglecting inspections/maintenance. Just that the ground crews worked like Trojans to keep the aircraft serviceable, with work usually going on right through the night in shifts while the pilots slept.
My grandfather was ground crew in Bomber Command; he told a story of how one layabout type fudged a job on a Stirling, packing an oil leak with rags and then bragging about it. The aircraft got back ok, but in the meantime the culprit had received a colossal beating behind a crew hut before being reported and packed off.
2xChevrons said:
I didn't mean official records. Of course no-one's going to jot down in the aircraft's maintenance log " [ ] 100 Hour Inspection - Not Done. Too Busy".
I meant in the memoirs and interviews done with the pilots, the crew chiefs and the mechanics in the years since. They talked freely about how difficult it was keeping their aircraft flying at a high operational tempo with rough facilities and very limited parts supplies (mostly solved by pulling parts from damaged/written off aircraft) but no one (that I have read, at least) ever mentioned neglecting inspections/maintenance. Just that the ground crews worked like Trojans to keep the aircraft serviceable, with work usually going on right through the night in shifts while the pilots slept.
I really wouldn’t expect anyone to publicly declare that shortcuts were taken and that they took them, just as I wouldn’t expect a rifleman to write in his memoirs that he shot an unarmed civilian in the back for a laugh. I meant in the memoirs and interviews done with the pilots, the crew chiefs and the mechanics in the years since. They talked freely about how difficult it was keeping their aircraft flying at a high operational tempo with rough facilities and very limited parts supplies (mostly solved by pulling parts from damaged/written off aircraft) but no one (that I have read, at least) ever mentioned neglecting inspections/maintenance. Just that the ground crews worked like Trojans to keep the aircraft serviceable, with work usually going on right through the night in shifts while the pilots slept.
We were the victors, we write the history, we make ourselves look like glorious heroes.
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