Was there anything like a sludge trap built in? They have such thigs on pipelines and refineries.
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Was there anything like a sludge trap built in? They have such thigs on pipelines and refineries.Gateway Aviation in Canada in the late 60s and early 70's when I worked for them had a strict policy of doubling oil changes (so every 25 hours instead of 50 on the Pratt's) and part of their oil change procedure was and oil dilution and to fill the oil tank with fuel and leave sit while doing other work (even if that was only cleaning the aircraft). When the tank was drained the first gallon or so was thick sludge. Same with the oil cooler.
We bought a "new" Otter with some 200 hours on its engine and on its post delivery oil change I had to change oil half a dozen times before the oil filter was clean enough for me to consider letting it fly. Most of those oil changes the oil cooler drain ran like tar. After five hours we did another oil change and the filter was loaded with carbon deposits and oil cooler still did not drain as clean as other aircraft in the fleet that were coming close to overhaul.
Just because there is no dust around does not stop the inside of the engines and oil system filling with combustion byproducts, varnish and other undesirable shit.
At the time Gateway were approved to run their 985, 1340 and 1830 radial engines 50% longer between overhauls than other operators and they had a lower overhaul cost than other operators because there was little or no baked on sludge inside the engine.
I thought I covered that in the bit you didnt highlight. From start to finish the Merlin had a lot of fundamental things changed from the ramp head, carburettors, updraft to downdraft, superchargers and all work on ancilliaries.'As did all the other engines. Like the Merlin the Wright R-1820 more than doubled in horsepower during it's life. The oldest I worked on was just under 700 horsepower and un-geared. The latest I worked on was in the Grumman tracker and produced 1500+hp. If my memory is correct there were some less powerful versions as well.
With most/all manufacturers some models produced no more power than their predecessors but had considerably better operating reliability.
No aircraft engine that I have worked on has a sludge trap.Was there anything like a sludge trap built in? They have such thigs on pipelines and refineries.
Surprising to me, you can isolate the trap and drain it every time the plane lands.No aircraft engine that I have worked on has a sludge trap.
Does the operator's handbook indicate the intervals for a "minor inspection"?The Bristol Hercules VI XI XVI XVII XVIII operators handbook (August, 1945) indicates that they are fitted with centrifugers for the engine oil.
I checked to see how often the engine oil is replaced, and surprisingly the routine maintenance section does not specify any engine oil changes between overhauls.
The oil filter is to be cleaned at each minor inspection.
The accessory gearbox requires oil changes at alternate minor inspections, which is also when the centrifugers are required to be removed and cleaned.
I just did a search for it in our technical section and can't find anything, although a few people were looking for Hercules manualsFlyboy - I am fairly sure I scanned and posted the Hercules 630(?) series Engine Maintenance Manual to the forum so have a look for that. If not let me know and I will post it. I cannot remember if it contains maintenance schedules. We worked from the the schedules in the Airframe manual.
You have better eyes than me! LOL!That manual is in here: Bristol Engines.......... used on the Beaufighter
I'll bet "normal maintenance" on a bird so rare and expensive (i.e. cost to recover, restore, and operate Dottie Mae) is very frequent and detailed. IMHO, probably well in excess of the manufacturer's/military regimen.I wonder what he considered "normal maintenance?"
MiTasol makes great points on his post #13)
With that said I would wonder what the manufacturer's original guidelines were for oil changes on a P-47D, I'd guess the traditional 50 hour increment. The reason why I ask is because to gain an airworthiness certificate for that aircraft, the owner/operator would have to present a maintenance program to the FAA and if the owner/ operator wanted to deviate from what the manufacturer specified in the original maintenance manuals, they would have to put up a very rational and convincing argument. I know on many turbine engines running synthetics, there are no oil change intervals, you just add oil as the engine consumes it providing it is not at an excessive level specified in the maintenance manual.
I've helped maintain a few, and usually most owners go beyond what's in the maintenance manuals and writes that into their FAA approved maintenance programI'll bet "normal maintenance" on a bird so rare and expensive (i.e. cost to recover, restore, and operate Dottie Mae) is very frequent and detailed. IMHO, probably well in excess of the manufacturer's/military regimen.
1) I would say there would be too many differences between these engines to give a meaningful answer. You have air cooled radials and liquid cooled in-line engines listed here - wildly different in operation. Suffice to say, each aeroplane fitted with a certain engine would have a fixed schedule of maintenance (if it survived that long - most did not!).If not damaged in combat or other use, what were the typical hours operation of P&W, Bristol, and BMW radial engines, as well as D-B 600 series, Jumo 200 series, Allison, and R-R Merlin engines before certain maintenance was required?
Fuel (presumably), oil, coolant, hydraulic fluids checked and added for each sortie?
How many hours before "tune ups" like carburetor or FI adjustments, timing, ignition, valve adjustments, spark plugs, etc?
And how many hours before major overhauls, like valves, valve seats, rings, pistons, bearings, re-boring, etc.?
At what point was an engine considered worn out and not rebuildable, and therefore scrapped?
Was the "power egg" system used by most air forces?