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Weathering Tips


John1

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From my other post, you'll note that I visited the very awesome Virginia Military Aviation Museum.   So worth a visit folks.   The part that is truly fascinating is that all their exhibits fly.   When I got there, they had just flown the weekend before and hadn't been cleaned up yet.  So unlike immaculately "restored" museum exhibits, I had a chance to see what real WW2 aircraft looked like after a few flights. 

 

First off was their PBY.   I talked to one of the guides at the museum, he swears that this amount of oil leakage is normal, said if the engines ever stopped leaking, it probably means all the oil is gone.

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Next up is their Gustav, one of only a few that are powered by it's original DB engine.   Not nearly as filthy as the PBY but you can still see some grunge built up after only a few flights. 

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Lastly, their PO-2.  Not a lot of soot but like the others, it's got lots of oil splashed around. 

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After the museum, got a chance to visit NAS Oceana on a "behind the scenes/all access" tour.   I thought these two pics might provide some insight on how grubby some Super Hornet bits can get.

 

Pylons:

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Tanks

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My takeaway from this is that aside from replicating soot and exhaust stains, for piston engined subjects, I need to introduce some fresh oil leakage here and there.   Any suggestion on how to do this realistically, please jump in. 

 

Thanks for looking. 

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Seriously?

 

That PBY's oil loss shown is extreme and not, definitely not normal.

 

Rotating and hot cold / cycle oil seal technology really only reached almost perfection in the last 10-15 years, so that screams lack of proper maintenance of seals never touched in years. Rubber / seals have a finite life.

 

Seal failure and oil loss is the most current suspect for that Avenger beach ditched earlier this year,  oil lost and smoke was ignored the whole flight.

 

10 year old hardly used seals are no good,  70 year ones are dust waiting to happen.

 

 

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I dunno, that looks like way more than the usual amount of oil on the PBY.  I’ve never seen that much pumped over the side and there not be a problem somewhere and sure as hell wouldn’t fly it like that.  Also, docents at museums often enjoy an audience more than they do facts and leave a lot to be desired when it comes to operational knowledge.  These are great shots, BTW.

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2 hours ago, John1 said:

 I talked to one of the guides at the museum, he swears that this amount of oil leakage is normal, said if the engines ever stopped leaking, it probably means all the oil is gone.

Apparently the Blackburn Beverly was notorious for oil leakage, although it was also said that there was an advantage for navigators: you navigated out and followed the oil trail back.

 

I have to say that on the few occasions I've seen G-PBYA lately, she did not seem to have that sort of leakage.

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8 hours ago, LSP_Ron said:

 

Seriously?

 

That PBY's oil loss shown is extreme and not, definitely not normal.

 

Rotating and hot cold / cycle oil seal technology really only reached almost perfection in the last 10-15 years, so that screams lack of proper maintenance of seals never touched in years. Rubber / seals have a finite life.

 

Seal failure and oil loss is the most current suspect for that Avenger beach ditched earlier this year,  oil lost and smoke was ignored the whole flight.

 

10 year old hardly used seals are no good,  70 year ones are dust waiting to happen.

 

 

I kinda thought the same but since I’m no expert on WW2 era radial engines, figured I’d keep my thoughts to myself.   FWIW, the port side didn’t have as many oil splatters, but they were still there.   

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1 hour ago, Citadelgrad said:

That is just a ton of oil.  My thoughts are big radials did notoriously leak, but we would see contemporary photos of them dripping with oil if they leaked like that. That seems catastrophic.

 

I used to live in DC and had never heard of that museum.  THanks for sharing. 

I never heard of the place either, my daughter really hooked me up on this one.   Check their website, sounds like they do flying weekends a few times / year.   My other post has a few more pics and details.  

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  • 2 weeks later...

well, hum, I flew the CL215 some years ago, and altough we were always confined to the most remote area of any airfield we landed in, due to the large amount of oil leaking from the two PW R-2800 (plus it was a great idea to do not walk under or downwind the engines, in the light grey overall we wore on duty) all those spots on the PBY fuselage just seem too much.

doing the transition on that plane I was amazed by the really large oil tanks and by the max allowable oil consumption referred as "normal" by the manuals: by heart something like 120 litres and 60 liters/hour per engine!

but, again, the most of the oil was burned by the engines, only few (hundreds) drops reached the tarmac during the night stops.

 

 
Edited by mc65
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Have you viewed period WWII inline birds from below?  Same.   I've been in commercial aviation my entire life and birds get / are mostly grimy and dirty.  A 70 year old bird I can assure you does not have 70 year old oil seals left installed.   A licensed Fitter or A&P licensed mechanic is not going to leave 70 year old oil seal installed on an engine and sign them off as an airworthiness condition, period.  That does not preclude an owner of a war bird with limited funds from making these decisions on his/her own without proper sign offs, however.  Radial engines leak oil, period.   Not a surprise at all.  The pictures provided are the real deal.   Thank you for sharing what is real.   

 

If you're looking for a glossy painted war bird at an airshow with NO oil leaks you're looking at a contestant wanting a golden wrench award.  

I flew AH-1s in the Army Guard and the tail boom was away covered in black engine soot kindly provided by the toilet bowl apparatus.  Case in point.  

 

Great pictures and thanks for sharing.   

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First question to ask about that PBY oil spatter is how many flight hours does it represent?  Basically what that person told him is correct; If the radial engine isn't leaking oil, it's out of oil.  Pretty sure that any preflight on an aircraft with radial engine(s) calls for pulling the props through to clear the bottom cylinders of oil that's drained down while the engines weren't running, the longer the downtime, the more oil accumulates in the lower cylinders.  Why?  Because gravity works and liquid is not compressible. When the piston moves toward top center on the compression stroke and that cylinder has enough oil in it (yes, the oil will bypass the compression rings), the piston hits a brick wall. If the engine continues to turn, what you end up with is a giant boat anchor because the piston rods will be bent to hell and/or pistons broken on any cylinder that was on the compression stroke that contained enough oil to prevent full piston travel.  Pulling the prop through will expel the oil and sometimes can be as much as a few cups and when the engine fires, all that oil goes out through the exhaust and all over anything in its path.  If when pulling a prop through the crew chief/mechanic feels the prop stop, that's his clue to get out the plug wrench and remove spark plugs to prevent damaging the engine by what we call "liquid lock". Each time the engine sits for a few hours, the prop will need to be pulled through to clear the bottom cylinders of oil; it's just the nature of the beast. 

 

Radial engines are why aircraft such as a P-47D had oil tanks that held upwards of 55 gallons of oil. Big, round engines require a lot of oil and blow it all over the place when the engine is started.  There's no way 70 year old oil seals would be in an airworthy, US certificated and maintained engine.  Aircraft engines have Time Between Overhauls (TBO's) and are required to be overhauled by either hours in operation or calendar time past (i.e., 4000 hours or 10 years, whichever comes first). The engine manufacturer dictates when those intervals occur and will list either one or both in their maintenance documentation.  When aircraft engines reach their TBO's they are often removed from the aircraft, sent back to the manufacturer or authorized repair station (US registered aircraft) for overhaul.  Some reciprocating engines allow what's called a "top overhaul" where the cylinders are removed, pistons, rods, knuckle pins, etc. are cleaned, inspected, repaired, and reinstalled.  Oil seals, packings, and O-rings are "one-time-use" items and are replaced each and every time.  As a licensed A&P mechanic with about 30 years experience, some of it on radial engines (teaching in an A&P school with operational radial engines), I'll say from personal experience, when the round engines start, oil goes everywhere.  I have had to trash more sets of coveralls due to being soaked with oil after running round engines than for any other reason.

 

This is an example of excessive oil leakage from a radial engine:

 

aGjJogS.jpg

Edited by Juggernut
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I’d classify that Jug in the “moderate” leakage range.  
 

Feel bad for the poor pilot who undoubtedly had to open the canopy and stick his head out to see where he was flying.  Feel worse for the poor crew chief who then not only had to clean the exterior but then also had to clean a cockpit filled with oil splatters.   

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