Pot metal cause major headaches on C130

[redrider90]

I never have and still do not understand exactly what pot metal is except it is cheap and you cannot weld nor braze it and it rusts.
But this is a fascinating story about how a small pot metal rivet has been causing major health issues for the flight crews of the C130.
And instead of experts it literally took the fly boys themselves to figure it out. The longest running plane in production history and they are just now finding the source of the problem. And why would they use a cheap piece of pot metal on an otherwise fully stainless valve? All to save a buck.
http://www.sunherald.com/2015/04/09/6168089_in-flight-mystery-keesler-airmen.html

"It took 500 man hours and disassembly of about 65 percent of the system before they made the crucial discovery. The metal particles were coming from a corroded rivet, no larger than a pencil point, inside an air valve."The corrosion had remained hidden for years because every other part of that valve is stainless steel. But not the tiny rivet, which is composed of plain pot metal -- an inexpensive, low-quality alloy".

[mgfan]

Yea, but was it Chinese pot metal ?    :BEER:

[Triple Jim]

I never have and still do not understand exactly what pot metal is except it is cheap and you cannot weld nor braze it and it rusts.

It originated as an alloy made by throwing mostly non-ferrous metal scraps into the pot and melting them.  It usually has a lot of zinc in it.  There's a pretty good description here:  http://en.wikipedia.org/wiki/Pot_metal

[guzzitime]

Worst airplane for oil leaks?  You must be young enough not to remember the beloved Radial engines.  P&W 2800, Curtiss Wright 3350,  P&W 4360 and others.

[Penderic]

Pot too small. Use tray.

 ;D

[redrider90]

All this talk of pot , hmm , where are the cheetoes  ???

  Dusty

Just a few more days Dusty and you got the whole campground and then you can start a fire with smoke. I'm not saying anything here about your heritage now. ;D
 I am just talking about pot hum I mean pot metal  8)

[Triple Jim]

Worst airplane for oil leaks?  You must be young enough not to remember the beloved Radial engines.  P&W 2800, Curtiss Wright 3350,  P&W 4360 and others.

I've talked to my father about the R-2800.  When a friend was talking about how much oil they burned in Vietnam helicopters he flew in, I asked Dad if he remembered an oil burning problem when he piloted his C-46 in WWII.  He said that if they had burned any abnormal amount or oil, or leaked any, they would have gone in for service immediately.  It seems that during WWII, the cargo planes were well maintained.

[Lannis]

I've talked to my father about the R-2800.  When a friend was talking about how much oil they burned in Vietnam helicopters he flew in, I asked Dad if he remembered an oil burning problem when he piloted his C-46 in WWII.  He said that if they had burned any abnormal amount or oil, or leaked any, they would have gone in for service immediately.  It seems that during WWII, the cargo planes were well maintained.

I guess today we may have a different idea of what's considered "normal" oil consumption.   One B-17 radial engine (according to the mechanic who was maintaining the last one that showed up here) burns or leaks about 2.5 gallons per hour of flight, so a 2 hour flight would use about 20 gallons of oil.   That's a lot of oil in our minds, maybe not so much to a 1930s radial designed for performance and to haul the bombs there regardless of the EPA ...

Lannis

[Triple Jim]

Those were the kind of consumption numbers I ran past Dad, who said that when he was flying, that would have immediately sent the engine(s) for rebuild.

[Bill N]

Not sure how this thread drifted to the C-130 but hey it's interesting. After reading the article it mentioned the problem began with the newest version, the C-130 J. All the previous models dating back to the 50's as far as I know didn't have the problem. I never had any problems with it in my 28 years being involved with the C-130. Oil leaker? Not so much. The engines have a fuel drip valve that allows small amounts to drip during start and shutdown. If props leak, it's fixed right away. Any engine oil leaks are also fixed right away.  Compared to internal combustion engines these turbines are much cleaner.
Bill

[Murray]

Worst airplane for oil leaks ever.  They mark their territory like an old MG.

The E's and the H's weren't too bad the ones we had, most of the US aircraft that came to visit (mainly marines) always had that flogged put away wet, patched up with what we'd considered get me home repairs as a permanent solution.

Although by far the worst I came across for oil leaks was the F-111 the engines weren't too bad the hydraulic system on the other hand made the DHC4 Caribous with their radials look good. Anecdotally the radials that really ate the oil were the sleeve valves. Although I do remember someone talking about when one of the other squadrons I was in went from Neptunes to Orions they went from taking  200ltrs drum of engine oil on deployment for aircraft with two engines to a couple of gallons for an aircraft with four and not really expect to use it the Wright Cyclone ran a fair bit of boost.

[redrider]

Never added much to the transient 130, 141,C-5 guys. Oddball 106's, 104's and a Canberra now and then were treats.

[mtiberio]

The joke on those old planes, "check the fuel and fill the oil"

[pete mcgee]

Good find by the guys, intermittent problems in a system that complex and large is really hair pulling territory, full marks to whomever had the clout to keep the aircraft on the ground until a problem was found.
I have worked on both F111's and dhc4 Caribous.
Caribous R2000 radials usually used 1 us gal of 60 wt oil per hour straight out of overhaul, at 1.5 gal per hour it was sent for overhaul, wartime flog the bum off it was 2 gal per hour.
Thats just the oil burn, leaks were another issue altogether 14 cylinders each with 7 places to leak and probably another 15 in various other places, after flights were "fun".

Tf 30 jet engine in the F111 generally used bugger all oil as mentioned above the static leak rate of the hydraulics was impressive up to a pint overnight from each of the stabilator rams and smaller amounts of oil from various other drains.

[56Pan]

(snipped)

Caribous R2000 radials usually used 1 us gal of 90 wt oil per hour straight out of overhaul, at 1.5 gal per hour it was sent for overhaul, wartime flog the bum off it was 2 gal per hour.

(snipped)

Little confused here.  The R2000's were P&W's like the R2800's I used to work on.  The 2800's used straight 50 wt. oil.  Yours used 90Wt?

[Murray]

DHC4's would of been running in at least the sub tropics and normally the tropic's/dessert so not too much of a stretch they used a heavier oil in them.

[pete mcgee]

Little confused here.  The R2000's were P&W's like the R2800's I used to work on.  The 2800's used straight 50 wt. oil.  Yours used 90Wt?

It appears not, I put it down to a seniors moment.
The oil was OMD-370 which is 60 wt.