PPG Reports Tank Top Sealant May Dissolve in 100LL

[mattbucy]

I posted this to the MAPA list and am cross posting here because it may turn out to be important.

Long story short, I've been dealing with an engine contamination event after a tank reseal that caused a mid-flight shutdown of a 57-hour old engine and coated the cylinder interiors with a black, gunky substance. I, with my insurance company and mechanics, have explored all kinds of theories as to what happened. We've had lab tests made of the fuel (negative for Jet A) and will soon have results from testing of the black, gunky substance once the engine is opened up. FYI, all fuel filters were 100% clean. The new tank sealant is holding fine. Compressions on all cylinders cold is in the 70s. Engine monitor data suggests fouled plugs caused the shutdown. The shutdown was brief, the engine ran roughly for about three minutes, then cleared itself and ran normally until landing, after which the interior contamination was discovered and the plane grounded.

Two days ago, on a lark, I opened up one of the plane's fuel tanks to check the fuel. It's tanks are full and they have sat undisturbed for two months as we've puzzled. The fuel smelled horrible and looked strange, stringy. This suggested to me something was leaching into the fuel from the tank sealant. What else could it be? My mechanic made a call to PPG, the manufacturer of the sealants used on my reseal. They informed him that while the main sealant used, PR-1422, is insoluble in fuel, they have had reports recently of the recommended protective top coat sealant PR-1005-L dissolving in 100LL. They no longer recommend its use. However, it is specified by Mooney's tank sealing manual, which I expect is the bible for lots of shops. The PPG rep described to a tee what the inside of my engine would look like if PR-1005-L was run through it: a black, tarry gunk throughout. Bingo. Apparently, some 100LL will dissolve it completely such that it flows right into the engine with the fuel and is not caught by fuel filters.

I'm posting this hopefully not to needlessly alarm, but to inform the Mooney community that there seems to a problem with this sealant, according to its manufacturer. I'm not sure why they haven't made a statement to this effect. They did tell us emphatically not to use it and to strip any remnants of it from my tanks before running an engine on the tanks. While I cannot be certain yet that this sealant is the culprit in my engine troubles, it is so far the only candidate that makes sense. In 2009, the NTSB investigated an accident that specifically implicated this sealant. Vans has issued a SB that this kind of sealant is not to be used. PPG says they have advised Mooney but, as far as I know, no SB has been issued. PPG says most of the cases reported to them are Mooneys, probably because Mooneys have more tank work and reseals than other GA planes and the Mooney manual specifies this top coat for reseals and repairs. If I understand the history, PR-1005-L was designed long ago for pre-100LL fuels which were formulated differently. The last application bulletin for it was written in 1972! I advised my tank reseal shop and they're looking into it.

In a nutshell, if your fuel smells and looks fine, I doubt you have a problem. However, if you have had recent tank work in which PR-1005-L was applied, I would keep a close eye on your fuel, especially if your plane sits for longer periods where fuel could work on the sealant. If you ever notice your fuel looks sort of stringy when agitated in your sumping container or smells like rotten rubber, I would not fly. You may also be able to visually determine if you've got this sealant in your tanks. PR-1005-L is clear but red in color and appears as a red tint over the darker main sealant. Other manufacturers may also tint their top coats, but if you know you've got PPG sealants, the red would be PR-1005-L.

Here's a link to video I made of 100LL contaminated with a bit of Jet A. We determined Jet A was probably not implicated in my case, but my contaminated fuel looks a lot like this. 

 

-Matt

[Piloto]

Unlike PR-1422, PR-1005-L is like a lacquer that dissolves easily with MEK. It was never recommended for the Monroy Long Range tanks by recommendation from PRC de Soto. The problem with PR-1005-L is that with time it start peeling off and maybe clogging the drain holes on the ribs and drain valves.

José

[carusoam]

Great that you are bringing this to everyone's attention.

Got any more detail on your engine out experience?

Best regards,

-a-

[nels]

Did you clarify with ppg that this is a NO alcohol fuel? I noticed, while wiping down the tank with alcohol, that the top sealer did soften. I also remember the POM allowing the use of only a certain specicific alcohol for winter use added to the fuel in a limited amount. The softening while wiping, did raise a question in my mind and I figured that was why they allowed a certain alcohol blend only. I'd look it up but im in a camper in the middle of Kansas.

[DVA]

I think we all need to be careful before jumping to conclusions here.

Fuel tanks repairs and reseals have used various manufacturers' Buna-N for decades now under the influence of 100 LL without known issues.

Mooney, still to this day, prescribes the use of Buna sealants in the fuel section of the official maintenance manual.

There are easily a number of potential confounding factors here that could have cause Mattbucy's problem. And thank goodness he was able to land safely to talk about it.

I am making calls today to both PPG and Flamemaster and I'll share any new info I get.

[mattbucy]

Nels,

We described our situation and they said they've recently had roughly a report a month, mostly from Mooney owners, who are seeing problems with this top sealant. Their guess is that the fuel may have had alcohol in it, that distributors have been known to cut 100LL with small amounts of ethanol. They said just a small amount of ethanol will compromise the sealant. But, I think that's just a guess. 

Like I said, in my case we are not certain this sealant is the culprit. But, I relay this information because it came from PPG and seemed important to get out there. In a few weeks, once my engine is torn down, and we can test the contaminant, we ought to have a better idea. PPG gave us specific things to look for in the contaminant that would be signatures of the sealant.

-Matt

[nels]

17 minutes ago, mattbucy said:

Nels,

We described our situation and they said they've recently had roughly a report a month, mostly from Mooney owners, who are seeing problems with this top sealant. Their guess is that the fuel may have had alcohol in it, that distributors have been known to cut 100LL with small amounts of ethanol. They said just a small amount of ethanol will compromise the sealant. But, I think that's just a guess. 

Like I said, in my case we are not certain this sealant is the culprit. But, I relay this information because it came from PPG and seemed important to get out there. In a few weeks, once my engine is torn down, and we can test the contaminant, we ought to have a better idea. PPG gave us specific things to look for in the contaminant that would be signatures of the sealant.

-Matt

 

17 minutes ago, mattbucy said:

Nels,

We described our situation and they said they've recently had roughly a report a month, mostly from Mooney owners, who are seeing problems with this top sealant. Their guess is that the fuel may have had alcohol in it, that distributors have been known to cut 100LL with small amounts of ethanol. They said just a small amount of ethanol will compromise the sealant. But, I think that's just a guess. 

Like I said, in my case we are not certain this sealant is the culprit. But, I relay this information because it came from PPG and seemed important to get out there. In a few weeks, once my engine is torn down, and we can test the contaminant, we ought to have a better idea. PPG gave us specific things to look for in the contaminant that would be signatures of the sealant.

-Matt

Matt, could you check your fuel to see if it might be laced with alcohol?

[markejackson02]

That sounds really weird that they would cut an aviation fuel with a non-approved substance.  Huge liability.

Van's strongly discourages the use of slosh sealants/top coats.  If used properly they are okay but they require meticulous surface preparation and you have to use the right one with the right sealant or they will behave as you describe.  I'm surprised that anyone would use anything other than proseal or the equivalent inside a fuel tank.

 

[mattbucy]

Nels, we may. Good idea. But, we're looking to the contaminant itself first since we want to know where this stuff came from.

[N201MKTurbo]

I have a pint of that stuff in my hangar that is about to expire. Expensive stuff. I have it in my tanks right now. Most of us do. All of us should.

I doubt that they add Alcohol to the fuel on purpose or even on accident. I know that sometimes accidents occur where mogas is put into the delivery truck instead of avgas and they get mixed. Almost all mogas now has ethanol added. I know ethanol will not only dissolve the top coat, it will soften the sealant almost as good as MEK.

I found this out a while back when a friend was helping with some tank work. I sent him home with the cover plates and some MEK and he was going to clean them up and bring them back. When he came back he said "Screw that MEK, it's nasty. I used Denatured Alcohol and it worked better". So I tried it and he was right, it worked pretty good for cleaning off the sealant and doesn't have near as much of that evil chemical smell.

[neilpilot]

1 hour ago, N201MKTurbo said:

 I know that sometimes accidents occur where mogas is put into the delivery truck instead of avgas and they get mixed.

I assume that, as you say, you "know" that this sometimes occurs.  I'm surprised by this.

I had thought that in North America 100LL has to have it's own dedicated equipment, which is one of the factors in it's high cost. The tetraethyl lead is quite persistent in pipelines, tanks, and hoses/lines, which will cause contamination of other fuels. 

[takair]

Didn't we have a thread recently where someone showed a cylinder wall with mysterious dark "stains"?  Can't recall the outcome.  I wonder what the combustion looks like with this contamination?  Wonder if one of the oil analysis labs would take on a sample of fuel to test?

[N201MKTurbo]

1 hour ago, neilpilot said:

I assume that, as you say, you "know" that this sometimes occurs.  I'm surprised by this.

I had thought that in North America 100LL has to have it's own dedicated equipment, which is one of the factors in it's high cost. The tetraethyl lead is quite persistent in pipelines, tanks, and hoses/lines, which will cause contamination of other fuels. 

In 1986 at the Aurora Airport in CO. the gas company filled our 100LL tank with premium unleaded.

[N201MKTurbo]

1 hour ago, neilpilot said:

I assume that, as you say, you "know" that this sometimes occurs.  I'm surprised by this.

I had thought that in North America 100LL has to have it's own dedicated equipment, which is one of the factors in it's high cost. The tetraethyl lead is quite persistent in pipelines, tanks, and hoses/lines, which will cause contamination of other fuels. 

In 1986 at the Aurora Airport in CO. the gas company filled our 100LL tank with premium unleaded.

[N201MKTurbo]

Wow, that's weird

[neilpilot]

Just now, N201MKTurbo said:

In 1986 at the Aurora Airport in CO. the gas company filled our 100LL tank with premium unleaded.

Did they receive and off load an entire auto gasoline tanker?  I ask because that's possible, and is quite different from mixing the two fuels. That can result if a driver hooks to the wrong tanker, and disregards the tank # on his bill of lading.

I worked in the petrochemical industry for decades and have seen this happen a few times with other commodities. Quite different from contamination due to mixing. That can happen even with a dedicated 100LL fleet.

[neilpilot]

Do I need to repeat my last post 

[N201MKTurbo]

28 minutes ago, neilpilot said:

Did they receive and off load an entire auto gasoline tanker?  I ask because that's possible, and is quite different from mixing the two fuels. That can result if a driver hooks to the wrong tanker, and disregards the tank # on his bill of lading.

I worked in the petrochemical industry for decades and have seen this happen a few times with other commodities. Quite different from contamination due to mixing. That can happen even with a dedicated 100LL fleet.

I don't k ow how it happened, but we ordered 100ll and got mogas

[neilpilot]

I once ordered #2 fuel oil and got gasoline. The driver swore it was fuel oil, and the BOL was for fuel oil, but fuel oil is UN1202 and the tanker was placarded UN1203.  Stuff happens.

[Bartman]

Could this be what happened to Brian Lloyd @CFII? I don't remember all of the details but I remember he aborted a flight because his engine was running rough, and actually I think it quit running as he was entering cruise flight. He returned and discovered fuel contamination, but if I remember correctly he stated all fuel going into his tanks went thru a filter. Perhaps he got the wrong kind of fuel, or was contaminanted with alcohol.  If the fuel was shipped in barrels from the USA it may have had alcohol in it  

I don't remember all of the details. Perhaps @CFII or @BCrystal can chime in ?

[mattbucy]

In my case, the fuel has become contaminated twice, first at the airport where I had tank work done and now a second time, two months later, with fuel from four different FBOs. I'd be astonished if four FBOs had laced fuel. Perhaps once compromised, it's toast and continues to leach.

[Mooneymite]

Thanks for publicizing this issue!

[Yetti]

https://www.pilotsofamerica.com/community/threads/100ll-contamination.105885/

[alextstone]

On 9/14/2017 at 6:02 PM, mattbucy said:

My mechanic made a call to PPG, the manufacturer of the sealants used on my reseal. They informed him that while the main sealant used, PR-1422, is insoluble in fuel, they have had reports recently of the recommended protective top coat sealant PR-1005-L dissolving in 100LL. They no longer recommend its use. 

@mattbucy I am in the process of repairing a fuel leak in my Mooney Bravo and I ran across your thread.  Do you or anyone else for that matter have any updates on whether this product is indeed indicated or not?  Did you get any testing done as you mentioned in one of your posts and if so, what was the outcome?  Third-hand oral communication just seems too weak to vet source of the problem.  I checked the PPG website and they still have it listed:

http://www.ppgaerospace.com/Products/Sealants/Specialty-Products/PR-1005-L-Buna-N-Slosh-Coating.aspx

Also, I cannot find any Service Bulletins, etc from Mooney or others warning against its use...

I'm going to try to get something in writing one way or the other from PPG...

Alex

 

[RobertGary1]

At sacramento executive the fuel company accidently mixed a bit of automotive fuel in the supply. They provided a free engine tare down for everyone who fueled. Cheaper than the liability. 
 

-Robert