Long ago and far away....Sloshing Tanks

On a dark and stormy night....all this happened, more or less....in the early 80s, Van prescribed 2-3 coats of brushed-on PR1005L over Proseal before the rear baffle popped on. Then, 2-3 coats of sloshed PR1005L concentrated on the read baffle. In 1983,I followed the prescription up to the last bit. After I popped on the baffles, no leaks. So, I did not slosh. But there was plenty of PR1005L in the tanks on the ribs and stiffeners.

I began flying my 4 in June 1986. The years went by. For about 12-15 years, I used 92 octane no-lead auto in the right tank, about 5-6 tanks for every 100 LL left tank. The plugs were gorgeous and clean, and never any hesitation on power-up. But, about 2004, the right tank began to stain, and the stain grew into a damp weep over the years....So, I switched back to 100LL on both sides. In about 2011, the left started a little stain and then rapidly (over a year or so) started weeping. Not sure, but I suspect the aromatics in the auto fuel were just a little more aggressive versus the proseal....

In any event, this past winter, I finally bit the bullet and finished what I started by sloshing the baffles. I know the Randolph story, but it's not buna. I have never heard any criticism of PR1005L, and not because everyone who used it is dead. Certainly, I have seen no evidence of peeling/delamination in my tanks, and the Weep No More guys seem to use a similar product over proseal on their Mooney tanks. So, in 2012, I sloshed with PR 1005L. 1 pint total, 1/2 in each tank in two separate coats. I kept constant pressure air feed in my fuel pick-up and vent lines and deem this an absolutely worthwhile precaution since it keeps the syrup from blocking anything. Result? no visible blockage; no fuel flow restrictions at any power setting; no evidence of flake into gascolator or visible thru fillers (the new coat is sticking just like the 30 year old coats); and.....dry, clean tanks...whew!

What this is not: an engineering study or recommendation or warranty or anything like that. No doubt, someone can kill himself with this stuff, and, if enough people use it, someone will. But, seems to be working for me, and certainly was the prescription, oh, so many years ago.

Here is a link to the product: http://www.ppg.com/coatings/aerospace/sealants1/pr_1005L.pdf

MTCents, John N95JF

A screaming comes across the sky. - Thomas Pynchon

I think most of the peeling problems could likely be traced back to inadequite surface preperation. Slosh sealants and brush on 'C' class sealants require the same prep as you do for the standard 'B' class sealants, simply pouring them in and "sloshing" the compound around is not conducive to long term adhesion.

If I were going to use a brush top coat (on a new tank), I would go with a 'C' class sealant of the same type (890 has a 'B' and 'C' class) catagory rather than the 1005.

Walt: Thanks for your comments. Are you aware of any peeling problems with PR1005L? I have not detected any, but always good to know if you have something to offer.

Re surface preparation: Dick prescribed cleaning with naptha and a lint-free rag, nothing else. Naptha, a solvent, is a feedstock for...gasoline...my guess is running, in my case, thousands of gallons of 100LL thru the tank would be adequate for removing trace oils that would reduce cohesion. In the event, no evidence of delam in my plane, yet anyway.

Not sure what to make of the "surface prep" comment. Have heard of "scotchbrite" scuffing, etc.....never mentioned in the old days, and, again, unaware of any issues in that regard. I presume some of us would have had something to share if it was an issue (certainly would be at construction when you have all kinds of contaminants to clean up, but in an operational tank, there ought be none).

Finally, not sure what to make of the "B" and "C" class product comments. Dick prescribed PR1005L, and it sloshes just fine, but maybe there is room for improvement....That said, my personal rule is that I deviate from Dick's design only on good, demonstrable evidence.

I am aware that there are lots, loads and an abundance of issues with Randolph and possibly other sloshes, and your comments may be based on that collective experience. Personally, I hope to die in my sleep, so I am not leaving the ground in a Randolph sloshed plane. Period. That said, I know of no evidentiary basis to extrapolate those issues to PR1005L that may only share with Randolph the word "slosh". Tailwinds, J