Hi Lee,
Ercoupe Service Memorandum No. 33 issued in 1947, acknowledges that
tanks of riveted construction had
evidenced seam leakage and/or seepage in the field. Sloshing was the
ERCO-recommended method of
repair to the then-new aluminum fuel tanks. Only the seam areas were to
be sloshed. "It is not necessary
or desirable to cover the remaining surfaces..."
On January 15, 1954, ESM 33A changed the recommendation from 3M EC-570
to EC 776. Done in the
prescribed manner by a professional, these sloshes served the intended
purpose well.
By the late eighties the formulation of autogas had changed to
"unleaded" and to achieve the higher octane
necessary for modern autos now had much in common with generic paint
thinners. The phaseout of 80/87
avgas and introduction of ethanol to auto fuels caused slosh compounds
applied in the past (and previously
serving their intended purpose satisfactorily) to dissolve or come
loose in pieces of varying size.
Randolph came out with various compounds, at least one of which was
supposedly safe to use with auto fuel.
Unfortunately, gasoline has never been a "blend" of compounds that is
stable in formulation. The very process
of refining petroleum produces gasoline as a by-product, the volume and
consistency of which can be varied to
a considerable degree but never eliminated; which was further blended
as necessary to meet (rather broad)
specifications. Some of us are old enough to remember "gas wars" when
too much gasoline filled storage tanks.
I believe our tank expert, John Wright (and probably the people that
make their living sealing Cherokee tanks)
uses Pro Seal in tank seams before re-riveting. Terneplate and
stainless steel tanks have soldered seams that
should be repaired by soldering. Some aluminum tanks have welded seams
that should be repaired by welding.
Perhaps it would be more accurate to state that there is no "sloshing
compound" in current production that
the manufacturer or Univair has approved for use in Ercoupe tank seams.
That said, I find it hard to believe
that in all these many years of "better living through chemistry" ;<)
there are no space-age compounds suitable
and safe to use today for simple seam sealing...seemingly a "minor
repair".
A final point worth making. Wing tank finger strainers exist (or
should). These are describe on page 48 of the
Ercoupe Service Manual, and actually illustrated on page 46, Fig. 31.
Unfortunately the same cannot be said of
fig. 32, 33 or 34. These should be removed before sloshing; then
cleaned/replaced as appropriate.
Best regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2009)
--
On Apr 18, 2009, at 11:57, [email protected] wrote:
In as much as no one responded to my question as to what use sloshing
compounds are, I assume there is no good use for sloshing compounds..
Lee
