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Ed
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-----Original Message-----
From: William R. Bayne [mailto:[EMAIL PROTECTED]
Sent: Wednesday, March 09, 2005 9:39 PM
To: Ed Burkhead
Subject: WRB Re: [COUPERS-TECH] Tern(e)plate tanks
From: William R. Bayne [mailto:[EMAIL PROTECTED]
Sent: Wednesday, March 09, 2005 9:39 PM
To: Ed Burkhead
Subject: WRB Re: [COUPERS-TECH] Tern(e)plate tanks
RLYTECH (WRB via Ed Burkhead's computer-I can't post directly)
Please send responses directly to the list or to me, Bill Bayne @
<[EMAIL PROTECTED]>
Hi Bettina & Bob (WRB speaking),
Yours is a fascinating question that hasn't yet been addressed.
I went to the Parts Manual, p. 26. It says the fuel system is the same for Ercoupes Serials 113-2623 (which would mean stainless tanks made to fill orders for replacements of the ternplate tanks originally fitted to these serial numbers would fit your bird).
Since there is a big difference in the design required for the airframes Serials 113-812 (with the MLG mounting on the front of the main wing spar) and later Ercoupes, I took a look at Serial No. 404. We know that the original production ternplate wing tanks of 9 gal. capacity had to fit around the MLG on the front of the spar, and were so designed. I have speculated that the stainless tanks manufactured as replacements probably merely noted a change of material on the same drawings (that's how I would have done it).
Now pretend you're Fred Weick (humor me) in March of 1946. You're producing Ercoupes as fast as you can stamp them out, and a change to the main landing gear is implemented into production to ease a transition to retractible gear (one already in design that will be completed in mid-September for testing.).
The 9 gallon ternplate tanks in production fit the new arrangement just fine (if you don't cut the bottom hole to clear structure no longer there) and you may have a gazillion of them already in stock. Although production could be simplified (and capacity increased) by eliminating the "jog" in the back of the tank, should you give priority to changing the existing tank? It seems obvious that Fred's/Erco's answer was no.
If you DO still have original ternplate tanks, and they remain servicable, Erco long ago reached the decision not to require replacement. They figured that those tanks that had not cracked in the first year or two of operation (which was the great majority) would provide satisfactory service indefinitely.
Certainly the many years since passing has vindicated this view, and there was never an AD requiring replacement. A leak in a ternplate tank can be soldered!
I think Ercoupe Service Memorandum 31 is unintentionally misleading in it's wording. Par. 3 begins quite specifically stating, "Subsequent to Serial Number 2623..." thusly inferring that all which follows is similarly limited. It would now appear the last two sentences were, in fact, general statements meriting a separate paragraph to be so read:
"A description of both (ternplate and aluminum tanks)...will be discussed... They will
be referred to as a 'ternplate tank' and 'aluminum tank,' as the case may be, even though ternplate tanks have been superseded by stainless steel for replacement purposes."
Additionally, Par. 5 begins with what I believe to be a general statement:
"Tanks fabricated of stainless steel are being shipped on parts orders in lieu of the ternplate tanks. The stainless steel tanks are interchangable with the ternplate tanks."
The subject is then changed to which Ercoupes can be modified to take aluminum tanks, which is the more restricted serial range of 813-2622 and specifics are in ESM-39.
So, to answer your question, if you can find them (Univair no longer lists replacement tanks Pt. No. 40803L & R for sale), any stainless 9 gal. tanks should fit your bird just fine.
I have seen no evidence of stainless steel wing tanks produced in any other size, nor of aluminum tanks ever being produced by the factory to fit Ercoupes Serials 112 - 812.
That is not to say that an individual or two could not have had a set custom-made (or modified from production or replacement aluminum tanks). It wouldn't be exactly rocket science to do so.
Regards,
William R. Bayne
<____|-(o)-|____>
(Copyright 2004)
--
On Mar 9, 2005, at 6:59 PM, Bettina Latty & Bob Pionteck wrote:
Hi All........... and interesting reading.
Our 'Coupe is S/N 719 and I believe that we have the original style wing tanks (header as well). Question here is, since we have the original style of landing gear (tube steel mounted to the front of the spar) can we use any other style of tank as a replacement?
Food for thought.
Maybe I'll drain and measure the quantity of fuel in the tank on the next 25 hr check as well.
Cheers
Bettina & Bob
CF-LAV
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