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From: William R. Bayne [mailto:[EMAIL PROTECTED]
Sent: Wednesday, December 21, 2005 1:09 AM
To: Ed Burkhead
Subject: WRB Re: [COUPERS-TECH]
RLYTECH
Hi Richard,
Sorry for the delay, TECH list had dropped me. Tell your IA to believe the Ercoupe Parts Catalog. It's authoritative, if not fully informative in the manner you need.
On earlier Models there was only a single such line between one wing tank and the header tank, and equalization of excess fuel bypassing from the header tank back into the wings had to equalize via the (lower) line directly between the tanks from which the fuel pump draws. Since only one of the wing tanks could vent through this line, the factory fitted vented wing tank caps for systems so plumbed, but there were some problems in the field with this arrangement.
From the first Model 415-D (see diagram in F.A.A. Approved Airplane Flight Manual) unvented caps were fitted in hopes of cutting down the tendency to lose fuel from wing tanks fully filled. Each wing tank has a return/vent line rising to a tee which goes into the fuselage tank. This allows each wing tanks so piped to vent to the fuselage (header) tank. The absence of this diagram from the Parts Book fosters such misunderstandings.
With so many years having passed, and tanks from one Ercoupe used in another almost anything could be found in a given example, withour regard to serial number. So "bottom line" is if each wing tank has a line from its upper level that allows venting into the header (fuselage) tank, use unvented caps. If there is but a single wing tank so vented, use vented caps. (and if the tanks and plumbing don't properly conform to your model, make sure the revision(s) is/are properly documented and logged by someone of appropriate authority.
Regards,
William R. Bayne
<____|-(o)-|____>
(Copyright 2004)
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On Dec 18, 2005, at 11:26 PM, Richard okeby wrote:
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Hey Gang - My IA is squawking about my wing tank caps being unvented. I know this subject has been tossed around before but the archives don't really answer this question. Have I missed a service bulletin or A.D. that requires a change to vented caps? The parts list shows unvented caps for my 415 C/D serial # - 4667. Can anybody tell me why some coupes have them and some don't, and why?
Also, exactly how do the wing tanks vent? It looks like somehow they vent thru the fuse tank, but I gotta argue this one with him because he wants me to drill the caps I have, which have been flying unvented a long time. I'm thinking I've got the right set-up here, but I need to straighten this fellow out. (and me too) Thanks for any info -
Richard Rokeby N3966H
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