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-----Original Message----- From: William R. Bayne [mailto:[EMAIL PROTECTED] Sent: Monday, October 24, 2005 10:45 PM To: Ed Burkhead Subject: WRB Re: WRB Re: [COUPERS-TECH] Cross-Country Glitches RLYTECH Hi John, According to the A-2 and A-2A Owners Manual, the description of the Aircoupe fuel system states: "The fuel tanks are interconnected by an overflow line which allows...fuel overflow from the wing tanks to the fuselage tank (caused by heat expansion)." Please describe how this could occur if Alon wing tank caps were vented? Would not the expanding fuel simply run out any vent onto the wing? I am presuming your words "original design" to mean "original Alon design. Since the "prototype" Alon was an uncompleted F-1A, I would expect it to have had the unvented wing caps common to all TC 718 airframes beginning with the Model E. Checking this out, my copy of the Alon Parts Manual calls for F-48183 wing tank filler caps (same as Forney). Forney's F-48183 drawing was functionally unchanged from the Ercoupe 415-48183 (unvented) cap. Please share with us any authoritative source that agrees with your statement "the original design had vented caps"? Alon Service Bulletin No. 8 does NOT "modify the vents". It does not show or mention any existing vent. A hole is drilled in a (presumably unvented) cap and a cotter pin inserted that holds a tube cap to the underside. Once this is done, the degree of "venting" expanding fuel then onto the wing (instead of up into the header tank) would depend on clearances. Alon SB 16 supersedes S.B. No. 8 and calls for installation of 610014-1 Wing Tank Filler Caps which, as you said, are unvented caps that re-configure the wing tanks to vent through the header tank. The reason Alon redesigned the unvented cap (new part #) is not obvious. Regards, William R. Bayne <____|-(o)-|____> (Copyright 2004) -- On Oct 24, 2005, at 11:40 AM, John Cooper wrote: > > At 06:11 PM 10/23/2005, you wrote: >> I could be wrong, but I thought Alons were designed with UNVENTED >> wing tank caps. > > The original design had vented caps. The first service bulletin > issued modifies the vents to help avoid fuel splashing out through > them. The second service bulletin supercedes the first and re > -configures the wing tanks to vent through the header tank and changes > to unvented wing caps. Mooney caps are also unvented. > > John Cooper > Skyport Services ============================================================================== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers-tech/
