---------------------------------------------------------- Kitfox-List Digest Archive --- Total Messages Posted Tue 06/26/12: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:05 AM - Re: Engine out..deadstick landing required..question on header t (rawheels) 2. 04:51 AM - Re: Re: Engine out..deadstick landing required..question on header t (Walter O'Neal) 3. 09:40 AM - Re: Re: Engine out..deadstick landing required..question on header t (Guy Buchanan) 4. 03:47 PM - Re: Engine out..deadstick landing required..question on header (mikeperkins) ________________________________ Message 1 _____________________________________ Time: 04:05:23 AM PST US Subject: Kitfox-List: Re: Engine out..deadstick landing required..question on header t From: "rawheels" Kitfox Service Bulletin #29 says to get rid of the fuel selectors, because they can contribute to fuel starvation: http://www.kitfoxaircraft.com/support/service_bulletins/sb29.htm Read this topic online here: http://forums.matronics.com/viewtopic.php?p=376622#376622 ________________________________ Message 2 _____________________________________ Time: 04:51:36 AM PST US From: "Walter O'Neal" Subject: RE: Kitfox-List: Re: Engine out..deadstick landing required..question on header t amen! Walter O'Neal Director of Technical Services Tideland E.M.C. 252-944-2409 Dir. 252-943-8265 Cel 1-800-637-1079 -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of rawheels Sent: Tuesday, June 26, 2012 7:05 AM Subject: Kitfox-List: Re: Engine out..deadstick landing required..question on header t Kitfox Service Bulletin #29 says to get rid of the fuel selectors, because they can contribute to fuel starvation: http://www.kitfoxaircraft.com/support/service_bulletins/sb29.htm Read this topic online here: http://forums.matronics.com/viewtopic.php?p=376622#376622 Confidentiality Notice: The contents of this electronic message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, copy, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please contact the sender by replying to this email and destroy all copies of this message. ________________________________ Message 3 _____________________________________ Time: 09:40:37 AM PST US From: Guy Buchanan Subject: Re: Kitfox-List: Re: Engine out..deadstick landing required..question on header t On 6/26/2012 4:04 AM, rawheels wrote: > Kitfox Service Bulletin #29 says to get rid of the fuel selectors, because they can contribute to fuel starvation:http://www.kitfoxaircraft.com/support/service_bulletins/sb29.htm > Hmmm. Wonder how they do that? After all, we know that "Valves don't kill people. People kill people." ;-) Guy Buchanan Ramona, CA Kitfox IV-1200 / 912-S / Warp 3cs / 500 hrs. and grounded Now a glider pilot, too. ________________________________ Message 4 _____________________________________ Time: 03:47:44 PM PST US Subject: Kitfox-List: Re: Engine out..deadstick landing required..question on header From: "mikeperkins" Sorry to hear about the outcome of your glider experience. Not fun, and expensive. A power loss associated with switching tanks would only occur if the header tank contained mostly air. That could happen if the header vent line were obstructed. True that the head pressure comes from the fuel tanks, not the header tank. But wing tank head pressure is not always reliable. A lot of high-wing aircraft do not have a header tank. In a Kitfox, the purpose of the header tank is to provide fuel when both wing tanks are unported (during slips and negative pitch with low fuel, etc.). Also, without a header tank with two ports, a T would be necessary. However, T's are notorious for creating vapor lock (a bubble lock) when located where head pressure is very low, and so the header tank eliminates the need for a T. In any case, the intent of the header tank behind the seat is not in itself to supply head pressure. The folding-wing design contributes to the tendency for the hoses to have a rise near the wing hinges which are prone to vapor locking. And thus the header tank also provides insurance against temporary vapor locking in those humps and gets rid of the need for a T. Being a Model I builder, before Service Bulletin #29 was written I became aware that some builders were mounting their fuel valves conveniently to the fuselage structure adjacent to the wing tanks, nearly level with the fuel tank outlet, and in some cases even above the outlets. With practically zero head pressure here, we eventually concluded there was the possibility for air to be trapped in the valve innards as well as in a hose hump. Since fuel is notorious for not liking to be pulled by a pump and for not overcoming vapor locks, aka ever-expanding fuel bubbles (because of its characteristically-high vapor pressure), the pump engine pump was not able to draw fuel. So if both valves or both fuel hose humps were vapor-locked, no fuel would get to the engine. (This is one of several reasons the EAA and FAA had to prove back in the 80s that auto fuel would work in certificated aircraft and why there are not mogas STCs for all aircraft. But all gasoline, including 100LL, has some vapor pressure - it's just that mogas comes equipped with more of it.) The answer for the Kitfox fuel flow problems was to put the valves down much lower and to prevent any rises in the hoses and fuel lines prior to the header tank. It was discovered after SB #29 was written that this was ok to do, but the SB remained in effect, probably for liability reasons. My wing tank valves for 400 hours have been about 3 above the seat-backs, no fuel problems. It is not convenient for in-flight operation; the intention was mostly for fueling and de-fueling purposes anyway. This location reduces the possibility for vapor lock because there is a 20 drop from the wing tanks fuel outlet before reaching the valve. And care was taken to avoid fuel hose humps in the hinge area. For flight-emergency purposes, I installed a master fuel valve on the floorboard under the left door near the carry-through truss. Running a gravity fuel supply test is always good idea, but it does not account for vapor lock caused by combinations of flight conditions, differences in the gasoline used, and high temperatures, etc. It is best to put fuel pumps near the tanks so that fuel is pushed, rather than pulled, using perhaps a pair of Facet pumps. Low wing aircraft would do best this way, obviously not a Kitfox issue, but something worth mentioning. If the selector valves are up high, they should be relocated lower, but it is ok to have them as long as there is a significant fuel-system drop before them. And the vent line should be checked for blockage. Obviously filters and fuel lines in general should be checked. A mud dauber when the lines are apart for maintenance can cause havoc. Also, a filler cap vent blow-test should be a checklist item. A pair of Facet pumps hear the tanks would also overcome a variety of fuel-system sins. Hope this helps. -------- Mike Perkins EAA TC/FA Havana, Illinois Model I, 532, B gearbox, GSC prop Read this topic online here: http://forums.matronics.com/viewtopic.php?p=376681#376681 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kitfox-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kitfox-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kitfox-list Browse Digests http://www.matronics.com/digest/kitfox-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.