X-Virus-Scanned: clean according to Sophos on Logan.com From: "Finn Lassen" Received: from vms173023pub.verizon.net ([206.46.173.23] verified) by logan.com (CommuniGate Pro SMTP 6.0.10) with ESMTPS id 7243871 for flyrotary@lancaironline.net; Wed, 29 Oct 2014 19:39:26 -0400 Received-SPF: pass receiver=logan.com; client-ip=206.46.173.23; envelope-from=finn.lassen@verizon.net Received: from [192.168.1.3] ([70.209.6.192]) by vms173023.mailsrvcs.net (Oracle Communications Messaging Server 7.0.5.32.0 64bit (built Jul 16 2014)) with ESMTPA id <0NE800B79CC58970@vms173023.mailsrvcs.net> for flyrotary@lancaironline.net; Wed, 29 Oct 2014 18:38:31 -0500 (CDT) X-CMAE-Score: 0 X-CMAE-Analysis: v=2.1 cv=GLe/yVJP c=1 sm=1 tr=0 a=MjltGZvVQTcIR3k+j6PqZg==:117 a=okrr6g_ZKtkA:10 a=o1OHuDzbAAAA:8 a=oR5dmqMzAAAA:8 a=-9mUelKeXuEA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=9iDbn-4jx3cA:10 a=cKsnjEOsciEA:10 a=be7PmAsAjO2OjH9ylIkA:9 a=wPNLvfGTeEIA:10 a=4PR2P7QzAAAA:8 a=ofS8y85dRt3k32kYQDMA:9 a=8LxmM5ANAj_uYmQm:21 a=_W_S_7VecoQA:10 Message-id: <54517A13.9040309@verizon.net> Date: Wed, 29 Oct 2014 19:36:51 -0400 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.28) Gecko/20120306 Thunderbird/3.1.20 MIME-version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: electric fuel selector valves References: In-reply-to: Content-type: multipart/alternative; boundary=------------070706050601000505090601 This is a multi-part message in MIME format. --------------070706050601000505090601 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit My most recent engine out landing was due to the previous owner's T-ing together the two tanks (RV-3B). Had 5 or more gallons left in the left tank. You simply must not T low wing tanks together! Finn On 10/28/2014 3:32 PM, Ernest Christley wrote: > > > > > >On the subject of backup fuel switching: If you have a ganged > mechanical valve, why bother with the electric one? :-) > > Two expensive three-way switches vs a single on-off valve. After > sending that last email, I realized it was pointless to make a > crossover for return side. Here is my analysis: > > You're flying along and at some point the electronic fuel goes tits > up. It is now stuck on one tank. You won't know until you go to > switch. You can: > > A) Do nothing. The fuel will continue to pull from the one tank. > This would be the sensible option if you're close to landing, or if > the tank has plenty of fuel. > > B) Open the crossover valve. This effectively tees the fuel supply > lines. This would make sense if the active tank was extremely low. > The high, inactive tank should now flow fuel into the low one. The > return line will still be routed to the low tank, also filling it back > up somewhat. It will not be possible to overfill the active tank > unless you opened the crossover prematurely. IE, open the crossover > valve to pull fuel from both tanks and return fuel to the active one. > You could even close the crossover once the active is half full. > > The part seems to be readily available from auto parts stores, so a > precautionary landing and replacement should be simple. > > > > --------------070706050601000505090601 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit My most recent engine out landing was due to the previous owner's T-ing together the two tanks (RV-3B). Had 5 or more gallons left in the left tank.
You simply must not T low wing tanks together!

Finn

On 10/28/2014 3:32 PM, Ernest Christley wrote:

>On the subject of backup fuel switching: If you have a ganged mechanical valve, why bother with the electric one? :-)

Two expensive three-way switches vs a single on-off valve. After sending that last email, I realized it was pointless to make a crossover for return side. Here is my analysis:

You're flying along and at some point the electronic fuel goes tits up. It is now stuck on one tank. You won't know until you go to switch. You can:

A) Do nothing. The fuel will continue to pull from the one tank. This would be the sensible option if you're close to landing, or if the tank has plenty of fuel.

B) Open the crossover valve. This effectively tees the fuel supply lines. This would make sense if the active tank was extremely low. The high, inactive tank should now flow fuel into the low one. The return line will still be routed to the low tank, also filling it back up somewhat. It will not be possible to overfill the active tank unless you opened the crossover prematurely. IE, open the crossover valve to pull fuel from both tanks and return fuel to the active one. You could even close the crossover once the active is half full.

The part seems to be readily available from auto parts stores, so a precautionary landing and replacement should be simple.

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