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03-29-2016, 11:29 AM
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Join Date: May 2014
Location: KBVY Massachusetts
Posts: 1,100
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Quote:
Originally Posted by Toobuilder
I have not read every post, but have you considered doing a quick ground run on the right tank to verify it is feeding or not, and if so, take off on the left tank (which you KNOW is feeding), climb to a safe altitude over the airport and then switch to the right? You should have a definitive answer in about 5 seconds.
After that you can evaluate changing out the fuel selector, but if the right side feeds at least you can use the airplane again.
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I thought of that but:
what if the selector itself is busted and doesn't really switch from the left tank to the right tank but stays on the left no matter how I have the knob set?
__________________
Flying RV-8 N880BC
2019 Dues - happily paid.
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03-29-2016, 12:21 PM
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Join Date: Aug 2015
Location: Novi, MI
Posts: 107
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Please excuse me, if my post sounds harsh, but this topic makes me really nervous. Firstly, because the builder thought that it might be a smart idea to install a fuel selector with a ‘both’ setting (what other brilliant ideas did he have?). Secondly, because this didn’t strike the OP as odd. 
Frankly, I also wonder about the leap from believing that a ‘both’ setting is fine to some fancy testing of the fuel system.
This is what I would suggest:
- Visually inspect / confirm the type of the fuel selector and the fuel system layout.
- Remove one end of the fuel hose somewhere after the fuel pump and hang it into a gas can.
- Turn on the auxiliary pump, test all positions of the fuel selector, confirm that they are in accordance with your observations and measure the flow rate (how long does it take e. g. to fill 3 gal. into the gas can and calculate the hourly flow rate based on that). This will also allow you to confirm your expectation regarding the fuel levels with a dip stick (one side should remain unchanged, the other should have dropped).
I strongly doubt that there is anything wrong with your fuel selector valve. Most likely, it is simply the wrong type which had been installed.
__________________
* Flying Mooney M20E
* RV-10 kit on hold
Last edited by Oliver : 03-29-2016 at 12:26 PM.
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03-29-2016, 12:45 PM
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Join Date: Mar 2005
Location: Dallas area
Posts: 10,768
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PLEASE!!!!!!!!!!
PLEASE change that valve to the proper one!
Do not fly this aircraft until done!
__________________
Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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03-29-2016, 12:48 PM
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Join Date: May 2014
Location: KBVY Massachusetts
Posts: 1,100
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Quote:
Originally Posted by Oliver
Please excuse me, if my post sounds harsh, but this topic makes me really nervous.
If the post makes you nervous imagine my feeling when a system that worked just fine for months suddenly....behaved differently.
Firstly, because the builder thought that it might be a smart idea to install a fuel selector with a ?both? setting (what other brilliant ideas did he have). Secondly, because this didn?t strike the OP as odd.
Sorry I'm not omniscient but I am here to learn. And I learned something.
Frankly, I also wonder about the leap from believing that a ?both? setting is fine to some fancy testing of the fuel system.
Not sure what "leap" you are talking about. The system worked fine until one day it didn't (tanks were never lower than half full at any time BTW). In other words - something changed. THAT is a red flag to me.
After making the original post, I've learned the dangers of a BOTH setting if one tank is low. I've digested that and have moved on to wanting to assess the fuel system.
The fact that it no longer worked as it did was pretty unnerving and now, to me, the OP, this calls into question the fuel system rigging.
The "leap" is because of what you yourself just suggested: what other brilliant ideas did the builder (not me) have? Just how DID he rig that fuel system? Well I'd like to test the fuel system, and, at the same time, determine how it is built. And do it before I fly again - as I've said..
If you are talking about some other leap I'm not sure what that is.
This is what I would suggest:
Your list has already been suggested and corroborated by other posters and is what I'm going to do.
I strongly doubt that there is anything wrong with your fuel selector valve.
Perhaps you'll find a way to pardon me for not just making that assumption - especially given your concern about "other brilliant ideas".
Most likely, it is simply the wrong type which had been installed.
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Your post doesn't strike me as harsh.
It does strike me as yet another example of beating a very dead horse with regard to the BOTH setting and the fact that the selector has that setting.
Well I suppose everyone has to get their two cents in about that, and tell me what they would do with regard to signing off my airplane if they were inspecting it and so forth.
In fact I long ago, in this thread, made my decision about the selector.
What does not seem simple to me - what I need to figure out and hope to obtain aid from people in this forum - is figuring out the best way to test the fuel system and determine it's rigging. THAT is where my focus is in this thread.
__________________
Flying RV-8 N880BC
2019 Dues - happily paid.
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03-29-2016, 01:54 PM
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Join Date: Jan 2005
Location: Spring, TX
Posts: 233
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Quote:
Originally Posted by Saville
What does not seem simple to me - what I need to figure out and hope to obtain aid from people in this forum - is figuring out the best way to test the fuel system and determine it's rigging. THAT is where my focus is in this thread.
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I think it was mentioned before but lost in the shuffle. Disconnect the fuel line to the carb/servo and redirect it to a suitable container. Then turn on the boost pump and cycle thru the valve positions. You can measure the fuel drop in the selected tank against the fuel output to the container to confirm where it's coming from. Worst case is you have to cap off the lines between the valve and tank to assure no flow from that tank. You could do that at the valve or at the wing root.
While you're at it you can also do the max attitude flow test. Put the tail in a hole/ditch and/or jack up the nose to an attitude well above stall and measure the flow rate from each tank with the boost pump. It needs to be greater than the max fuel consumption at SL WOT. There's more specifics in the construction manual (or at least there used to be).
__________________
Greg
1950 Navion - flying
RV-6 - 18 yrs and 99.5% done
1940 Rearwin Cloudster project next
4 L-2 projects on deck
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03-29-2016, 02:51 PM
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Join Date: Jul 2013
Location: US
Posts: 2,251
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Quote:
Originally Posted by Saville
What does not seem simple to me - what I need to figure out and hope to obtain aid from people in this forum - is figuring out the best way to test the fuel system and determine it's rigging. THAT is where my focus is in this thread.
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1. Open up/remove the covers over the valve
2. Remove any covers over the fuel lines in the cockpit
3. Look with Mark I Eyeballs at which tank is connected to which input on the valve.
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03-29-2016, 03:13 PM
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Join Date: Jan 2005
Location: NC25
Posts: 3,507
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Quote:
Originally Posted by Oliver
Please excuse me, if my post sounds harsh, but this topic makes me really nervous. Firstly, because the builder thought that it might be a smart idea to install a fuel selector with a ?both? setting (what other brilliant ideas did he have?). Secondly, because this didn?t strike the OP as odd. 
Frankly, I also wonder about the leap from believing that a ?both? setting is fine to some fancy testing of the fuel system.
This is what I would suggest:
- Visually inspect / confirm the type of the fuel selector and the fuel system layout.
- Remove one end of the fuel hose somewhere after the fuel pump and hang it into a gas can.
- Turn on the auxiliary pump, test all positions of the fuel selector, confirm that they are in accordance with your observations and measure the flow rate (how long does it take e. g. to fill 3 gal. into the gas can and calculate the hourly flow rate based on that). This will also allow you to confirm your expectation regarding the fuel levels with a dip stick (one side should remain unchanged, the other should have dropped).
I strongly doubt that there is anything wrong with your fuel selector valve. Most likely, it is simply the wrong type which had been installed.
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I once was a DAR that would NOT issue the Special Airworthiness Certificate to an RV till after the Fuel Selector Valve was changed to one that did not have a BOTH position. It is my belief that it is UNSAFE to have a fuel valve with both position in the present low wing fuel tank RVs. I would not sign off the once a year Condition Inspection as being in a condition for Safe Operation with a BOTH position fuel valve on a low wing fuel tank Experimental aircraft.
__________________
Gary A. Sobek
NC25 RV-6 Flying
3,400+ hours
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.
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03-29-2016, 03:51 PM
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Join Date: Mar 2005
Location: Dallas area
Posts: 10,768
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Quote:
Originally Posted by RV6_flyer
I once was a DAR that would NOT issue the Special Airworthiness Certificate to an RV till after the Fuel Selector Valve was changed to one that did not have a BOTH position. It is my belief that it is UNSAFE to have a fuel valve with both position in the present low wing fuel tank RVs. I would not sign off the once a year Condition Inspection as being in a condition for Safe Operation with a BOTH position fuel valve on a low wing fuel tank Experimental aircraft.
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I'm STILL a DAR. I have certificated over 800 aircraft. and like Gary, I would never sign off an RV with a "Both" position on the fuel selector.
__________________
Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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03-29-2016, 03:52 PM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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An element of paranoia has crept into this thread.
There is nothing unsafe about the BOTH position of this valve. It MAY become unsafe if it is used but even then the airplane won't fall out of the sky.
There are a number of switches in every aircraft that create an unsafe situation if used in flight. Guess what happens if the ignition switch is moved to OFF or the mixture is pulled to OFF? Placards are even not required for these obvious unsafe situations.
It would appear this aircraft was built with some care. I would be most reluctant to condemn the builder, perhaps several EAA tech advisors who frequently inspect before certification, or the DAR (or perhaps FAA inspector) who certified it.
If the valve gives one night mares, change it. My 2 cents worth is I would have no qualms whatever about flying this aircraft with or without a placard to not use the BOTH position.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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03-29-2016, 04:00 PM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Where is that "like" button?
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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