|
-
POSTING RULES

-
Donate yearly (please).
-
Advertise in here!
-
Today's Posts
|
Insert Pics
|

10-05-2015, 11:07 AM
|
 |
|
|
Join Date: Jul 2013
Location: US
Posts: 2,251
|
|
Quote:
Originally Posted by F1R
Some selector valves are quite easy to select off by accident.
|
This is one of those times when experimentals are well advised to do things the certified world does:
FAR 23.995
g) Fuel tank selector valves must?
(1) Require a separate and distinct action to place the selector in the ?OFF? position; and
(2) Have the tank selector positions located in such a manner that it is impossible for the selector to pass through the ?OFF? position when changing from one tank to another.
E.g., the Andair valves require lifting up on a central knob while simultaneously turning the valve...an action that cannot be done accidentally.
|

10-05-2015, 11:19 AM
|
|
|
|
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
|
|
I switch every 30 minutes based on the reminder from GRT without turning the boost pump. If I am very close within 10 minutes of landing and the timer goes off, I will ignore it and will not switch.
For long trips, I follow the above procedure only will try to keep one tank a bit fuller than the other, so I may skip one time switching. As I get closer to my destination, I will switch to the tank that is a bit fuller. Also I will keep in mind left or right pattern so I am on the tank that the opposite side of my turn in the pattern in hopes of not to suck air if the fuel rushes to the other side of the tank in a sharp turn in the pattern. But generally I will avoid getting so low on the fuel. I believe my longest leg was just shy of 5 hours and when I landed I still had 11G (I added about 31G of fuel)
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
|

10-05-2015, 11:24 AM
|
|
|
|
Join Date: Jun 2007
Location: new iberia la
Posts: 768
|
|
Tank Switching
If taking off with full fuel I fly 45 min on first tank and switch about every hour after that with interval adjusted so tank switch happens in gliding range of a airport or suitable landing spot. I flight plan to have last tank switch at top of descent. I really avoid switching tanks before takeoff or a low altitude. After landing I switch to tank that will be used on next takeoff and set takeoff trim at the same time.
Don B
RV 9 rebuild in progress
|

10-05-2015, 11:48 AM
|
 |
|
|
Join Date: Jul 2013
Location: US
Posts: 2,251
|
|
Quote:
Originally Posted by RV7ator
Couple of posters say they switch just before take off.
That's a very bad idea. Particularly if you've just added fuel.
I discovered two MINUTES at cruise power settings is required to consume fuel downstream of the valve in a -7 before fuel from a newly selected tank reaches the engine. At the trickle rate of consumption prior to take-off you may choose a tank with problem fuel that won't show up until you're a few feet off the ground.
Before start-up, select the tank you're going to use for the first 30 minutes of flight then don't mess with it until you're within a short distance of a suitable landing area. Thereafter, I keep a simple log on a scrap of paper showing the time and which tank when I switch on the quarter hours.
John Siebold
|
This is an interesting discussion. A couple of centuries ago, during my primary and instrument training, I was taught by several instructors and check pilots to start up and taxi out on one take, then switch to the other tank and do the run-up and take-off, thus ensuring good fuel flow on *both* tanks.
I can see the logic of not switching until after take-off, I guess...although it might be disconcerting to find out *in flight* that you can't get fuel from one tank. Out of curiousity, who does which method here? (N.B., I'm not likely to change what I've been doing for all these years, but just curious about the thinking).
|

10-05-2015, 11:58 AM
|
 |
|
|
Join Date: Feb 2015
Location: Fort Worth
Posts: 527
|
|
When I'm flying certificated planes I taxi on the lower tank, switch to the fuller tank before runup and leave it there until the first switch (bottom of the hour)
For high wings I start up on left, switch to right while taxiing, and then go both before the runup and then I don't touch it again.
This thread has me questioning... are there fuel selector valves out there I should be avoiding (and making sure I don't already have installed)
__________________
Rob
RV-6A (Purchased)
2020 Dues Paid, of course
|

10-05-2015, 02:25 PM
|
 |
|
|
Join Date: Feb 2005
Location: 20km outside of Zurich, Switzerland
Posts: 468
|
|
Andair valve is different
The Andair valve is different in two cases:
1. as allready mentioned by RV7A Flyer
Quote:
|
E.g., the Andair valves require lifting up on a central knob while simultaneously turning the valve...an action that cannot be done accidentally.
|
2. If you switch from LEFT to RIGHT: In the beginning of valve rotation, it opens the canel to the right tank. Then for a part of rotation, both tanks are feeding, then in the last moment of rotation, it closes the left and only the right is feeding.
So, if you are not absolutley dry on one tank, there should not happen anything bad, if you would rip of the handle or the shaft brake away. Which would be very very unlikely. The andair valves are so smooth. If it is going strong, as on many GA planes, you should investigate to find out why and maybe replace them, before something bad happen.
But if you are using the original, Vans brass vauchet, then it is a really different animal .... thats the reason Andair is selling so much of there valves! Paul got the lesson and had quit a bit of luck on his side. Veri kind he shared his experiance with us.
__________________
Dominik
RV-7A, TMX-IO-320, FM-150, Sensenich FP
Flying since 28. April 2016
|

10-05-2015, 03:07 PM
|
 |
|
|
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
|
|
Quote:
Originally Posted by swisseagle
So, if you are not absolutley dry on one tank, there should not happen anything bad, if you would rip of the handle or the shaft brake away.
|
This is only true to a point.... Once one of the tanks ran dry the fuel pump would likely start sucking air into the system through the empty tank (that is why we do not use a fuel selector with a both position on a low wing airplane).
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
|

10-05-2015, 03:21 PM
|
 |
VAF Moderator / Line Boy
|
|
Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
|
|
Quote:
Originally Posted by swisseagle
Paul got the lesson and had quit a bit of luck on his side. Veri kind he shared his experiance with us.
|
Always happy to share our "Lessons Learned" Dominik!
In this case, the lesson was not really about fuel valves - it was that we never rely on "Luck" - we rely on preparation so that WHEN a failure happens, it is no big deal. We had a good landing site under us for a reason and we used it when we needed it.
Oh, to the point of this thread- since we now live in a mountainous part of the country, I always take a look around before switching tanks - and if I can put myself in a better position with regards to a landing opportunity by delaying a switch, I do so. Why not set yourself up for an easy emergency case when you can?
Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
Last edited by Ironflight : 10-06-2015 at 03:31 AM.
|

10-05-2015, 10:31 PM
|
 |
|
|
Join Date: Aug 2007
Location: Wichita Falls, TX
Posts: 2,182
|
|
In my 6, when taking off with both tanks full, since I'm most often solo I take off on the left tank and run for 15 minutes and begin switching tanks every 30 minutes thereafter. The takeoff and climb to cruise altitude burns fuel faster than level cruise and my technique helps to lessen having a heavy wing due to fuel level imbalance. I've been doing the same thing since the days of flying my old Cherokee 140 which had no autopilot to artificially keep the wings level for me :-)
I always turn on the electric pump when switching tanks... and keep an eye on the fuel pressure gauge too, just like I did in the Cherokee. Old habits are hard to change.
__________________
Neal Howard
Airplaneless once again...
|

10-10-2015, 07:59 PM
|
|
|
|
Join Date: Sep 2013
Location: Olds, AB
Posts: 83
|
|
I use a similar 1/2 hour for take off, followed by 1 hour switches to minimize the frequency of tank switches. This keeps the plane in reasonable balance, and minimizes the small risk of valve failure while switching. I don't use the auxiliary fuel pump if I have lots of altitude.
As part of testing, I purposely ran each tank dry while 5000' over the airport (separate flights) to check fuel gauge calibration and re-start performance. In level flight, my plane takes about 8 long seconds to recover from fuel starvation without using the auxillery pump, and about 3 seconds to recover with the pump. I can cruise about 8 minutes after the calibrated EFIS gauges read zero before it gets quiet, HOWEVER, I can starve the engine with 5 gallons in a slip. As a result, I like to keep a minimum of 10 gallons in my left (primary) tank for landing, and let my right tank run to the onset of starvation before the last enroute switch.
I run premium Mogas in my right tank, and avgas in the left, which is why I consider the left tank my "primary". Both tanks work the same, but I can get vapor lock on Mogas on warm days if the auxillery pump is not running. When away from home I run straight avgas, which lets me test the left tank to the onset of starvation. (Full starvation occurs several seconds after the onset)
I would encourage you to test each of your tanks to starvation under controlled conditions. The knowledge lets you make longer legs with peace of mind, may prevent an uneccesary precautionary landing, and avoids the dangerous situation of landing with two low tanks. I dont use this procedure to shave my fuel reserve, it just ensures I have a truly usable reserve when I land.
Jay
__________________
RV7-A
C-FXPT
IO-375, Catto, Electroair, Skyview
400 hours
|
| Thread Tools |
Search this Thread |
|
|
|
| Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -6. The time now is 08:51 AM.
|