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06-22-2017, 12:10 PM
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Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,145
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Quote:
Originally Posted by 160kt
If the pilot understands his fuel system as he is supposed to then there is no surprise. He will know what happened and what is to be done to correct.
What's the big fear here?
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The answer is in your question. Too many pilots do not fully understand their own fuel system, and when that becomes problematic it all too often becomes fatal. This is especially true of non-builder pilots that have never been exposed to the fuel plumbing.
__________________
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2020 dues paid 
N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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06-22-2017, 12:41 PM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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I got an idea. How about we follow the plans!
__________________
Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
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06-22-2017, 01:37 PM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by JonJay
I got an idea. How about we follow the plans!
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If we did that, there would be no Rockets!
__________________
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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06-22-2017, 01:46 PM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by 160kt
...What's the big fear here?
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As one who has been down this road before on VAF, I'll say that I agree in principle that a "both" selector is not inherently dangerous if managed properly. That said, that level of management is a human factors nightmare (strike 1), is nonstandard among a group of nonstandard airplanes (strike 2), and the consequences of getting it wrong is extremely hazardous (strike 3).
Yes, this forum has a distinct "...but think of the children!..." vibe to it, but in this case it's probably justified. There are plenty of non builder owners out there and there's no standardized POH to turn to for guidance.
__________________
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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06-22-2017, 01:48 PM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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Quote:
Originally Posted by Toobuilder
If we did that, there would be no Rockets!
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Are Rocket fuel systems different than the plans? Didn't Harmon offer plans?
Point being, if you dont know what your doing, (not you), do what the manufacturer of the kit recommends.
__________________
Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
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06-22-2017, 02:04 PM
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Join Date: Sep 2010
Location: Redlands, Ca.
Posts: 1,458
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Quote:
Originally Posted by vic syracuse
Please, please, please don't do this. I was performing a prebuy on an RV-8 today and for the second time I found a fuel valve with a BOTH position. Huge NO-NO! A both position in a low wing aircraft will fool you into thinking it works correctly, especially when both tanks are either full or above the fuel pickup. But let one of the tanks get below a fuel pickup and even if you happen to have a full tank on the other side, it will suck air. Probably at the worst time, like when turning base to final. More accidents are caused by modifications to the fuel systems than any other modification. It was a even very nice Andair valve, too. 😓
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....I actually had a low wing aircraft with a fuel valve set up this way, and I will say it required extra care in use. It had a fuel circulation pump on each tank that could be operated interdependently from one another with switches. The intention was to enable you to select "both" on the valve and turn on one of the fuel pumps to transfer fuel to the other tank for balance purposes. This all sounds like a good idea, but in operation it required to much attention. Way to easy to forget a step and it would bite you. Simplicity is reliability, and the older you get the more important that is as C.R.S. sets in.... 
Thanks, Allan
__________________
Allan Nimmo
AntiSplatAero.com
Innovative Aircraft Safety
Products, Tools & ServicesInfo@AntiSplatAero.com Southern California (KREI)
RV-9A / Edge-540 
(909) 824-1020
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06-22-2017, 02:09 PM
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Join Date: Mar 2014
Location: San Marcos, CA
Posts: 415
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Even Vans says to
Quote:
Originally Posted by JonJay
I got an idea. How about we follow the plans!
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Just as a data point, I was even directed by the mothership to not follow the plans and alter the fuel vent lines in an RV-8 to match a post here on VAF.
The mod was to create a fuel vent in the wing root to avoid running it through the gear towers.
I may be mistaken, but I think that mod originated in a Rocket.
Sometimes good ideas come along, but Vans can't keep changing the plans.
Build well, build thoughtfully, seek guidance, understand what you are doing, fly safe, be safe.
__________________
~Chuck
DG-800S Sailplane
QB RV-8 -- Working on final wiring and the engine
84CX Reserved
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06-22-2017, 02:56 PM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by JonJay
Are Rocket fuel systems different than the plans? Didn't Harmon offer plans?
Point being, if you dont know what your doing, (not you), do what the manufacturer of the kit recommends.
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Don't want to cloud the message of this thread, but in the interest of trivia the first Rocket was built without plans.
And slightly more to the point, the typical Rocket fuel valve has a L - OFF - R actuation, which has you pass through OFF every time you switch tanks. This is a significant faux pas according to FAR 23.
__________________
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
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
Last edited by Toobuilder : 06-22-2017 at 02:59 PM.
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06-22-2017, 03:01 PM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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Silly me . I thought this thread was about fuel selectors.
__________________
Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
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06-22-2017, 03:08 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by 160kt
Any empty tank will allow "sucking air". Doesn't matter if your fuel selector has only a Left and Right position or also includes a Both position.
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True
But it is SOP to select the fullest tank for landing. If a pilot does so, they have at least reduced the likelihood of an un-ported fuel pick-up to near zero.
If they ignore that procedure because they think "hey, I have a both position.... I am already feeding from the fullest tank" and then during landing they either run out of fuel on the lower tank or un-port the pick-up for some reason, the engine will quit.......
__________________
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 ")
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