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RV tank valve failure and fuel starvation...today

N79PT

Active Member
Finally got the wings and tail back on after "Yellow Peril's" trip by boat from Honolulu to New Mexico. The second "first flight" was uneventful as hoped except for the usual sea-level to mountain-level density altitude factors.

After post-flight refueling (and switching tanks) the engine wouldn't start as the boost pump hammered away without fuel. Fiddling with the fuel tank valve (Van's standard issue) from left to right suddenly the right stop no longer worked and the handle rotated almost 360 degrees! I wiggled the handle back and forth trying to find a spot where fuel would flow so I could get back to the hangar. The pump and engine finally did find some fuel to start, but with partial power and running rough at 1000 rpm.

Were there any indications of impending failure? (Luckily this didn't happened in the air 15 minutes ago when I switched tanks.) Maybe yes maybe no. Last year I noticed the valve loosened up a little and would pass the detent (click) on either tank about 5-10 degrees before resting on the stop. The shaft also developed a little slop in it over time--the plane is only 2 years old with about 150 hrs. Once I remember the the valved turned to the detent (but not to the stop) with no fuel flow.

I don't know what the implications are for others with this fuel valve. I'm sure many are using it problem-free. For me it seems logical to invest in the more robust Andair valve just to be safe.

On the ground and happy at E98 (MidValley Airpark).
Greg
 
I don't know what the implications are for others with this fuel valve. I'm sure many are using it problem-free. For me it seems logical to invest in the more robust Andair valve just to be safe.
Glad to hear it happened on the ground, Greg. Do you know what vintage your fuel valve is? From what I understand, Van's changed fuel valves some time ago after there were a number of problems. Curious if this is one of the more recent versions.
 
My belief is that it's the brass-on-nylon valve Van's is selling today. The kit is a quickbuild delivered in 2002.
Greg
 
Scary stuff. Please, pretty please, disassemble the valve or send it to Van's for inspection, and let us know what the problem was.

I assume the valve is a pretty simple piece of hardware -- amazing that you could rotate 360 degrees and not get any fuel. I wonder if there is some sort of obstruction caused by a failure internal to the valve.
 
This has come up in the past and is apparently a common problem. Thus the reason many of use installed Andair fuel valves.

I spoke to one local builder who is flying his second RV and he said the valve from Van's seemed to last about 100 hours between replacements. On his second RV he installed the Andair valve and has had no problems with it. That was all I needed to hear and purchased the Andair valve.

That said, some members of this board have not had problems with the stock valve. Dan, how is your valve holding out, have you replaced it?
 
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That said, some members of this board have not had problems with the stock valve. Dan, how is your valve holding out, have you replace it?

1421 hours, original Van's fuel selector valve. No issues. Haven't touched it.

(edit: ok, I've touched it when I switched tanks; also important to note: 2002 vintage)
 
Question on Detail

My original Van's valve, 2003 or 2004, has clicks, but no stops that I can recall. Is there more than one model, then? Mine has nylon(?) ball inside and a third position - off. 110 hours with no issues.
 
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The BRASS cone in brass body valve came with my kit. I replaced it with the valve supplied in later kits that has nylon cone in BRASS body before I ever had fuel in the tanks or flew the airplane. Have had NO problems and have not done any service to the valve in 2,052 hobbs hours. Tomorrow is 10-years since first flight.

This NTSB report on a fatal RV-4 accident prompted me to change out the valve. Although the valve was not the cause of the accident, I did not like the idea that brass cone in brass body had a very poor feel for the detent when in position.
http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX94FA081&rpt=fa

The Andair valve is a better valve but it is a LOT more money. The nylon cone in brass body has been an adequate valve in my installation installed EXACTLY per the plans.
 
No problems on original valve

but I wouldn't mind the replacing it with the Andair if it was a "drop in" item, however I think I would need to rework the fuel lines which on the 'A' model ain't no picnic :eek:
 
fuel valve

I used the Vans fuel valve for about 750 hours before replacing it. The valve was supplied with my finishing kit in 1999 and is of the plastic cone variety.

The only problem I had was that when changing tanks a very small drop of fuel came up past the spindle. I had previously fixed the problem by putting fuel lube on the spindle but the second time this did not work.

The plastic cone that is used to select the fuel is riveted on to the spindle. This is the only area where I think you may have a problem and that is if the plastic cone is no longer connected to the spindle.

The easiest thing to do to investigate is to unscrew the top of the valve. First making sure you have less than say 1/4 of fuel in each tank. If not fuel will flow out through the top of the valve and you wont be pleased.

If everything seems OK replace the top of the valve but note that there is a keyed position on the washer like device that is used to give a spring feel to the valve when it is in the correct position. You should also note that the valve can be turned through 360 degrees.

Hope this helps

Barry F-PRVM RV6A
 
My -4 was finished in 93. Had the brass/brass valve. It was very hard to turn. So hard to turn I thought the handle might break off. I live close to vans so I compared the Andair vs the new brass/plastic stock at the counter.

Cash drain alert: Once you hold an Andair in your hand, try the feel of the selector L / R / OFF, think for 5 seconds about how critical the fuel selector is for your butt, the next plastic thing you touch is your credit card as you take it out of your wallet.:eek:
 
Accident Data

The BRASS cone in brass body valve came with my kit. I replaced it with the valve supplied in later kits that has nylon cone in BRASS body before I ever had fuel in the tanks or flew the airplane. Have had NO problems and have not done any service to the valve in 2,052 hobbs hours. Tomorrow is 10-years since first flight.

This NTSB report on a fatal RV-4 accident prompted me to change out the valve. Although the valve was not the cause of the accident, I did not like the idea that brass cone in brass body had a very poor feel for the detent when in position.
http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX94FA081&rpt=fa

The Andair valve is a better valve but it is a LOT more money. The nylon cone in brass body has been an adequate valve in my installation installed EXACTLY per the plans.

I am not disagreeing with the mechanics of the valve, and one's decision to replace one for another. But with regards to the accident in question, from the description and the post-accident investigation, there appears to me more going on here that a presumed "broken valve."
In my opinion, even an Andair equipped aircraft would have similar results if the valve was incorrectly installed. It seems that sans one fitting, every connection and even the physical installation was questionably torqued.
Another key was the fact the aircraft had only 40 hours until the accident, which leads me to believe that the builder/pilot was able to get away with connections that were "finger torqued" for a limited time.

A sobering lesson for all of us to remember to recheck those critical areas where we are just "trial" fitting, and not to rely on merely a mental note: "I'll have to remember to go back and re-torque that fitting."

Something else here that I learned way back in the early days of my training,,, not to touch the fuel valve after engine start. Make sure the valve operates and "feels" correctly and set it to the fullest tank during the preflight. That way, if there is an issue, you would presumable have a little more altitude/time at your disposal as the aircraft would more than likely run out of fuel well before take-off if there was an existing issue with the valve.
 
Ditto what everyone said about the Andair valve. You need to lift a spring loaded plunger to turn off the fuel, and there's no doubt about what position it's in. Can't say that about the stock valve. The Andair valve looks like a piece of art next to the stock valve. My choice was to spend more money on that (a lot more), and less on avionics. Not as sexy, but I'll feel better about it. You pay your money, and you take your choice.

Clear skies,
 
seems like a no-brainer to me

I'm not yet at this stage, but after reading this post, it seems like a no-brainer to me to use the Andair valve. Just how much extra is this one over the stock Vans valve?
 
Yes, this unfortunate accident has several lessons to be learned.

Use torque seal (see Aircraft Spruce catalog) to mark finished and torqued fasteners and fittings. At final inspection, all should show the seal mark. Use experts (experienced builders and/or EAA Tech Counselors) for final inspections. All critical stuff must be inspected by knowledgeable folks beside the builder.

Fuel, oil, ignition and other flight critical systems need careful inspections and watches for unusual or incorrect operation. All anomalies must be debugged and fixed before flight. Be on high alert during all phase I operations or after any maintenance/modifications.

All fuel selector operations must be during non critical ground or flight phases. Don't change tanks in any situation in which adequate time and/or altitude is an issue. Don't run tanks totally dry in case a newly selected tank has problems.

And I'm sure there are more...
 
I recall paying about $175 from Andair at SnF

The other costs are replumbing the fuel lines (harder to do that it sounds). It also took me better part of a weekend to get it done.

Lastly I had to get some new AN fittings (from JEGS speed shop) to complete the job.

Bruce
Sold my RV-8 (after flying it almost 500 hours)
Hope to be flying an RV-10 soon.
 
Looking at the Andair website, it looks like that valve would be a whole lot easier to plumb than the Van's "cross-over" design. Man, I spent a lot of time trying to get those bends right, and it still didn't come out perfect. Next airplane I'll certainly look into the Andair.
 
Cash drain alert: Once you hold an Andair in your hand, try the feel of the selector L / R / OFF, think for 5 seconds about how critical the fuel selector is for your butt, the next plastic thing you touch is your credit card as you take it out of your wallet.:eek:

You took the words right out of my mouth. My friend's -6 has the old valve, I have a new Andair. It's like night and day. I still have the newer model Van's valve sitting in a parts bag on a long forgotten shelf. It's not bad, but - yes, the Andair is a work of art and worth every penny, IMHO. It's like insurance - I bought peace of mind. No doubt it is a spendy part, but the workmanship and design are second to none.
 
I have seen and felt the Andair and it does look and feel mighty nice. But while we're all here bashing the stock part, has anybody actually opened up the Andair so that they can tell me exactly what makes it so much safer than the stocker? I realize my brass valve doesn't have much in the way of detents, but neither do those on many certified craft. Are we really concerned about accidently shutting off fuel while swtiching tanks? Really??
 
Andair sighting

I don't know if any of you realize this or not but the Andiar valve us used in the Symphony 160.

big_73382371.jpg


I'm not sure you would ever see that boiler valve included in our kits in a certified airplane.
 
What valve and part number has been the one most used to replace the Van valve? I am building an 8a and right at installing the valve in the fuselage.
 
Fuel valves have troubled me for a long time. I used to fly a V-35 Bonanza with the fuel selector under my left knee. It was hard to tell if it was in the proper position and impossible to visually check. It had about the same feel as the stock Vans brass valve. Once, about 10 minutes after switching tanks at altitude, the engine started loosing power. I switched tanks and put the boost pump on and the engine picked right up again. When I switched to the different tank I realized I had not gotten the valve in the correct position and had starved the engine.

I bought an RV-8 two weeks ago, and this fall will convert it to Andair. I don't want to worry about the fuel valve sticking or being out of place. You might not even know it until you added full power for a go around! If you want further proof of caution with fuel valves, read the accident report on John Denver's Long-EZ fatal crash. There were many contributory factors but a sticking fuel valve was one.

The newer Vans valve may be fine too.
 
Fuel Valve

The fuel valve Vans sells is quite a simple and robust piece of hardware and is probably as reliable as the Andair one. I took my old one apart last night before replying early on in this thread. There is a mechanical click on each of the four positions so one can feel when it is positioned correctly. Also in the RV6 it is easy to see which position has been selected. Sure the Andair one which is used in certified aircraft such as the Cirrus looks a nice piece of engineering as it is anodized and has each fuel position marked on the outside. Whether the Andair is more reliable in other words less likely to break I am not sure however it costs about 7 times more than the Vans standard fuel valve.

The only issue I had with the Vans valve was a very slight leak when I changed tanks on the start of a decent before landing. As I was at say 160 Kts IAS the airspeed was pressurizing the fuel tanks a maximum. As the fuel leaver was moved from one tank to the other a very slight hardly visible spot of fuel leaked out of where the spindle enters the valve. This ever so small drop of fuel could be smelt in the cabin and often caused my wife to suggest something was amiss. Not wanting to change my seat covers and trousers for the inflammable kind due to the possible risk of fire I replaced the fuel valve!!:)

Barry F-PRVM RV6A
 
The fuel valve Vans sells is quite a simple and robust piece of hardware and is probably as reliable as the Andair one.

I honestly doubt that is true. To date I have never heard of ONE case of a failure, or fuel leak, or other malfunction of an Andair unit.....but numerous reports of the Vans unit malfunctioning are a matter of record.

When I got my Vans selector with the kit I just tossed it in the back of a drawer and ordered an Andair unit immediately. There's absolutely NO comparison in terms of quality between the units. The Vans unit looks like a tap out of a 19th century bath house.

There's just some items on a plane that are not worth penny pinching on...and a fuel selector is one of them.
 
My Van's fuel valve has been working just fine for over 3.5 years of flying. Sure, the Andair is a very nice valve and I might use it as a replacement, if I ever need to.

Roberta
 
I went through the entire fuel system today with the exception of pulling the inboard tank inspection covers. Everything operates as it should, with and without the engine running. The fuel tank valve was dissembled and every component looked good with everything in it's proper place and doing what it's supposed to do. The problem could not be duplicated in any way.

The only thing I can attribute the the string of symptoms I observed and the conclusion I made is "operator error." Perhaps this was a case of serious vapor lock that I didn't recognize? I am certainly familiar with the sea-level characteristics of this engine (I've got the Ellison TBI) but not at a density altitude of about 8000 ft.

I apologize for jumping the gun without all the facts. I had concerns that something seriously bad could happen to someone if I didn't alert the group right away.

Greg
 
I'm not sure you would ever see that boiler valve included in our kits in a certified airplane.[/QUOTE]

Actually the Imperial Eastman brass on brass valve was used in most all the old 65 hp two place aircraft of the 1940's, through the 1970's including Luscombe, Ercoupe (I think) and the 170/172 Cessna's, probably all the Cessna 100 series.

Cessna just installed it below the floor with the handle removed, added an extension shaft to the remaining stub shaft and a new Cessna designed handle in the cockpit. The valve body including the detent is the same. My 1949 Cessna 170A has 4000 hours on one with only repacking with fresh fuel lub. when it feels stiff. My RV6 has 200 hours on one and it works fine with no trouble determining if the handle is correctly positioned. I have 1600 hours in aircraft with the Imperial Eastman valve either plainly displayed as Van's recommends or disguised a'la Cessna.

The Andair is a nice valve and one should buy it if it makes you feel better but the stock valve is a proven, functional, economical valve that has stood the test of time. Actually, the Imperial valve has been very adequate except for recently when suddenly all these problems started to arise which I feel are largely a perception of a problem rather than a real deficiency. Just my 2 Cents.

Dick DeCramer
Northfield, Mn
N500DD RV6
RV8 fuel Tanks
 
My Stinson had the same--or very similar-- brass/brass valve. It was still working just fine after 59 years when I sold the plane.

But, remember as in most mechanical devices, there is periodic maintenance needed. Disassembly, cleaning and re lubricating with the correct fuel proof lube, will keep these units going for a long time.

If it is leaking, or hard to turn, that is a red flag that you need to do some basic maintenance work.
 
Paul,
The detents always worked. I mistakenly thought the valve malfunctioned when it went through the "stop". I forgot there is not "stop", and never was, and never should be for this four position valve.

I have to confess there was a little pressure landing on the 37' runway at Mid Valley vs the 150' wide one at Honolulu coupled with the high density altitude handling of the plane--and don't forget the excitement of hoping all the wing bolts were tight. So I may have not followed my normal heat-soaked engine start procedures after the refuel, thus the potential for vapor lock.

Thanks for all the comments and concerns.
Greg
 
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