Oshkosh 2011, Fuel Samples

[Bill James]

Subject: Fuel samples
Everyone knows what it looks like when they get a little water in the fuel, right? Nothing to it. For almost 15 years there has never been a significant amount of water in a fuel sample from my plane. Lots of folks say the same thing about their Ezes and often attribute the clean fuel samples to less or no fuel condensation in our fiberglass fuel tanks. Whatever. Lulled by routine and complacency, this year at Oshkosh I was treated to the refresher course in indications and paying attention to the fuel sample. This beneficial event will be a front-burner awareness for some time.

Bottom line, during the week water got in the fuel system during several periods of significant rain. While I have never had this happen before, others have.
Next bottom line, the fuel system design and airplane functioned well. It started normally. When I raised the nose and climbed in it died. A good thing. Very good.

A description of the fuel system on my plane includes the statement that one must be extremely careful if even thinking of messing with a fuel system design, and that the rear seat sump tank in mine is the best safety item on the plane. No change here. I simply should have been more suspicious because of the rain, and paid more attention during preflight. As with the many valuable truths in life and Sunday school classes and sermons I have experienced, I am not pointing at anyone but myself.

I feel like you guys that get a little water during preflight all the time are probably better off. Once I paid adequate attention, I ended up draining several ounces of water from the plane’s low point. Filling and emptying several beakers of water from the drain valve was good practice in determining when you are actually getting just fuel. You hear that in an emergency all pilots spend the three second delay saying this can’t be happening to me. That thought can also be a strong factor when squinting at and smelling the fuel sample. In a standard training environment, like the flight instructor demonstrating it to the student during a training flight, the color and line between the water and fuel is unmistakable.

We have all seen the various techniques and cups.  Almost any day you can observe a pilot preflighting and running a little fuel on the ground and analyzing it by looking at the pool for several seconds and then nodding. I suppose the desired condition here is a pool of fuel with a little glob of water in it. (Sorry, I am not judging here or dealing with proper handling of the fuel sample afterward, but rather just the pilot preflight stuff    )

The take-away? Just for fun – do some practice fuel samples. Play with your fuel tester device, whatever it is. But besides using your normal method, get another pilot to play Are You Smarter Than a 5th Grader for you with a few set-up test samples, for example including pure fuel in one and another sample with water with a little fuel stirred in immediately before he hands it to you to analyze it. A surprise ounce of Jet-A in a sample cup would be instructive.
Is your current technique the best for your plane?  

To Terry Schubert-  Sorry you happened to walk by at the wrong time. Thank you for your help in pumping the water out of the carb. I say, at least we got to spend some quality time together  
You asked what I would be doing to remedy or prevent this again. First, as you mentioned, I believe the fuel caps are where the water entered. So they will get some attention. Second, I have and will pay more attention during prefight.
All in all, another great trip, still trying to catch up with you guys  

[LongEZDaveA]

Great post Bill.

In my pre-Long EZ life, I was more accustomed to finding water in the tanks upon testing.  I've become accustomed to it being a rare finding in the Long EZ.

I replaced the o-rings in my fuel caps a couple of months ago.  Even though the o-rings were only a few years old, they were weather cracked and in need of replacement.

After the first day of rain last week at OSH, I checked my sumps and found water in the left tank (maybe a quarter teaspoon) and none in the right tank.  I was disappointed that the newly rebuilt caps had allowed rain to penetrate.  I then taped up my left fuel cap.  After the rain the next day, no water was found in the sumps of either tank.

I guess my main point is backing up what you are saying.  Even though there is less chance at finding water in the composite tanks, it does happen and we need to be wary of it.

[cloudman]

Bills post about water in the forward portion of the tank when parked reminded me of something similar yet different.

I had been flying my Varieze at altitude and nosed over into a pretty steep decent angle. I was still quite a few miles from my
destination airport and knew I was getting low on gas in the main tanks. As soon as I nosed over the engine started to quit,
so I switched to my header tank and continued to the airport. I guess there could still have been several gallons left in each
strake. At the time I did not reason out the problem.
I suppose this situation may have been brought up before about the Varieze with a gravity feed system, but thought it was
worth mentioning.
Wayne Johnson.......Varieze 725EZ

[easyrider]

I have had my Long cut out while in the pattern.
I had about 2 gall in the left tank and I was in a right hand pattern and the left tank was selected.
I was in an un co-ordinated turn so the fuel was at the outside of the tank and unported.
A quick change to the right tank and the engine fired right up.
Lesson learnt.
Always select the inboard tank in the pattern if fuel is low.
Do co-ordinated turns.
Unfortunatley my wife was in the back seat, maybe that's why she doesn't fly with me anymore.
Easyrider

[av-mech]

Easyrider,

I did the same thing when I started flying my Vari.  I was in the first three hours and had been flying around the airport, climbing, cruising  and whatever else just to feel the airplane out.  I had just come down out of 10K and was in a left downwind for 13 when the engine began to sputter.  I quickly changed to the head and she fired right back to life.  I made a beeline for the runway.  I had underestimated my fuel burn during those first three hours.  When I made it back to the hangar I checked both mains and the left was empty and the right had about a gallon.  Stupid mistake but I learned from it.  Fortunatly I stayed near the airport for about the first six hours until I had a better feel for the airplane and it's fuel burn.

[go ez]

Vari Eze Handbook is very specific about using the fuselage tank on long descents or in the pattern when low on fuel due to the fuel moving forward and uncovering the fuel feed pipe from the main tanks. Long Ez is less affected (but not indefinately immune) as it has fuel sumps that hold back a small amount of fuel. It is immaterial whether the system is gravity or pumped.

[av-mech]

go ez,

You are 100% correct and I had read that several times before flying.  For me it was a clear cut exmple of pilot error, no doubt about it.  Despite my effort to be completly prepared and schooled, I still made a mistake, I was fortunate that I knew instantly what the problem was and switched tanks immediatly.  This does provide proof that when flying a new airplane, there are many things that can creep up on you.

[Super-EZE]

Bill,

What is the configuration of your rear seat sump tank? Do you also have the rear header tank?

Thanks!

[cloudman]

I think it is great that we are willing to share our various situations or incidents that could have gotten us into more trouble.
This is with the idea that sharing will hopefully keep someone else from doing the same thing and having a more severe
result. My situation involved getting with ATC at the time and not paying enought attention to flying the plane. I don't suppose
that I could use the new plane excuse, since at the time I had been flying my Varieze for about twenty seven years.
I had not thought about that the LongEZ also has the same problem even with a fuel pump......just was not thinking clearly.
I really do like the insurance factor with the header tank on the Varieze.
Wayne Johnson      Varieze 725EZ

[Bill James]

Super-EZE
How does my fuel system work?
Thoughts on this fuel sample mainly had to do with becoming more familiar with how my plane’s fuel system works, and that a periodic review can be beneficial. It sounds like the systems in our planes are pretty good at reminding us to pay attention. As with all things, the difference is how much fudge room we have.

As to periodically reviewing a system, during a wonderful morning full of airplane people at Oshkosh, I had an interesting moment at the plane. I was describing the details of the plane with a particularly adept new friend. Well into the chase, he pointed at a control rod on the right console and asked what it was. The usual rapid fire answer did not materialize. I initially saw an image of the exit vent under the aft arm rest console that is opened and closed by a similar rod. But that one is on the other side. I frowned at the rod for a moment and couldn’t immediately “see” what it was connected to back under the right arm rest or hell hole; and then easily said “I don’t remember…but I’ll think of it in a minute,”  and continued answering his previous question.

A moment later we were kneeling back under the engine and I saw the 2” heater tube sticking out of the firewall, built in while constructing the plane, but never used, or thought of, for fifteen years. “That’s it,” I pointed and said to him, “the heater control valve. That’s what that rod does.” And again I “saw” the internal control rod actuating the heater valve. Whew. Less than a minute to remember. Not that bad. But in an emergency, a similar delay could be… more eventful.

Its possible that the more subtle details of a system can kinda disappear if we dont focus on them periodically. Since being prodded awake here I have physically traced the elements of the fuel system and each detail is now readily "viewable" mentally at a moments notice. For awhile.

I think a good review of the fuel system starts with a detailed perusal of the plans,  and a good investigation of the whats and whys of the system. For example, exactly what do the fuel sumps on the LongEZ do. -What if the LongEZ that you bought doesn’t have them? -What is the backup? What do the plans and CPs say about the design, and what does the system do during start versus cruise.  What kind of pilot stuff we are supposed to do while descending for a prolonged time? Each of these situations is definitely a factor and we should know exactly what is happening.  

My VariEze has no header tank. Instead there is a five gallon sump tank below the passenger thigh support. There are a couple of things I could have done last week to make the water less of an issue. Whatever, we should each be able to “see” the details of our plane's fuel system, and other systems, exercising diligence in operating our airplanes.   …Do some of that pilot stuff  

[dorr]

 There are about 10 types of caps - sorry it doesn't apply to all of them.   I had a thermos type fuel cap on a Long EZ.  I often had water in the tank too - not from the cap seal, or the primary cap seal, but because I didn't know there was a second seal under the nut that helps adjust the tension of the cap lever.  I mistakenly put a washer under the nut on the central bolt of the fuel cap - the washer had edge hole so I could rig a chain to keep the cap from going through the prop.  It later dawned on me that the finger/thumb hole in the cap actually collects water and funnels it to the center bolt and if you destroy that center bolt's seal, it is worse than having a bad seal seal around the cap.  I solved the problem by simply drilling a small hole through the bolt shaft beyond the center seal of the fuel cap bolt, below the tension nut. Having a fuel cap secured with a chain is vital on Varieze, probably vital on Long EZ... rather than drill through the tank ring for the other end of the chain, I found a simple pcv pipe elbow can tether the other end - if the chain is attached to the elbow's bend.  Had the cap dancing around on my strake descending into Guadalajara on that chain - full test of theory.

Beagle

[BruceHughes]

I have "ACS flush fuel caps".   I guess a lot of people use them.  They have a safety chain to prevent the loss of a cap.   HOWEVER the connector that holds the safety chain to the cap is a type of steel which corrodes badly.   Check yours; it may not be good enough.

Bruce Hughes