What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Why sump your tanks?

Spindrift said:
Friday after 3 weeks of steady rainfall...
8158288713_6f9f908706.jpg
Click to expand...

That is impressive (but not in a good way)
 
Holy cow!! Always check; never any contamination. I'll remember this pic whenever I'm feeling lazy.
 
How did that AV gas get in your rain gauge? ......................



I never trust the caps. Parking outside, I cover them with a small static plastic cover like the press in place sun screens.
__________________
 
I picked up a load of water from the tank at the FBO in Hastings, Ne on the return from Osh 11. Thought I got it all before takeoff, but my engine swallowed a big slug of it over the wastelands of Colorado several hours later. It took several tanks of gas and a complete draining of the tanks to finally be completely rid of it. Like the OP, I've never seen that before.
 
Ron Lee said:
Will a perfectly maintained fuel cap allow water in?
Consider taping (or similar) over the fuel caps.
Click to expand...

Caps in good condition should do a pretty darn good job of keeping the water out. Mine stayed perfectly water tight during all the rains at Oshkosh 2012 without any tape over them. Taping over them while parked for an extended stay (e.g. camping, etc) sounds like a good idea.

I still religiously sump my tanks anytime there's been the possibility of water getting in them, or after refueling at an unfamiliar airport... especially since I once got about a cup full of brown rusty water in my Cherokee after fueling up at an airport near San Antonio about 11 years ago.
 
Sump before every flight (over 500 times now) and never a drop. Due to never finding any water, I have wondered if they are actually draining the very bottom of the tank. Even thought of testing by putting in some water and seeing if it came out of the sump. (actually would never really do that).
 
...and how MUCH to sump?

...a great pic showing that if you only sump an ounce or 2, you can get a nice, clear, clean sample...........of NOTHING but WATER!
I'm a bit colour challenged, so I don't see the pale blue fuel tint we get here unless it's in really good light, so I hold the sample tube against the fuselage to see the colour.
I also smell the sample, but that only works for the first drain of the day...then it all has a hint of avgas aroma.

I rarely get a spec of water, even with old gaskets and sitting outside year-round, ( snow, ice, rain, rinse, repeat)
 
I wonder how long after a a fill up of fuel that one needs to wait for the contents to settle and any or all contaminates rest at the lowest part of the fuel tank/bladder.

I recall but cannot find the back up documents that one needs to wait :30 minutes. I'm sure that this would vary from tank to tank based on size.
 
Just as a point of ref... We filled up at that Hastings FBO, then spent 45 minutes on the ground eating lunch. My first sample was almost completely full of water, and it took 5 or 6 cups to get a clean sample. The other ship (an RV6) never picked up a drop.
 
Check the stem o-ring on the cap. Also, there should be a moderate amount of pressure with your thumb to cam-over the fuel cap tab.
 
To be honest I didn't sump since Phase One. I don't even have sampler anymore. Looking at that water I probably should. I do fair amount of flying and burn some gallonage of premium car gas if available. Wet vfr happens once in a while. Every time I am in the hangar I drain a bit of fuel to clean something and that's all. Never found any water in gascolator during routine inspections. Maybe alcohol absorbs it?:D
 
water

wow
They have these new gas filter funnel that lets the gas thru but not water.
At your auto store. Not sure how to make them work with a gas pump yet.
Bill J

Paid this year.
 
A bit more to the story

The AvGas you see in the picture is actually from the right tank which had only a tiny bubble of water in it. That tank has a new cap that I bought as a backup before flying to Oshkosh in 2011 and installed when the tab broke on the cap. Rather than pouring back in, I waited to see what I would find in the left tank. I expected some water because I knew that the cap was leaking a bit when the tanks were full in hot weather, and I had plans to get a new cap for that side as well. I did not expect a full cup of water. To Toobuilders point, the sample would have been all water if not for the AvGas from the other tank. After pouring this out, I got another inch or so more of water, then shook the wing, waited ten minutes, sumped until it was totally blue, then took off on the other tank and switched over at altitude just in case.
 
Last edited:
Fuel contamination

Something to consider. The very low rate of flow thru the quick drain may not be enough to evacuate/flush the grit and debris that over time collects in the tank. I once replaced a leaking quick drain on a mooney using the "wet" method. That is go out on the ramp safe distance away from everything, put clean bucket under wing, ground the plane and bucket, quickly remove and replace the quickdrain. Was about to pour the collected 2-3 qts back in the tank but found a lot more junk and water than expected in the bucket. This plane i had flown a couple hundred hrs over several yrs and never saw a speck of anything come out of the drains. Now at annual time I remove the quickdrains and flow about a gallon of fuel. Usually collect something.

Don B
Rebuild in Prog
RV9
 
Not trying to be Mr perfect or Mr Paranoid, but why wouldn't you sump before each flight??? maybe I'm paranoid but I sump before every flight. To each his own I guess. It seems like 30 seconds worth of sump'ing is worth it.
 
kinger said:
I wonder how long after a a fill up of fuel that one needs to wait for the contents to settle and any or all contaminates rest at the lowest part of the fuel tank/bladder.

I recall but cannot find the back up documents that one needs to wait :30 minutes. I'm sure that this would vary from tank to tank based on size.
Click to expand...

I use mogas and check it every time I go to the gas station to fill my portable fuel tank. Most water settling in gasoline will occur in well under a minute. If I found water in my wing tank, I would sump until its gone, then shake the tank and wait a couple minutes and check again. 30 minutes is way overkill, IMO.

Greg
 
Smart Risk Mgmt

As a relatively new/old pilot I've tried to look at all aspects of flying from a sensible risk mgmt perspective. Things that are easy to do that have a high probability of paying off big (even if the chances are low), but especially if they are high. I usually wear Nomex because it's cheap and easy to put on even though the chances of an inflight fire (if plane is properly maintained - by me) are really slim. Conversely, as I understand it, fuel starvation is one of the most common causes of incidents, and it's pretty easy to eliminate two major contributors to it - bad fuel or not enough. I sump tanks before every flight and pour it back in the tank - if it's clean. That makes me look at the sumped fuel AND verify visually that there's enough blue stuff in each tank. I could probably do more, like what DR has done with the helmet, and I probably will as time goes on. It's a very individual choice but this one just seems like a no-brainer.

My $0.02.
 
kinger said:
I recall but cannot find the back up documents that one needs to wait :30 minutes. I'm sure that this would vary from tank to tank based on size.
Click to expand...

Only place I've seen this in writing is in the UH-60 operator's manual. It's been a while, and I don't have it in front of me, but I believe it was 1-hour per foot of tank depth. Have to believe it would be similar in all aircraft as the effects of gravity on the water in the fuel is the same while at rest.
 
You must log in or register to reply here.
Back
Top