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Fuel tank removal

FlyFastJP

FlyFastJP

Well Known Member
I just bought my first airplane...an RV-4. Needs a little TLC but it's in great shape overall.

I'm going to pull the fuel tanks soon to comply with an SB about the pickup tube mounts (can't remember number right now).

Is it a bitch job pulling them, or will it go easy?
 
I'm not sure that you have to remove the tanks...

to perform the SB's, but if you do, it can be a bear. I've done it on my -4.

If the screws are painted you should use a paint cutter like this:

http://www.aircraftspruce.com/catalog/topages/screwpaintcutteran8.php?clickkey=31971

Then use something like a dental pick to scrape out the paint from the screw head so you can get a screwdriver secured in the head. Then push very hard and turn very slow to removed the screws.

I also ran a box cutter blade along the tank skin line to cut the paint at that intersection.

When I was done I removed all the screws and slowly pulled the tank and there was no paint damage.

Hope this helps.
 
Depends..should be easy.

I built my -4 per plans, and could remove mine easily. Take off the root fairings, loosen the feed line and vent line "B" nuts at the inboard tank access plate, disconect the fuel sender wire, remove the bolt attaching the front inboard end of the tank to the fuselage bracket ( You might want to "slot" the fitting if yours hasnt been), remove all the upper and lower screws ( 2 rows at the spar) and the ones around the leading edge rib. Use some protected thin putty knifes to seperate the trailing edge of the tank from the spar flange, as the dimples will somewhat lock it from sliding forward. Of course, its easier if its empty! The RV-4 does not have Z brackets in the middle as do other models.
 
I would think hard about pulling the tanks just to do that particular SB. A "useable fuel" test can determine if the pick ups where rotated out of orientation by an untrained and sloppy builder. You might also be able to inspect through the fuel drain by eye, or with an appropriately sized (small) inspection camera probe. On my 6, you can actually see the pic up screen with the unaided eye right through the drain hole.
This SB was very controversial when it was first issued. It was done by Van's in response to only one incident as I recall. Perhaps there where more, but I don't think so. The fuel system wasn't properly tested or the problem would have been found before that aircraft was ever flown. Dump 18 gallons in, you should get 17.xx out. Simple as that.
So, before going through all of this work, get a few second opinions, inspect and test your system, then decide.
 
The SB is about a nut being able to back off and come loose, thereby leaking fuel. I'm not a builder, so I have no idea how it's put together. Wouldn't it be prudent to at least remove it if need be and look? Obviously do the fix while it's open. I know it's a lot of work, but the A&P that did the pre-buy for me seemed to think it was extremely important. He's done pre-buys on dozens of RV's.

I just want to be safe.
 
FlyFastJP said:
The SB is about a nut being able to back off and come loose, thereby leaking fuel. I'm not a builder, so I have no idea how it's put together. Wouldn't it be prudent to at least remove it if need be and look? Obviously do the fix while it's open. I know it's a lot of work, but the A&P that did the pre-buy for me seemed to think it was extremely important. He's done pre-buys on dozens of RV's.

I just want to be safe.
Click to expand...

I am certainly not trying to talk you out of it. You should understand what the issues is/was however.
The nut did not back off. What happened was the builder didn't know what they where doing and when they tightened the main fuel line, they did not have a wrench on the bulkhead fitting to hold it. The bulkhead fitting rotated and the pick up tube rotated along with it, upwards, lifting it off of the bottom of the tank. This led to a fuel starvation accident.
This can only happen on the left tank. On the right tank, the fuel pick up would rotate down, not up, if you tried to tighten it without holding the bulkhead fitting.
Anyway, some believe every SB should be adhered to, regardless of why it was issued. If you're an A&P with your butt on the line, your going to recommend it be done.
If it where my airplane, I would do a useable fuel test. Check the pickups for proper orientation, and then mark the bulkhead fitting with a sharpie line to the rib so at each inspection interval, when I check that fitting and hose for security, I can see if the bulkhead fitting has moved. I would not remove the tank just for reasons of the SB.
All that said, you need to do what you feel most comfortable with. It is your butt....
 
Johnnie - It appears there are two SB's and one is associated with the fuel pick up coming loose and falling off.
These are two different SB's. The one I am referring to is the Anti Rotation SB that was issued along time ago.
Anyway, if you decide to take the tanks off, you will want to perform both.
 
im in the camp that with the amount of proseal that most people put around the nut, there is a very low probability of it getting loose. but my option is worth exactly what you paid for it.

bob burns
RV-4 N82RB
 
To be honest, I haven't looked into the origins of the SB. And, I just assumed the tanks had to be removed. If I can get a scope, am I able to see the issue from inside the tank? I thought it was outside the tank.
 
Hotel Whiskey

FlyFastJP said:
To be honest, I haven't looked into the origins of the SB. And, I just assumed the tanks had to be removed. If I can get a scope, am I able to see the issue from inside the tank? I thought it was outside the tank.
Click to expand...
Johnny,
Welcome to the best sport-plane you can buy, or in some of our cases, build!
I have my own opinions about calling anything on an Experimental airplane a "Service Bulletin" since that term is used by the FAA for certified airplanes. Especially the "SB" of which you speak.
But I digress...
Unless you have an issue and before you start pulling your tanks, I would rather you contact my two good friends "Cheese" (Chuck) and "Hollywood" (Jeff) at Hotel Whiskey Aviation. They're located at McKinney TX Aero Country and specialize in RV fuel systems. They might even talk you into installing a set of Safe Air one tanks. (I put a set in both my RV's and my HR2. )

They will give you a no BS assessment and give you great feedback on what you need...
V/R
Smokey
http://hotelwhiskeyaviation.com/home/
 
I got the 18 gallon as soon as I read it. Lol.

The plane has been flying just fine. It's got 1051 on the airframe, so it obviously has no problem with a pickup. There is however two rivets on the bottom of the left tank that slowly seep fuel...not leak, as it's been years to show the two stains it has. Could a pickup problem leak in that area?

I'll call the place at Aero Country and get their assessment.
 
FlyFastJP said:
To be honest, I haven't looked into the origins of the SB. And, I just assumed the tanks had to be removed. If I can get a scope, am I able to see the issue from inside the tank? I thought it was outside the tank.
Click to expand...

The pick up tube nut that holds it onto the bulkhead fitting is inside the tank.

One thing to consider, and you will get two schools of thought, is you can do the inspections and any repairs through the wing root, at least you can with a 6. It is tight, but doable. The entire assembly will come out with the inspection cover. Others feel taking off the tank is easier and quicker.
I have only done it to replace a faulty sender on my 6 and it took only a couple of hours. I have no doubt it is easier to do, and much less mess with proseal, off of the wing, it just depends on what factors you are fighting to get the tank off, like painted screws, etc....
Welcome to RV ownership! Fun times. It is good you are looking at these things. You might be shocked to see what people find on airplanes that have been flying for sometimes years and hundreds of hours.
 
Oh...and yes, I got the full set of plans. Well, I assume it's the full set. They are in a big tub. Old **** near brittle drafting papers.
 
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