K

kasTX

Member
Thought I would post a heads-up for those who have not yet installed their fuel senders (float type). A dumb mistake on my part, but pretty easy one to make. I am building an RV-8QB.

I started by modifying my left tank for the flop tube per the plans, which entailed moving the fuel level sender to the back baffle of the second bay. I grabbed one of the fuel senders Vans sent me, bent the wire per the plans they send with them, then drilled a large hole in the rear baffle for the sender and five smaller holes corresponding to the location of the screw holes in the sender. The location of the holes is important, otherwise the sender could be mounted at an angle with respect to the tank. It all turned out great, so I installed the flop tube and other parts and sealed that sucker up. (Anyone see the error yet?)

I then set it aside and got out the right side tank. No modifications are required on this one (other than SB compliance), just mount the access plate, then mount the fuel sender. I put the sender together per the plans and mixed up some ProSeal. (Anyone see the error yet?). I ProSealed/screwed on the access plate, then slathered ProSeal over the sender and stuck it through the hole. Uh oh, I see a problem now - the screw holes in the sender don't line up with the screw holes in the access plate. I didn't expect any problems here since the screw holes in the access plate were already drilled with the nutplates mounted by Vans.

A few minutes of head scratching and I come to the conclusion that Vans accidentally installed a left hand cover plate on the right hand tank. :mad: Darn amateurs! Still, something doesn't seem right... (Anyone see the error yet?) Oops. :eek: A dim light comes on over my head. Sure enough, a closer look at the plans reveals that there are left hand and right hand fuel senders complete with different parts numbers! (F-385C vs F-385B). :eek: There isn't anything explicit in the plans, other than a reference to F-385B/C. And of course, the parts aren't marked with F-385B or C, since they aren't made by Vans. Luckily I can remedy the problem just by ordering another sender. Anyone need a float type sender for the left tank? :rolleyes:

This would not have been a problem if I hadn't made the inverted mods. Or if I had started with the right tank. Or if I had both tanks side-by-side while I was working. Or even if I had come out on top in the 50/50 odds that I would get the two backwards. Or, of course, if I had read the plans and compared part numbers.

Hope this helps someone out there...
 
Good tip.

I almost made the same mistake. It's very easy to do, until you realize there is a left and right sender. Thanks for sharing the story.
 
The Other Mistake....

I thought you were headed towards to the other mistake that many people make - forgetting that last little bend on the sensor arm that keeps the thing from rotating in the nylon holder. It's on the plans...yet, I know four people (including myself) that missed it, and had to make new wires - after getting the wings installed in my case!

We all miss things....

Paul
 
Um, "last little bend"? :eek: Please tell me you are referring to the 1/4" or so bend that goes through where the nylon part pivots...
 
yup

kasTX said:
Um, "last little bend"? :eek: Please tell me you are referring to the 1/4" or so bend that goes through where the nylon part pivots...
Click to expand...

That's the one! ;)
 
Actually...

(Sorry this is long but please bare with me, it could save you some time, money and aggravation.)

If you take a look at the boxes you removed the senders from you will find they are marked. Vans uses Stewart Warner senders, F-385X is Stewart Warner's numbers not Vans. (Note to builders; mark the actual senders with a Sharpy as you remove them from the Stewart Warner boxes!)

According to Stewart Warner's website F-385B is a left hand sender and F-385C is a right hand sender. Since you mentioned you installed the left tank first, you may have put F-385C in it by mistake and the one you have remaining isn't a right hand sender but a left hand sender (F-385B) instead.

What's the difference? Well one difference that you already discovered is the hole pattern. If you drill the holes for each tank correctly and then swap the senders by mistake they won't line up in such a way that the float arms will be 90 degrees to the tank bottoms. One other difference (if I remember correctly), when holding the mounting flange with the sender away from you, one has the float on the left and the other has the float on the right. I can't remember which is which but if you carefully compare the one you haven't installed to the plans, it should match (if I'm correct) as the plans depict the left tank.

One way you can test this theory is either trace out the hole pattern of the installed sender and compare it to the other tank cover or, hold the left tank cover up to the installed sender. If I'm right it will line up perfectly.

Why go through all this trouble? A few things need to be proven before you order a replacement. Did Vans indeed install two left hand covers? Did they somehow get reversed (left on right, right on left)? Are they the correct covers but are installed inside out? Did Vans send you two right hand senders by mistake? Or perhaps, you actually have all of the correct parts and accidently reversed the senders.

Well, if I am right, you will NOT need to order a sender at all, you just need to swap them out and put them in the correct tanks. Pretty easy fix, just remove the right tank sender (F-385C), drill out the nutplates, enlarge the hole where the sender was installed. Then fabricate a larger plate to cover the hole and install the correct, left tank sender (F-385B) in it paying extra attention to the hole pattern to get the sender in the correct orientation. Time consuming I know but pretty straight forward.

Now you could just order another sender or just swap the cover plates from each tank but that still leaves you with the senders in the wrong tanks (left in right, right in left). I would defer to Vans for that answer. I tend to think that if it didn't matter they wouldn't specify or would have used a universal type. If you want the easy way out, please call them first.

Now how do I know so much about these senders? Well, Paul's right, we all miss things. When I built my tanks I put flop tubes in both sides so I needed holes in both baffles. Simple I thought, I grabed both of them and cut holes in the second bay from the end and mounted the senders. Then I found I had mounted them in the second bay but wrong end :( . Oh well, just patched the holes and mounted them in the correct bay. By this time I had reversed the senders, I had the holes correct in the baffles but the senders just wouldn't line up. Well I swapped them back and found they lined up perfectly.

Of course I could be wrong and you are correct with you suspicion. Still, if you find Vans sent two right tank covers, someone out there has two left tank covers. :eek:

Good luck, let us know how it turns out.

Rat
 
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Ratman - That is a good summary of how the whole system works.

Once I found that I couldn't get the sender to line up with the holes already drilled in the right tank cover plate, I studied the whole situation with the vigor I should have studied it with before I started drilling holes. Vans didn't slip me a wrong cover. In fact, they are probably one and the same part, but I can't confirm that since I cut up the left one to make a reinforcement for the back baffle. The mistake was definitely mine.

I can't just pull the sender out of the left tank and use it on the right because I have holes and nutplates already installed that correspond to a right hand sender. I could take it out and make a new baffle reinforcement I guess, but I think it will be easier to just order a new sender for the right tank.

Somewhere out there is a person who just discovered that his 8QB kit did not ship with fuel senders and will have to order some. Well, I have his left hand sender, with the wire already expertly bent, and the sender tested, for a hefty discount. :)

Paul - OK, you had me worried for a minute there. I was at work and couldn't look at the part, so I had to sweat it until I got home.
 
Upside Down...

I've got another twist to this thread... I inadvertantly installed one of the senders upside down (the one in the left tank with flop tube). Once I hooked up the gage, it read in reverse! What to do? What to do? Since the sender is in the aft of the tank and almost impossible to get at without removing the tank...I went to Westberg Instruments and they sold me a gage with reversed ohm reading so that it read correctly! Not to mention they are really nice guys and told me they make this adjustment this all the time. Good gage too.
Just my little 2 cent story....
 
Now that is a great story! Novel solution too. Sure beats rolling it inverted every time you want to check the fuel level. :D
 
Great catch on there being a right and left sender. I only installed the left side and I was worried I may have done the same thing. Luckily the one I still have in the box for the right is a 385C. Great info kas.
 
About to start on my QB wings. About how much proseal do I need for the access and the fuel senders? Also, are people using the cork and rubber gaskets or just prosealing everything?
 
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I dispensed with the cork gaskets and just used proseal. I believe the plans mention this as an option.

It doesn't take much proseal to do the inverted mod on one tank. I have a small can of proseal and still have a bunch left over after doing the inverted mod and complying with the service bulletin. I would imagine you could do it all with one of those syringe size proseal containers if you had everything ready to go in one shot.
 
jlfernan said:
About to start on my QB wings. About how much proseal do I need for the access and the fuel senders? Also, are people using the cork and rubber gaskets or just prosealing everything?
Click to expand...

Jorge,
If you use either NAS1473 fuel tank "sealed" nut plates (available from Sky Geeks or M & M Aerospace Hardware in Miami) OR the self sealing #8 pan head screws available from several vendors (MSC or McMaster-Carr are two) you can forget the ProSeal. The cork and rubber gaskets will work just fine. You can actually re-use the cork gaskets if you are careful.

[url]http://aircraftproducts.wicksaircraft.com/viewitems/aircraft-nuts/anchor-nut-two-lug-floating-nas1473?[/URL]

FYI, I got a great discount on these by buying a bag of 100 from M & M Aerospace. I sold what I didn't need to other RV guys on this list.

Charlie Kuss ;)
 
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little bend

Paul,

I scoured drawing 16A before making the 3" legs and the 90 degree bend in the float wire. After seeing your post, I poured over the plans again with out seeing a reference to any portion of the wire inserting into the pivot point of the sending unit. Today I called Van's builder's assistance about this and several other issues. They said there is nothing on the plans about a bend into the sending unit. When I asked if there was any chance the wire would disengage form the connector block with out a bend or cause a problem if the float rotated, their reply was "never heard of one". I would be very much obliged if you would point out where the bend on the medial end of the wire is indicated on the plan set. It's a small issue but missing something on the plans is anxiety provoking.

drawing16aee8.jpg


Ciao,

Robert Saltsman
1 RV-8 flying
1 RV-8 abuilding
 
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Found It!

Robert,

Well, it had been a while since I had gone through my stack of documents from the build (I don't know about others, but my building documentation - excluding the full-sized drawings - is a stack about 18 inches high!), but sure enough, I remembered what I was looking for - here's a scan of the Van's drawing that shows the bend dimensions, including the little one at the end....without the little bend, the float wire is free to rotate!

I can't say I am surprised by the response that you got from Van's - I found out quickly that the quality of advice depended on who answered the phone....I found that most of the help I needed, I got from folks here and on their builder web sites. I can't imagine how people built airplanes before the Internet!

vanswingfloatwiresrf6.jpg


P.S.: I made my new ones out of extra hinge pin I had laying around....

best,

Paul
 
Paul,

Thank you for your quick reply. I appreciate your effort! Of note, the drawing you posted is not among the plans provided this April when I received my kit. Page 16A shows only the 90 degree bend. The present drawing is for the RV-7 and RV-8 wing. Van's must have redone the drawings.

You are right, the internet provides extreemly valuable building tips. That's why your original post piqued my interest. Not to mention, Van's has quite a profit center resending parts :)

Robert Saltsman
 
Robert,

That drawing wasn't in my plans package either, but was stuffed in the box the fuel senders came in. It is printed on regular 8.5" x 11" paper, not the large size like the rest of the drawings.

Kelly
 
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