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sending unit help/question
http://t18.net/thorpforum/viewtopic.php?f=19&t=8072		 Page 1 of 3
Author:  Lou [ Tue Apr 11, 2017 11:21 am ]
Post subject:  sending unit help/question
Problem: So, it's a week/half before the Sedona flyin. aaaannnnd my fuel sending unit decides to stop doing its thing.

situation: I've got probably a months worth of work in the shop (for most humans) that absolutely must be done before I go. Between me and Sedona is a shit ton of nothing but rocks and max range legs.

I've read enough on this forum that the fix is to hack my way through the boot cowl, replace the sending unit and put in an inspection plate. I can probably find the time to put a sending unit in.

Question: aside from the humility of the whole thing what do the engineer types think might be the structural ramifications of ducktaping over the hole for the trip and fixing the inspection cover after?
Author:  Rich Brazell [ Tue Apr 11, 2017 3:29 pm ]
Post subject:  Re: sending unit help/question
Mr. Lou : Finding where to cut the hole and replace the sending unit is 90% of the job . If I remember right after I cut the hole it took me couple of hours to make the peek-a-boo plate . However , in a pinch it may ( I said may be possible) to cover the small hole with a couple of pieces of "Gorilla tape ?" It may require an engineer to qualify this "repair" , but I know for a fact that the airlines and the military use "tape" for temporary repairs until the next repair station is made . Not a very comforting feeling for passengers when they look out the window and see "duct tape" on the engine cowling !

RB O0
Author:  dan [ Tue Apr 11, 2017 8:09 pm ]
Post subject:  Re: sending unit help/question
How large is that hole going to be Lou? I don't have an inspection plate on mine either, agreed it is a pain. (Can't say Rich didn't warn me either) Is your boot cowl .025 or .032 ? can you post a picture of yours Rich? Dan
Author:  Rich Brazell [ Tue Apr 11, 2017 8:47 pm ]
Post subject:  Re: sending unit help/question
I am going to the airport tomorrow and I'll measure and try and take a pic . If I remember right (and I remember EVERYTHING!) the hole has to go in between (2) stringers/stiffeners on the cowl . Maybe 3 inch in dia. ? In the future please listen to the all knowing and powerful OZ .

RB O0
Author:  Fraser MacPhee [ Tue Apr 11, 2017 8:57 pm ]
Post subject:  Re: sending unit help/question
Shorten your legs to 2.5 hours - that's the maximum range of my bladder anyway. Your T-18 covers a lot of RE in 2.5 hours - Even at 9 GPH, you're still well within VFR reserves. I trust my bladder more than my fuel sender/gauge. And if you can't make it 2.5, have Renee hold the Gatorade bottle.. See ya soon brutha!!
Author:  dan [ Tue Apr 11, 2017 9:41 pm ]
Post subject:  Re: sending unit help/question
Thanks Rich...! Ah,er OZ!!!! Frase has the most sensible remedy, I flew for I don't know I think about 4-5 yrs with no fuel Guage cause I didn't want to remove the tank, but I did get er done yr before last I believe, moved my tank vent in the process. Just plan a little different on your Flight Lou, now then, you don't have to do anything until you get home!!!! Easy! See Ya ther Lou. Dan
Author:  Jeff J [ Wed Apr 12, 2017 8:36 am ]
Post subject:  Re: sending unit help/question
It's a little late for this instance but the builder of mine made it possible for the fuel tank to be drained removed in under 2 hours. Would be less but the canopy gives me trouble and it shouldn't have to come off to work on the sender anyway. Removing the panel takes about 30 minutes of the 2 hours and will be quite a bit less when I finish swapping the analog gauges for digital so they all connect through one connector instead of individually.
Author:  Lou [ Wed Apr 12, 2017 12:40 pm ]
Post subject:  Re: sending unit help/question
Thanks for all the feed back.
Oz, i would appreciate the hole size measurement/pics if it comes to that. don't like cutting into the thing a day or two before I head out but...

My second or third flight after getting my PPI check ride I took a fried for a ride. topped off the C150 and hammer down. 30 min later we were over the mountains and battling 30 mile per hr head winds. I knew we couldn't make the round trip with out a fuel stop and I didn't want to land it in that wind so I called it, and we turned for home. About then my buddy noticed both fuel gauges were resting on empty. i told him what EVERYONE told me "not to worry, fly by the watch and have it on the ground in three hours". But it just laid there, not bouncing around like usual. I looked at the gauge, looked at him, looked at the mountains in front of us, looked at my watch and repeated that several times. I then decided to land at the nearest and stick the tank. I really did not want to land in 30 mph winds but I did.

After 45 minuets of flight and leaving with overflowing tanks there was one gallon of usable fuel remaining. Had I ignored the gauge I would have ran out of fuel over rocks and pine trees and dealt with landing in 30 mph wind in the mountains with a grand total 80 hrs under my belt.
I think we know how that would have turned out. I'm not going to tell others how to do there thing but I can't carry my girl without knowing how much gas I have, the entire flight would be nothing but worry. I'll get something sorted.
Author:  Jeff J [ Wed Apr 12, 2017 1:38 pm ]
Post subject:  Re: sending unit help/question
I is good you followed your gut and did the safe thing but where did the fuel go??? Two and a half hours or more doesn't just disappear. Someone leave a cap loose?
Author:  dickwolff [ Wed Apr 12, 2017 1:43 pm ]
Post subject:  Re: sending unit help/question
Running out of gas can ruin your whole day. Even over flat country.

Trust me. I know. ... all too well.

D
Author:  ljkrume [ Wed Apr 12, 2017 2:01 pm ]
Post subject:  Re: sending unit help/question
Lou,

Here's a couple of photos you can use to locate your sending unit (see hole on left side). I believe this is per plans (about midway fore/aft along top?), but it's been a while. The extra tube is for top filling from wing tanks. Logically, it's between stiffeners as you say, and almost halfway on longitude between firewall and the dash frame. Scale the photo and you'll be close enough for a starting hole. Don't drill too deep1 Ha, Ha. When you're done hacking on it, try a dentist's mirror to look around the top of the tank for chips, etc.

If you want to temporarily cover it with a plate, maybe use a few pop rivets, then tape over it against rain. Aluminum types are easy to drill out when the time comes, if you first pop out the mandrel. Tom Hunter showed me once how oval holes allow you to insert oval doublers underneath the skin from outside.

Hope this helps,
Les

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Author:  Hagle347 [ Wed Apr 12, 2017 3:21 pm ]
Post subject:  Re: sending unit help/question
What Fraser said- well, then I read your story. You gotta do what's comfortable.
Author:  Lou [ Wed Apr 12, 2017 5:12 pm ]
Post subject:  Re: sending unit help/question
Jeff J wrote:
I is good you followed your gut and did the safe thing but where did the fuel go??? Two and a half hours or more doesn't just disappear. Someone leave a cap loose?


I would have figured that out when I stopped for gas. So I filled my tanks and hauled ass for home ( ya that was stupid). I didn't see any sign of leaks, at the time so I figured I screwed something up.
flew 30 min back to the home field and the tanks were nearly dry again. nobody was around so I left a note on the yoke and another note in the log book with several friendly suggestions as to what they could do with their 150. I never went back to the school. I was well on my way to having my Corbin baby ace flying.
But, the next time I went to the airport the 150 was torn apart in the shop.
Author:  Jeff J [ Thu Apr 13, 2017 7:54 am ]
Post subject:  Re: sending unit help/question
The only reason loose fuel cap jumped into my mind is because I have "been there, done that". I lost 10-15 gallons in the time it took to fly a tight tear drop back to the runway but I had left the cap completely off (couldn't reach it from where I had to pull the hose then allowed myself to be distracted before I finished). I am glad that wasn't what happened to you.

I am going to miss the blue dye when 100LL goes away. It makes for a very good leak indicator and locator.
Author:  Lou [ Thu Apr 13, 2017 10:30 am ]
Post subject:  Re: sending unit help/question
Jeff J wrote:
The only reason loose fuel cap jumped into my mind is because I have "been there, done that". I lost 10-15 gallons in the time it took to fly a tight tear drop back to the runway but I had left the cap completely off (couldn't reach it from where I had to pull the hose then allowed myself to be distracted before I finished). I am glad that wasn't what happened to you.

:)


I am going to miss the blue dye when 100LL goes away. It makes for a very good leak indicator and locator.


I think we are all going to miss the lead.


i'm probably going to go with the temporary cover plate. thanks all for helping me sort it out
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