Wing fuel gauge fell off (?)

[dkkim73]

Hi All, 

Pre-flighting this morning, I noticed my left wing fuel gauge was missing. I saw a cloud-like white mass which looked like chewing gum but seems to be a firm polymer type compound which is embedded in the recess: 

Looking around the (boarding) hangar I didn't find anything, and I asked if anyone knew anything (no reports). I did not do a thorough post-flight this weekend flying in, so I think it is probably lying in the woods of Eastern WA or northern ID. 

I don't know anything about the design or installation of these gauges. I am guessing it is magnetically-coupled. The plug shown in these photos seems to seal the top of the tank... as far as I can tell. I watched it early in flight (about 1 hr 40 min) to see if anything siphoned. I saw little bubbles that sat there, which I think was cloud condensation or TKS fluid (felt like the latter after landing). No fuel smell in the recess. 

What to do? 

- how is this repaired? 

- do I need to worry about water ingress?
 

Thanks for any tips!
David

[LANCECASPER]

 

 

[amillet]

It’s just latex that glued it into the bowl. 

[1980Mooney]

12 hours ago, dkkim73 said:

Pre-flighting this morning, I noticed my left wing fuel gauge was missing. I saw a cloud-like white mass which looked like chewing gum but seems to be a firm polymer type compound which is embedded in the recess: 

I don't know anything about the design or installation of these gauges. I am guessing it is magnetically-coupled. The plug shown in these photos seems to seal the top of the tank... as far as I can tell. I watched it early in flight (about 1 hr 40 min) to see if anything siphoned. I saw little bubbles that sat there, which I think was cloud condensation or TKS fluid (felt like the latter after landing). No fuel smell in the recess. 

What to do? - how is this repaired? - do I need to worry about water ingress?

When you say "do I need to worry about water ingress?" do you mean into your fuel tank? Into tank - NO.  There is no way for it to get into the tank. The pick-up and sender assembly is built into a solid piece of aluminum which is installed into a wing access pane. The gauge uses a magnetic coupling to the pick-up. 

 

 

But the reason it popped out is most likely because water got behind the dial and into that cavity.  Once you get high and hit freezing temps the water froze and expanded loosening the glue joint. Compounding the problem was that the glue was only in contact with part of the back of the dial  It probably did it many times until the glue joint failed.  It then was sucked off in flight.

All that you need to do is get a new dial.  You do not need to touch the pick-up/sender or wing access panel. The dial is easy to install but you may have trouble finding a new one.  There are different dials for different Mooney models because of different fuel capacities. When I needed one Lasar was out, but I had luck finding it at Don Maxwell's.

• Clean out that old white latex. 
• Install the new one with RTV. 
  • There is a a tang on the back of the dial to insure that you align it properly - It is "fail safe" - there is only one way to put the dial in.  You can see the corresponding alignment notch in your picture.
  • Make sure to use enough RTV to completely fill the cavity when the gauge is pressed in without leaving air pockets. 
    • The RTV will fully contact the back of the dial for maximum adhesion and not allow any water behind the dial
    • It may be a little trial and error (don't fill the cavity to the top before pressing dial in - try about 2/3) and some excess RTV will likely ooze out, but just wipe it off after fully pressing the dial in.  After pressing in hold your thumb on it for a bit - if there is an air bubble compressed in the RTV, it will try to expand and raise the gauge.  You can just set something on it like a wrench while it sets.

https://lasar.com/gauges/dial-face-880024-009

 

 

Edited July 5 by 1980Mooney

[ArtVandelay]

Is there a reason not to have the RTV entirely fill the cavity so no water can get in between and pop the gauge out when it freezes?

[LANCECASPER]

@Patrick Horan just went through this on his Bravo (N9153Z). Did you find a gauge?

[dkkim73]

Thank you very much indeed, guys, esp. @1980Mooney for the explanatory diagram. That makes a lot of sense, as I couldn't see how it would otherwise couple the position, and a non-sealed design wouldn't make as much sense. 

Mechanism of failure also makes sense, esp. since there is some obvious space back there... like water in rock cracks! 

The dial on the other (surviving) side suffers from condensation in the dial capsule. Has anyone seen that and fixed it themselves? (find the hole, dry it out, re-seal it). Edit to clarify: asking as it is now clear there's no downside to removing it for inspection and re-setting. I somewhat lean toward just replacing it on general principles (more reliable?), as those gauges seem very reliable and straightforward, and are a nice cross-check on the (less reliable I think?) reported levels from the electrical senders. 

David

[natdm]

1 hour ago, LANCECASPER said:

@Patrick Horan just went through this on his Bravo (N9153Z). Did you find a gauge?

He found a different gauge with different markings but works. 

[DonMuncy]

Condensation is a regular problem. Apparently Rochester does not have their seal process good enough. They make these for many applications and might not plan well enough for altitude changes. 

You might try popping the dial out and placing in some dessicant for a while and see if that takes the condensation out. 

[dkkim73]

@DonMuncy that's a good idea. I suppose I could cover the edges with a sealant afterwards. Will let you all know if I come up with anything illuminating. 

[dkkim73]

@natdm @Patrick Horan Patrick, did you end up re-marking the dial in any way? I suppose without even cutting it you could come up with an arc label and laminate it over the top. 

[PT20J]

I bought some 3M clear tape and covered each dial with a piece of it. It helps keep the moisture out and should keep it attached to the wing

 

[Patrick Horan]

On 7/5/2024 at 10:39 AM, LANCECASPER said:

@Patrick Horan just went through this on his Bravo (N9153Z). Did you find a gauge?

I did find a similar gauge that Rochester makes. It is not exact but it is close. There is slight modification that I had to do in which I had to cut and file down smooth the plastic screw tabs. The gauge number is 5-1792. This website seems to have it. I don't know the validity of this website, but I believe they have it. 

https://www.rrclllc.com/store/Rochester-5323S01792-JR-size-direct-read-dial-capsule-p315526097

15 hours ago, dkkim73 said:

@natdm @Patrick Horan Patrick, did you end up re-marking the dial in any way? I suppose without even cutting it you could come up with an arc label and laminate it over the top. 

I didn't remark the dial. I just mounted it off center. It's kinda tough to explain without a picture. The replacement dial doesn't have the markings like they would on the mooney ones. Instead they have E, 1/4, 1/2, 3/4, F. So I looked at the old dial on the other wing and realized that 22 gals indicates 1/2 full. I noticed 22 gals isn't exactly lined up with the middle like the new dial when it indicates half full. So I just glued the new dial and turned it to the right slightly 

[Steve Dawson]

I just posted about these on another thread on MS. I believe I bought mine a year ago on eBay or through Amazon. The tabs on the side are easily removed with some snips and then file off the leftover tang. These will work until the replacements are available. 

[PT20J]

1 hour ago, Steve Dawson said:

I just posted about these on another thread on MS. I believe I bought mine a year ago on eBay or through Amazon. The tabs on the side are easily removed with some snips and then file off the leftover tang. These will work until the replacements are available. 

That's probably the best you can do. The standard Rochester gauges use a screw through the tab to attach the dial and the whole assembly mounts on top of a tank. Mooney obviously wanted a version that would mount flush with the wing and so the Mooney dials are glued in with RTV -- some better than others evidently.

[Larry]

Those that have used the %-1792 mentioned above.  Does it sit flush to the wing?  The drawing shows a bump on the rear (see drawing below).

[dkkim73]

Received the Rochester 5-1792 (on the face) today, long # on back 5323S01792. These are the ones @Patrick Horan reported on. 

Measuring the angular distances between various reference points, they are slightly off what I am seeing on the 880024-009 Mooney-dialed version (for the 89/100 usable long-body tanks). 

I am considering whether to install as Patrick did to get a ballpark (setting 1/2 at 22gal as he did), at least for now, or cut-one open and attempt to re-face it. There is a seam around the rim, I cannot tell if it was glued, heat-fused, etc. I'm sure it can be opened with the right tools or patience. 

Has anyone opened these up yet? I didn't see any mention of such on the other threads. 

Alternatively, an arc-shaped sticker overlay on the top surface might be a more precised workaround. Esp. with @PT20J's transparent 100-mph tape trick!

 

[dkkim73]

On 7/7/2024 at 4:14 PM, Larry said:

Those that have used the %-1792 mentioned above.  Does it sit flush to the wing?  The drawing shows a bump on the rear (see drawing below).

I think that drawing is a different variant than the link above. These are also sold with Hall Effect-based electronic transducers to generate signals for remote monitoring. See the photos in my last post for the back side of the dial Patrick discussed. 

[Pinecone]

I think I would install it so that Empty is Empty.  They develop a calibration table for all the other marks.

For my fuel stock, I printed out the conversion and laminated it.   I have the actual gallons, Fuel Hawk readings, Fuel Stik readings, actual inches, and wing fuel gauge.

I have Monroy tanks, so the wing fuel gauges are off anyway.

[dkkim73]

Thanks for all the specific tips. 

I experimented with cutting into the case and thought it would be more of a thrash to do well and get sealed back properly. 
So I went with an overlay approach. Compared photos of the original -009 gauge pattern, measured angles in ImageJ and cobbled together a dial image in Powerpoint's vector draw facility, scaled as able and printed some dials out (someone with a real drawing program could do much better!). 

Used a dime to cut out the center and lined up the capacities at 22.25gal and "1/2" (estimated of course). Used clear repair tape to apply it and then installed in the plane as per prior advice above using RTV 108 silicone. 

Photos attached. I'm still going to either clean up the excess silicone or fill it carefully in flush, and then follow up with @PT20J's tape approach over the top. 

Also attached is a PDF of my Powerpoint of the dial faces (it won't let me upload the .PPTX here, can send if anyone needs it). I had to play with print scaling to get the sizing right (I put a sizing rectangle on the image to help with this). Just in case someone else has the same problem. 

It's not perfect but I think pretty usable and an excellent stopgap measure until the correct gauges become available again. I would imagine the approach would work with other dial ranges as well. 

 

Wing fuel gauge overlay.pdf

[PT20J]

Pretty cool. We’re all going to have to get creative about repairing our airframes since some of these original parts may never be available again.

[DonMuncy]

Did you get an STC for that? 

[N201MKTurbo]

58 minutes ago, DonMuncy said:

Did you get an STC for that? 

I think those fall under NORSEE or owner produced parts. I don't think the wing mechanical fuel gauges are on the type certificate.

[Ragsf15e]

14 hours ago, dkkim73 said:

Thanks for all the specific tips. 

I experimented with cutting into the case and thought it would be more of a thrash to do well and get sealed back properly. 
So I went with an overlay approach. Compared photos of the original -009 gauge pattern, measured angles in ImageJ and cobbled together a dial image in Powerpoint's vector draw facility, scaled as able and printed some dials out (someone with a real drawing program could do much better!). 

Used a dime to cut out the center and lined up the capacities at 22.25gal and "1/2" (estimated of course). Used clear repair tape to apply it and then installed in the plane as per prior advice above using RTV 108 silicone. 

Photos attached. I'm still going to either clean up the excess silicone or fill it carefully in flush, and then follow up with @PT20J's tape approach over the top. 

Also attached is a PDF of my Powerpoint of the dial faces (it won't let me upload the .PPTX here, can send if anyone needs it). I had to play with print scaling to get the sizing right (I put a sizing rectangle on the image to help with this). Just in case someone else has the same problem. 

It's not perfect but I think pretty usable and an excellent stopgap measure until the correct gauges become available again. I would imagine the approach would work with other dial ranges as well. 

 

Wing fuel gauge overlay.pdf 47.8 kB · 3 downloads

That’s well done!

[dkkim73]

5 hours ago, DonMuncy said:

Did you get an STC for that? 

Why, of course! In fact, PM me if you're interested in purchasing it. 
It's not quite the build quality of the visors, but could be improved! Perfect business opportunity for an entrepreneurial gentleman such as yourself. 

(oh, the internet has made me sell my soul...)