Top of Wing Fuel Gauges. Need advice.

[Jer]

Folks:

My "89 M20J, which I bought about 5 or 6 years ago, has a fuel gauge on top of each wing.  When I bought the plane, they were both clear and easy to read.  Since that time, one of the faces has become quite obscured.  I made the probably incorrect assumption that my tie-down position subjected one more than the other to harsh sun.   I assumed the face was cloudy as some automotive headlights get, and so I bought some plastic polishing compound and tried to buff it out.  In doing this , it became apparent that it was not merely a surface condition, but rather the face was discolored through and through.  The material now seems to be somewhat soft.  I am suspicious that the material is being degraded from the inside by contact with fuel.  Has anyone had any similar experience?  Any suggestions for a path forward would be welcome.

Jerry

[larryb]

At least a few years ago these weren’t that expensive. My shop just replaced one that was cloudy.

[0TreeLemur]

14 minutes ago, larryb said:

At least a few years ago these weren’t that expensive. My shop just replaced one that was cloudy.

Good to know.  The one in our J are almost impossible to read too.  The plastic is badly crazed on both.  It looks like they might just be held in with a snap ring?   Or, did they have to remove the top panel from the tank?

[DonMuncy]

Unless there is a breakage somewhere, fuel can not get into the gauges. The gauge reads from a magnetic field between the gauge and the underlying part built into the panel in the wing. The gauge is held in place with RTV of silicone material.

And yes, in aviation terms, they are cheap; if you mean a dial gauge that is worth about $5, and nowadays probably sells for $75 or so.

[Guest]

6 hours ago, 0TreeLemur said:

Good to know.  The one in our J are almost impossible to read too.  The plastic is badly crazed on both.  It looks like they might just be held in with a snap ring?   Or, did they have to remove the top panel from the tank?

They’re bonded in place with RTV silicone.

[N201MKTurbo]

You have to order them from Mooney. Like most parts, they don’t have them in stock. I suspect they wait till they have enough orders and then order a batch of them to be made. So get your order in and wait.

You can get generic capsules for boat tanks that read E to F. They have ears for hold down screws. It looks like they would fit if you cut the ears off. They would hold you over until you get the correct ones from Mooney.

[N201MKTurbo]

7 hours ago, Jer said:

Folks:

My "89 M20J, which I bought about 5 or 6 years ago, has a fuel gauge on top of each wing.  When I bought the plane, they were both clear and easy to read.  Since that time, one of the faces has become quite obscured.  I made the probably incorrect assumption that my tie-down position subjected one more than the other to harsh sun.   I assumed the face was cloudy as some automotive headlights get, and so I bought some plastic polishing compound and tried to buff it out.  In doing this , it became apparent that it was not merely a surface condition, but rather the face was discolored through and through.  The material now seems to be somewhat soft.  I am suspicious that the material is being degraded from the inside by contact with fuel.  Has anyone had any similar experience?  Any suggestions for a path forward would be welcome.

Jerry

It is a lot easier to mask it it you just pot a couple of stripes of tape across the capsule and cut around it with an X-acto knife.

[0TreeLemur]

Legend has it that certain fix-it-up chappies with a heat gun and infrared thermometer can restore crazed plastic windows using just the right amount of applied heat.  Aircraft windows, anyway.  A possibility on these gauge covers?

[Jer]

Folks:

I am sort of directing this to Don Muncy, who seems quite knowledgeable on this subject, but I would be happy to hear from anyone on the subject.  Is the face replaceable by itself, or is it integral with the gauge, which would indicate the entire gauge to be replaced?  What is involved as far as labor for the replacement?  If that little oval panel it is mounted to needs to be removed, and since this is a wet wing, does the tank need to be drained and then re-sealed?

Jer

[Fly Boomer]

@DonMuncy see above

[1980Mooney]

1 hour ago, Jer said:

Folks:

I am sort of directing this to Don Muncy, who seems quite knowledgeable on this subject, but I would be happy to hear from anyone on the subject.  Is the face replaceable by itself, or is it integral with the gauge, which would indicate the entire gauge to be replaced?  What is involved as far as labor for the replacement?  If that little oval panel it is mounted to needs to be removed, and since this is a wet wing, does the tank need to be drained and then re-sealed?

Jer

The "dial" is replaceable. - the plastic face alone is not replaceable.  Fuel doesn't usually damage the plastic however acetone does.  Some paint waxes/cleaners/sealers will soften the plastic.  My A&P did some paint touch up and got some overspray on mine - then he tried to clean it with a solvent used on Imron.  That turned it hazy.  I polished it clear again with toothpaste. However the rubbing caused it to loosen up and it flew off in flight.  Make sure you order the correct dial - see your J Parts Manual which is online and on Mooneyspace.  They differ between J, K and long bodies and short bodies due to fuel capacity.

DIAL FACE - 880024-005 — LASAR

 

https://www.google.com/url?sa=i&url=h

[DonMuncy]

I think this has already been answered. The dial itself can be easily pried out. It is just held in with RTV. You then need to scrape out the remainder of the RTV. Then put RTV on the new dial and press it in place. It is pretty obvious how much RTV to use. There is a small protrusion on the dial which fits into a small recess in the bottom section that insures it fits into the proper place. Put a piece of masking tape over it to hold it in place while the RTV sets. It should be about a 30 minute job.

[Jer]

Don:

I hate to be a pest, but his seems too good to be true.  Just to confirm, you are saying the oval plate does not need to be removed?  The entire thing can be accomplished from the top of the wing?  The six screws around the perimeter of the gauge attach only the lower assembly and not the dial itself?

Jer

[DonMuncy]

That is correct.

[1980Mooney]

16 minutes ago, Jer said:

Don:

I hate to be a pest, but his seems too good to be true.  Just to confirm, you are saying the oval plate does not need to be removed?  The entire thing can be accomplished from the top of the wing?  The six screws around the perimeter of the gauge attach only the lower assembly and not the dial itself?

Jer

If you read the MS discussion from 2018 on the same topic you will see the pictures of what it looks like after you pry the old gauge out and clean out the old RTV.

 

[0TreeLemur]

Q: Is the dial magnetically coupled to the mechanism in the tank?

[PT20J]

4 minutes ago, 0TreeLemur said:

Q: Is the dial magnetically coupled to the mechanism in the tank?

A: Yes.

[0TreeLemur]

18 hours ago, PT20J said:

A: Yes.

Kewl.

[0TreeLemur]

Lasar - Sold out.  Any other source?

[KSMooniac]

Maxwell likely has some on the shelf.

Sent from my LM-V600 using Tapatalk

[carusoam]

Be sure to get the correct P/N…

The same dial gets used for various Mooneys… but the artwork on the dial face will be specific to the tank it is used on… or the location of the dial in regards to the tank…

 

The crazing on these lenses seams a bit deep…. It is the wrong polymer for outdoor use…

Check with the headlight surface cleaners from the aviation aisle at AutoZone… they have a buff-out kit that could work if it is only a top surface issue… but, it looks like the cracks go further into the material, than just the top surface… bummer…

Pp thoughts only, not a mechanic…

Best regards,

-a-

[Jer]

I have a 2003 parts catalog as well.  The gauge is listed in the wings section, page 57-30-01 (photo attached) as 880011-505 with no effectivity notes but with the notation see 28-10-00, which was posted by user "1980Mooney".  That page shows the part number of 880024-5 with effectivity note /2.  I was not able to see what the /2 referred to.  Does anyone know the difference between the two part numbers?  The question is fairly moot, since I have not been able to find either.

[ArtVandelay]

I have a 2003 parts catalog as well.  The gauge is listed in the wings section, page 57-30-01 (photo attached) as 880011-505 with no effectivity notes but with the notation see 28-10-00, which was posted by user "1980Mooney".  That page shows the part number of 880024-5 with effectivity note /2.  I was not able to see what the /2 referred to.  Does anyone know the difference between the two part numbers?  The question is fairly moot, since I have not been able to find either.

/2 notes its held in using RTV and dial alignment should be noted before replacing.

[Irmin]

I have ordered the 880024-005 fuel sight gauge in JANARY at Lasar. They let me know that they do not produce the gauges but only sell it. So I asked Mooney about them with no encouraging outcome. They let me know that they do whatever they can to get those gauges in order with their management. Also they ensured me that those gauges are optional anyhow…

J A N U A R Y.

Who sells me a pair of them as both decided to leave the wing while flying

Thanks,
Irmin


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[Irmin]

I have ordered the 880024-005 fuel sight gauge in JANUARY at Lasar. Another one a few months later. After inquiring about delivering time Lasar let me know that they do not produce the gauges but only sell it. Point taken. So I asked Mooney about them with no encouraging outcome. They let me know that they do whatever they can to get those gauges in order with their management. Also they ensured me that those gauges are optional anyhow. So my speed tape solution lives on…

Just saying:


J A N U A R Y.

Who sells me a pair of them as both decided to leave the wing while flying

Thanks,
Irmin


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