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bd32322

new 201 owner and need advice on some squawks

14 posts in this topic

Hi all - recently bought a 1987 M20J-LM (Lean machine) - have been very pleased with it so far. Put it in a Reiff Pre-Heater system for the north east winters.


Some issues I have had that I need some advice on are:


the wing walk seems to be some tape like substance that is glued onto the wing - and part of its coming off. Is it better to paint on a wing walk or replace with more adhesive stuff? Can I do the removal of tape and painting of the new wing walk myself (legally)? If so what glue remover should I use - anybody has done it?


My fuel gauge shows full although I know it should not be - has anyone seen that issue ?


Thanks


 

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It looks better painted in my opinion. A quart of Randolph wing walk paint will be plenty. make sure you stir the paint well to get the sand particles in suspension and protect the polyurethane paint. Apply anticorrosion primer.


 


 

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Quote: bd32322

My fuel gauge shows full although I know it should not be - has anyone seen that issue ?

Thanks

 

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thanks for your responses. I mean the electric panel gauge in the cockpit shows a full indication always. Some day randomly it will start working and it will show a correct indication - otherwise it always stays full

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Assuming the fuel gauge system is the same in your J as the K, if it reads empty with the master off, it is almost certainly the wiring to the tank sensors or a tank sensor itself at fault. 12v power goes to the gauge and the other wire on the gauge runs out to the tank. The tank has two sensors, one on the inboard side and one on the outer end. The inner gauge is insulated from the tank. The wire from the gauge runs into the inner sensor and on through it to the outer sensor, where it goes through the sensing element and to the ground. The net effect of this is that the average reading between the two sensors is received by the gauge, which theoretically gives an accurate reading regardless of the roll attitude of the plane.


What you are most likely seeing is that the wiring is getting to a ground somewhere. The most likely spot is the sensor on the inboard side, where the screws holding the sensor in the tank has insulated washers. If one of those fails, the voltage runs directly to ground and tells the gauge the tank is full.


If you are reasonably good tracing electrical, this is not a tough one to find. If not, anyone with knowledge of how the system works can do it relatively easily. Removing the side panel under the door (or in the anagalous spot on the pilots's side) will give access to the inner sensor. To access the outer one, you have to take an inspection panel off the underside of the wing just past the end of the fuel tank. It is a little tight in there, but not too bad.


If I can help, send me a PM or call.


Don 214 207-6744


 

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Sounds electrical as Don M. has pointed out.  Keep in mind, if the mechanical float devices have been sitting for a while they may need some exercise, as they may be stuck in the up position.  They are hard to reach but not impossible.  Give them some exercise and see if they are moving freely.  Two in each tank...


Best regards,


-a-

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-A-


Sounds like something I can do on my 20J LM too.  Can you tell me where you massage the floats?  Is it through the fuel cap or the inspection panel underneath?  I would think through the fuel cap inlet.


Russ

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As to a stuck fuel float; if your gauge reads full (when the tank is not), that would indicate both floats were stuck. I think this is highly unlikely. If one is stuck, the gauge will be substantially off (as the gauge will read the cumulative effect of both sensors), but not full. Ie, with one stuck up and the other working, with a half tank, the gauge would read 3/4, and when empty,it would read 1/2. 


I also think it highly unlikely a float would be stuck in any position other than up. The fuel level exerts a lot of pressure on the float. If you take one of these sensors apart, you find it is much like any rheostat. It has a lever operated arm which slides across a copper wire winding, making electrical contact at various distances along the wound wire. It would seem to take a lot of corrosion to overcome the force of the fuel pushing the float up. 


Don

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"Can you tell me where you massage the floats?" - TXBYKER


On my M20C, (26 gallons per side) I simply reached in through the fill neck.  You can probably use a mechanic's mirror on a stick to help with your planning.   The fill necks are pretty tight to reach through.


Best regards,


-a-


 

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Thanks a lot for the detailed info and special thanks to Don. I will check out the aircraft as mentioned in the posts and will PM/call if needed.


-b-

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Hi bd32322,

Did you ever get a resolution to this squawk? It seems that my right cluster gauge is now showing the same symptoms. The wing gauge is fine and I am managing fuel with a combo of time and flow as displayed by the fuel flow gauge. It would be nice to get fixed though, and if I can give my IA a place to start looking that would be a bonus.

Carl

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Back to the other question about the wing walk. I just removed the glued on stuff and replaced it with Randolph wing walk compound. I like the paint much better. I used a heat gun and heated while someone else pulled on the tape. It took a couple of hours to remove. I removed the old glue by using paint thinner to soften the glue and and old credit card to scape the glue. Painting on the new wing walk is easy and only takes an hour or so including the taping and prep. Lee

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Back to the other question about the wing walk. I just removed the glued on stuff and replaced it with Randolph wing walk compound. I like the paint much better. I used a heat gun and heated while someone else pulled on the tape. It took a couple of hours to remove. I removed the old glue by using paint thinner to soften the glue and and old credit card to scape the glue. Painting on the new wing walk is easy and only takes an hour or so including the taping and prep. Lee

Lee, This kind of report is only acceptable when accompanied with pictures ....  :)

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