Mooney M20K 36 Gallon Fuel Dipstick

[Q The Engineer]

Guys,

Has anyone found a source for a 36 gallon tank fuel dipstick for a M20K?  I've been working paint sticks and I've not been happy with the wood sticks available.  I can't find any that are absorbent enough to provide a reliable mark on the stick. Has anyone found anything like the J-Air dipsticks available for 172's? 

Thanks,

Aaron

[PeteMc]

1 hour ago, Aaron Q said:

36 gallon tank fuel dipstick for a M20K

Does your K not have the in-wing fuel gauges?  I find them to be extremely reliable.

 

[Q The Engineer]

3 hours ago, PeteMc said:

Does your K not have the in-wing fuel gauges?  I find them to be extremely reliable.

 

Hi Pete, it has them, I just don't trust them yet.  I want to use a dip stick, check the wing gages, and check the instrument gages for consistency.  

[Q The Engineer]

3 hours ago, mike261 said:

check the download section, I put one in there last week.

Mike

 

Thanks a ton Mike, I found it.  What are you using for dowel material? The paint sticks I've tried wick the fuel up and you don't get a clean fuel line on the stick.  Thanks!

[milotron]

How well does the dip stick work with the flappy things in there?

 

[carusoam]

Find the discussion where @Bob_Belville discussed the stick he used…. 
 

iirc it had something to do with his bee hive keeping skills…

His engineering skills were even better… so he may have covered what wood his bee hives were built from…

 

The M20K has the most challenging tanks to know…. There were soooo many variations over soooo many years…

Trust and verify!

Best regards,

-a-

[DonMuncy]

I made my dip from oak. If absorbs fuel plenty well to be able to read the level. I ran one tank out of fuel in flight, returned home and refilled the tank, 2 gallons at a time. I suppose one could take the position that each tank is dfferent and for better accuracy, you could have a stick for each side, but I am not that worried.

I would be glad to share the measurements, and could be induced to make a duplicate , but that would assume all 231's have the same tank size, shape etc.

[Andy95W]

4 hours ago, Aaron Q said:

The paint sticks I've tried wick the fuel up and you don't get a clean fuel line on the stick. 

It’s a paint stick, for Pete’s sake.  You might be expecting more accuracy than a free, home-made fuel stick is capable of providing.

This, BTW, is mine.  More than 10 years old and still looks brand new.  Free Lowes paint stick and ball point pen.

[carusoam]

Going to need instructions and a timer with that….  

1) Measure the least filled tank first…

2) Do not exceed 5 seconds in the tank before removing for reading…

Nice pic Andy!

Thanks for sharing it…

 

The wing site gauges are only accurate to 5gal lines….

Best regards,

-a-

[Greg Ellis]

This sounds stupid but not all paint sticks are created equal.  I had one that came with my airplane made by the previous owner.  Whatever the wood was that it was made out of showed a beautiful line when dipped into and then pulled from the tank, much like the one @Andy95W shows in his photo.  Well, mine broke and so I just went down to Lowe's and grabbed one of the freebies.  Well, it is made out of some cheap balsa wood or something.  When you dip the tanks with it, by the time you pull it out of the tank there is no line at all showing the fuel level.  A search through some old boxes of paint supplies at my house revealed another paint stick that works.  So, it seems that you need to find an older paint stick.  Whatever they make these new cheap ones out of does not work.  

I know, I know, this sounds stupid but I feel that the world will stop spinning on its axis if I did not post this important bit of vital information.   And, yes, this is me laughing at myself.

[midlifeflyer]

16 hours ago, Aaron Q said:

Guys,

Has anyone found a source for a 36 gallon tank fuel dipstick for a M20K?  I've been working paint sticks and I've not been happy with the wood sticks available.  I can't find any that are absorbent enough to provide a reliable mark on the stick. Has anyone found anything like the J-Air dipsticks available for 172's? 

Thanks,

Aaron

If you are interested in J-Air, they make a universal Fuel Hawk you calibrate yourself. I calibrated one for a friend's light sport after being dissatisfied with paint dipstick results.

[Pinecone]

10 hours ago, DonMuncy said:

but that would assume all 231's have the same tank size, shape etc.

That is the issue, a LOT of different tank sizes and configurations from Mooney.  Then add in the Monroy tanks (with and without speed brakes).

Hmmm, I wonder how many different tank capacities there are for what is the same basic airframe???

Hmm, my 252 POH says 39.3 gallons per side.  But I am thinking (airplane is at Fly RPM for annual), that the fuel tank placards say 37.x gallons.  Monray fillers are placarded for 14.8 gallons (I have speed brakes).

[Q The Engineer]

2 hours ago, mike261 said:

not sure, its a hardwood dowel from home depot...gives you a few seconds to read it.

mike

Thanks!

[Q The Engineer]

11 hours ago, DonMuncy said:

I made my dip from oak. If absorbs fuel plenty well to be able to read the level. I ran one tank out of fuel in flight, returned home and refilled the tank, 2 gallons at a time. I suppose one could take the position that each tank is dfferent and for better accuracy, you could have a stick for each side, but I am not that worried.

I would be glad to share the measurements, and could be induced to make a duplicate , but that would assume all 231's have the same tank size, shape etc.

Thanks Don! 

[Q The Engineer]

10 hours ago, Andy95W said:

It’s a paint stick, for Pete’s sake.  You might be expecting more accuracy than a free, home-made fuel stick is capable of providing.

This, BTW, is mine.  More than 10 years old and still looks brand new.  Free Lowes paint stick and ball point pen.

The sticks I've tried have more wicking than yours.  I plan to try a hardwood dowel next.  Thanks for sharing. 

[Q The Engineer]

1 hour ago, Pinecone said:

That is the issue, a LOT of different tank sizes and configurations from Mooney.  Then add in the Monroy tanks (with and without speed brakes).

Hmmm, I wonder how many different tank capacities there are for what is the same basic airframe???

Hmm, my 252 POH says 39.3 gallons per side.  But I am thinking (airplane is at Fly RPM for annual), that the fuel tank placards say 37.x gallons.  Monray fillers are placarded for 14.8 gallons (I have speed brakes).

My 231 calls out 36 per side.  We drained them and filled at the pump confirming 36 gallons. 

[GMBrown]

Aaron- Is the top of the fuel in your tank, when full, below or above the flap?  I f above, how far?  To the wing???  I also have 36 per side, but am loath to fill above too far above the flap.

[DanM20C]

My K is a 79 so I have 36gal per side.  The few times I have ran a tank dry I was able to put nearly 38gal in.  It seems like the tanks size is the same as the later 231's of 75.6 usable.  Does anyone know if there is a mechanical difference in the tank or is it a certification change? 

I don't have a fuel stick for my K but I did make one for my C.  I used a hardwood (probably oak) dowel and used the dimensions found here to mark the gallons.  I used my lath to turn the marks on the dowel, it was incredibly accurate and very easy to see.  I've wanted to make one for the K but the filler flap is a pain, I'm installing the visual float gauges in the next few months. 

Cheers,

Dan   

[Q The Engineer]

4 hours ago, GMBrown said:

Aaron- Is the top of the fuel in your tank, when full, below or above the flap?  I f above, how far?  To the wing???  I also have 36 per side, but am loath to fill above too far above the flap.

I may have screwed up.  I'm reading the POH now and it calls out 80 gallons, 72 gallons usable.  The fuel level is above the flap quite a bit.  I fill it to the tank flapper which is about 1.5" from the top of the wing.   

[Q The Engineer]

2 hours ago, DanM20C said:

My K is a 79 so I have 36gal per side.  The few times I have ran a tank dry I was able to put nearly 38gal in.  It seems like the tanks size is the same as the later 231's of 75.6 usable.  Does anyone know if there is a mechanical difference in the tank or is it a certification change? 

I don't have a fuel stick for my K but I did make one for my C.  I used a hardwood (probably oak) dowel and used the dimensions found here to mark the gallons.  I used my lath to turn the marks on the dowel, it was incredibly accurate and very easy to see.  I've wanted to make one for the K but the filler flap is a pain, I'm installing the visual float gauges in the next few months. 

Cheers,

Dan   

Cool thanks Dan.  I just checked the POH and it calls out 80 gal total, 72 gal usable.  The wing placards say 36 gallons.  

[kortopates]

8 minutes ago, Aaron Q said:

 The fuel level is above the flap quite a bit.  I fill it to the tank flapper which is about 1.5" from the top of the wing.   

The factory says "Full" is to to the base of the flapper valve, but not everyone can get the rate capacity stopping there. 

I am pretty sure that the only thing that changed through the different K's was the amount of non-usable fuel with each update - not tank dimensions. 

[Q The Engineer]

2 hours ago, kortopates said:

The factory says "Full" is to to the base of the flapper valve, but not everyone can get the rate capacity stopping there. 

I am pretty sure that the only thing that changed through the different K's was the amount of non-usable fuel with each update - not tank dimensions. 

Thanks a ton man.  My POH for N231NJ calls 80 gallons total, 72 gallons usable.   I have the POH for N654JB and it calls out 78.6 gallons total, 75.6 gallon usable.  I have the POH assigned to Don Watson of Continental during development of the 252.  It's a 231 POH and it calls for 80 gallons total, 72 gallons usable like mine.  I have another POH assigned to Don Watson during development of the 252.  Its a 252 POH and calls for 78.6 gallons total, 75.6 gallons usable.  

So I have 2 each that agrees.  It makes me wonder of the 231 tanks were measured again during 252 development generating the second set of number?  Does anyone know?  I can't imagine the tanks are actually different.  When I get a minute I'll check part numbers on the wings between the two. 

Thanks for everyone's help. 

M20K-POH-N654JB.pdf

[kortopates]

1 hour ago, Aaron Q said:

So I have 2 each that agrees.  It makes me wonder of the 231 tanks were measured again during 252 development generating the second set of number?  Does anyone know?  I can't imagine the tanks are actually different.  When I get a minute I'll check part numbers on the wings between the two. 

I agree with your observations. Unfortunately there is no part no for tanks in the wings, nothing in the IPC to give you exact dimensions of wetted fuel areas that I know of. We'd need access to Mooney drawings.

[Q The Engineer]

5 minutes ago, kortopates said:

I agree with your observations. Unfortunately there is no part no for tanks in the wings, nothing in the IPC to give you exact dimensions of wetted fuel areas that I know of. We'd need access to Mooney drawings.

I don't have access to the Mooney drawings.  It would be interesting to know.  I'll ask Minnis the next time I talk to him.  Thanks for the info. 

[Pinecone]

But the tanks are based on the same wing design.  So unless they moved the spar ir ribs, the volume should be the same.