Really Big Fuel Leak

[Jimhamilton]

I need advice for a rather significant fuel leak.  I own a M20K.  Last month I smelled some fuel in the cockpit.  I found the carpet in front of the rear seats soaked with fuel.  I researched this on the net and found that the most probable cause is the fuel quantity transducer behind the interior trim.  So I took a look and the area is dry.  I did not have the time to look anyfurther until yesterday (three weeks later).  The right tank is now dry.  It had seventeen gallons in it and now it is dry.  The left tank did not leak.  The carpet is still wet with fuel.  I have not seen any exteritor leaks or puddles of fuel.  Where did seventeen gallons of fuel go?  I have hired an A&P with little Mooney experience and would like to steer him to the most probable cause first.  I am thinking that the fuel tank selector valve might be suspect or maybe the fuel line from the right tank to the fuel selector valve.  Any advice is welcome.  Also, where did all that fuel go.  I know I had seventeen gallons and no puddles.  Could some of the fuel be trapped inside behind the rear seats.  (yikes ,don't light a match).  Thanks for your help, Jim Hamilton 

[OR75]

when avgas evaporates, if leaves very dark blue marks .... cannot miss these, remove the seats and look for those. 

[mooneym20d]

Three weeks is more than enough time for the fuel to evaporate. Are there any stains in the wheel well? I had a similar situation. Turned out to be leaking from the spar/rib joint at the most inboard and rear part of the tank. I had a local Mooney Service Center do the repair. The bill was $10,000. I got screwed. I would definately make sure you bring it to someone who specializes in Mooney fuel tanks.

[Jimhamilton]

The only evidence of the leak is inside the cockpit.  The wings and wheel well are clean.  Go figure?

[MooneyMitch]

Just a suggestion for you.  You might contact Greg Lehman at Advanced Aircraft Services in Troutdale, OR.  They are just West of Portland.  They are a Mooney Service Center fairly close to you.  Maxwell and Wilmar are excellent as well.

I've had great service from Advanced with a complete reseal on our E model last year and a recent leak repair on our R model.  I find Ed and Greg very fair, very efficient and very honest.

 

[carusoam]

On the interior the two most probable sources of leaks are the fuel level sender seal and the fuel line.  Often the fuel line is a rubber hose with decades of service.  They get brittle and crack.

Sounds like you have removed the interior panel and the blue tinted rug.  The suspected parts are readily visible with these pieces removed.  After that be on the look out for leaky screws, rivets seams, etc...

Don't forget to check the sump valves.  They are good for leaking out.  

Wherever 17gallons went.  It will leave a mark wherever it last evaporated from.  Light blue means it was thinly spread over a wide area.  Thick dark brown means it all dripped and evaporated from one spot.

Its there somewhere.

Best regards,

-a-

 

 

[paulbeck]

Hi Jim!

If you would like, you can call me tomorrow, at 320-295-1671 and we can talk about it!

 

Paul Beck

Weep No More, LLC

www.weepnomorellc.com

[MooneyMitch]

"Maxwell and Wilmar are excellent as well."  I meant to say Weep No More.  My apology to you Paul.

 

[Piloto]

Quote: Jimhamilton

I need advice for a rather significant fuel leak.

[Piloto]

Quote: Jimhamilton

I need advice for a rather significant fuel leak. I own a M20K. Last month I smelled some fuel in the cockpit. I found the carpet in front of the rear seats soaked with fuel. I researched this on the net and found that the most probable cause is the fuel quantity transducer behind the interior trim. So I took a look and the area is dry. I did not have the time to look anyfurther until yesterday (three weeks later). The right tank is now dry. It had seventeen gallons in it and now it is dry. The left tank did not leak. The carpet is still wet with fuel. I have not seen any exteritor leaks or puddles of fuel. Where did seventeen gallons of fuel go? I have hired an A&P with little Mooney experience and would like to steer him to the most probable cause first. I am thinking that the fuel tank selector valve might be suspect or maybe the fuel line from the right tank to the fuel selector valve. Any advice is welcome. Also, where did all that fuel go. I know I had seventeen gallons and no puddles. Could some of the fuel be trapped inside behind the rear seats. (yikes ,don't light a match). Thanks for your help, Jim Hamilton

[rocketman]

Until you figure out where 17 gallons has disappeared without an obvious trace, please don't fly the plane. 17 gallons does NOT disappear without a cause. Even after 3 weeks, there would be a very obvious odor of 100LL in the plane if it just puddled in the dependent location.

Question, was the plane left outside in an unsecured location?

[Jimhamilton]

The area is secure so no chance of siphoning.  The aircraft carpet is very wet with fuel, so there is no doubt I have a problem.  The aircraft is not airworthy ( will not be flown ).

These things must be addressed before I will fly it.

1.  Fuel leak fixed by A&P and documented in the log.

2.  Aircraft inspected by A&P for residule fuel and cleaned up.

3.  Carpets removed, cleaned and replaced.

Thanks to all of you for your advice.  Lucky for me it is Winter and I am not flying much. 

God Bless, Jim

[DaV8or]

Good news is, with that kind of loss, I'm guessing strongly that it's the fuel line hose behind the plastic panels. Easy fix, comparitively. If it is, do both of them on both tanks.