Fuel contamination!!

[ChristianGodin]

The Passenger side of my Mooney 201 fuel tank is contaminated with water as soon as the airplane is outside under the rain for a while. Can it be the seal of the fuel cap? Where can I get new seals?

Thank You

[M20F-1968]

2 seals need to be replaced:  1 n ouside diameter of fuel cap, 2nd oround inner shaft.  Needs to be done annually and relogiously.  This IS a safety of flight issue.  Contact MSC for parts.

John Breda

[M20F-1968]

2 seals need to be replaced:  1 on ouside diameter of fuel cap, 2nd around inner shaft.  Needs to be done annually and religiously.  This IS a safety of flight issue.  Contact MSC for parts.

John Breda

[ChristianGodin]

Thank You John

[ChristianGodin]

I never buy parts myself, a well known mecanic shop in my area but not specialised in Mooney is taking care of the airplane and I naver save on that. But I am starting to loose confidence in them!

Is MSC a parts distributer? Am I allowed to changed those seals myself? What is their phone number?

Thank You...

[danb35]

You are not allowed to change the O-rings yourself and sign off on it, at least under US rules.  They are standard mil-spec O-rings, not a special Mooney part; see service bulletin M20-229 on mooney.com for the details and part numbers.  That service bulletin recommends that the O-rings be inspected annually, and that the enter one be lubed periodically with a little Tri-Flow (just a quick shot of that down the center shaft), but that recommendation is not regulatory in the US.  There is an AD, though, that requires the inspection be performed once.  Neither the SB nor the AD requires replacement of the O-rings on any particular schedule, though if you're using the standard O-rings, it's probably a good idea.

Many owners find that blue flourosilicone O-rings provide superior service to the factory specified parts.  The part numbers are M25988/1-010 and M25988/1-338.  You can find more information, and sources, at http://csobeech.com/o-Rings.html (as well as a link to a good write-up on changing them).

MSC is a Mooney Service Center, but again, there's no reason to buy the O-rings from one, as they're standard mil-spec parts.

[John Pleisse]

I have my O-rings done every annual. And still, vigilance is required.

[JaredDavis]

Does anyone know the MS part numbers for the 457-1015 O&N caps?

[Piloto]

The O-rings may not be the culprit but rather the fuel cap shaft nut adjustment. This should be adjusted so it requires some effort to set down the cap lever. You can verify any leaks around the cap by spraying bubble soap or SD-20 around the cap perimeter and then blowing air by mouth into the tank vent. Check for bubbles around the cap perimeter and center shaft. If after replacing the O-ring you still get bubbles the leak is comming thru the cap adapter ring rivets. These will require to be sealed with PRC sealant. 

José

 

[jetdriven]

Any o&n fuel cap o-rings have to be ordered through o&n.  They specified a Learjet cap and the o-rings are 100$.  Upside is they are the blue fluorosiicone O-rings and mine were 20 years old when I replaced them.  Anyone that tellls you fluorosilicone is not aircraft grade is wrong. 

[BigTex]

I was under the impression that SB M20-229 didn't apply to O&N Fuel caps since they're a different design.  Does anyone if that's the case?

[Kwixdraw]

For the O&N caps you will have to determine what you really have.  The caps were supposed to be replaced in the AD on the early bladder conversions but there was an alternate means of compliance allowing the flush caps to stay in place.  Look on their website and you'll be able to see what to do.