Fuel Cap O Rings

[M20F]

Hi All,

Anyone able to tell me best place to buy and the part # for the o-rings on standard 1967 M20F fuel caps. The smaller o-ring seems to be good as the sunken area of the cap is always full of ice/water, the larger o-rings though appear to be leaking all of a sudden so want to replace them.

[jetdriven]

Easiest way is call your favorite MSC.

[sreid]

Or order 2x of MS29513-010 and 2x of MS29513-338 for about $4 from Aircraft Spruce. (reference Mooney SB M20-229A)

[jwilkins]

You really should replace both as a set; the inner post O ring is not under compression as the large outer ring and is.

[Jerry 5TJ]

They are an annual (or at least every other) annual item. Takes about 5 minutes to change the two rings on each cap.

Those O rings really do their work. When I bought my "C" the small inner O ring was missing on one side, and after a week-long stay parked outdoors in E Texas with heavy rains I drained at least 1 quart from that tank. It took about 25 fuel sampler cup-fulls to get to clear blue fuel.

If it rains on your bird, and there is NOT a puddle in the top of the gas cap recess, look out for water in the fuel.

[M20F]

Thanks everyone!

[danb35]

Or, upgrade to the blue flourosilicone O-rings that last a lot longer. See http://csobeech.com/fuel-caps.html. Bonanzas use the same fuel caps our Mooneys do.

[DrBill]

I got mine at Aircraft Spruce (as above). Worked great. Bought a bunch and sold then with the old caps a month ago.

BILL

[1964-M20E]

Or order 2x of MS29513-010 and 2x of MS29513-338 for about $4 from Aircraft Spruce. (reference Mooney SB M20-229A)

Do you know if these are the same O-rings for the caps withe the O&N bladders?

[sreid]

Do you know if these are the same O-rings for the caps withe the O&N bladders?

I don't have any idea if they are the same or not.

[Marauder]

Do you know if these are the same O-rings for the caps withe the O&N bladders?

My question as well! The price for the O&N cap O rings are over $100!!!

[DrBill]

OLD bladders used the SHAW caps. The new bladder-caps have locks and are slightly smaller. I'll measure the big one my next trip to the airport. The small one is internal and I'm not ready to open it up yet.

BILL

[jetdriven]

The O-rings for the bladder Shaw caps are only available through O&N. The price is over 100$ as well.

[DrBill]

They have to be a standard size. Perhaps metric but must be a standard size. They switched to these new caps because it's much cheaper for them for the new caps than new SHAW caps.

That's what they told me when I got mine done.

BILL

[jetdriven]

The price for the Shaw Aero fuel caps went up to $2,500 EACH and O&N had to change their STC and fuel filler ring to use a different cap a couple years ago. Some Huckleberry's bought Shaw and the first thign they did was quadruple the prices. Then double them again. The Shaw cap is a 50 PSI Learjet item and the O-rings are available through Aircraft Spruce. I discovered this after reading the invoice, but they are unique to that cap and the price at Spruce is the same. over 100$ for a set of 4.

[DrBill]

My old SHAW (standard Mooney Caps) had O-rings I got at Aircraftr Spruce.. Standard MS29513 parts,

My new O&N Bladder caps use MS29513-230 2.75 in OD and 1/8 in in DIA. I just measured them with calipers.

I did not dissassemble to find the size of the internal ring.

O-RINGS USA (http://www.oringsusa.com) had the best selection and price ($0.60) each $5.00 minimum order.

I think when I get some time I'll find the size of the internal one and order a few sets and change them every annual.

I just looked up the Shaw 457-370 part.. WOW.. topside looks BEEFY.. Bottom is vary similar to old part. I bet it uses standard fuel resistant O-rings..

BILL

[jetdriven]

The Shaw 450-370 cap uses a CA38241 which is $49.75 from Spruce, each. It also fits a Cessna Citation and Beech King Air and 1900D fuel cap. I have not found a source for the small inner one. THe good thing is they last quite a few years. Blue fluorosilicone o-rings are very durable.

http://www.aircrafts...?clickkey=16470

www.pmaproducts.com/supplements/CA38241.pdf

[DrBill]

That flourosilicone material is what makes it not cheap. I've seen them for as low as $43 ea. They will definitely outlast any "rubber" Oring.

BILL

[jetdriven]

I bought a set of Beech flourosilicone O-rings for my Mooney. They didn't fit. They were only 35$ shipped for a set of 4. There are things at play here, but they are not supply and demand driven. There is no reason they should be 134$ a ser delivered.

[DonMuncy]

Am I understanding this right. More than eight dollars apiece for 'O" rings. When perfectly good fuel resistant ones are available. It seems to me that we have been using the "old" ones for years and not having any leakage problems so long as they are changed at annual. And it is my inderstanding that some IAs read the AD to require annual changes of the "O" rings anyway. I don't think there is an exception for blue ones. At those prices I could change mine 4 times a year. If we could pop in the new ones and not worry about them for 5 years, I might be convinced. Maybe I'm missing something.

[jetdriven]

Don, our blue o-rings lasted 21 years before being changed, and they were not leaking, i just felt like changing them proactively. Had i known the price beforehand I might have gone longer. 135$/21 = 6$ a year and another 400$ in labor (.5 hr a year) saved. I still think it is a ripoff, but economically speaking, the blue O-tings at 135$/set are far cheaper.

You Mooney guys with the standard caps, the blue O-rings are 35$ a set. A no-brainer.

[DonMuncy]

Byron,

Did you have to fight with your A&P/IA at annual. They are forever telling me they have to change them every year. In all honesty, they may have been telling me they have to inspect them, and merely change them because it is so cheap, it doesn't make sense to inspect and leave them in. If they are taking them apart to look (and presumably charging for that) are you really ahead with the ones with a 21 year life.

Another aspect. Is this price from an aviation source, or a generic O-ring source. Are all the blue ones that expensive.

[jetdriven]

Mooney M20-229A (AD 85-24-03) specifies inspection of the fuel caps for leakage every 100 hours or annual inspection. It does not explicitly say replace the fuel cap o-rings, but does specify to inspect for leakage of water and "the sealing capability of the fuel cap should be checked periodically" and says to replace the o-rings if deficiencies are found. I know Don Maxwell and others take this to mean replace fuel cap o-rings every year as a preventative measure, and I agree completely with that. However, the blue flourosilicone o-rings are much more durable and will last longer than one year, and may not need replacement annually. They are more expensive than the MS o-rings, but they are still cheap.

In our case, we have the O&N Citation style fuel caps, which are not affected by the AD per se, but we changed them proactively since we occasionally park the plane outside, and leaking fuel caps result in sudden death. Ours were not leaking and had I known about the 100$+ cost, I would have waited longer to change them. I cut one off the fuel cap, and after finding out the Beech o-rings did not fit, learned the lesson the expensive way.

The blue o-rings can be sourced from oringsusa.com and meet the standard for fuel cap o-rings. They meet the MILSPEC for o-rings. Here is much more info from CSOB.com

http://www.csobeech.com/fuel-caps.html

[Marauder]

Mooney M20-229A (AD 85-24-03) specifies inspection of the fuel caps for leakage every 100 hours or annual inspection. It does not explicitly say replace the fuel cap o-rings, but does specify to inspect for leakage of water and "the sealing capability of the fuel cap should be checked periodically" and says to replace the o-rings if deficiencies are found. I know Don Maxwell and others take this to mean replace fuel cap o-rings every year as a preventative measure, and I agree completely with that. However, the blue flourosilicone o-rings are much more durable and will last longer than one year, and may not need replacement annually. They are more expensive than the MS o-rings, but they are still cheap.

In our case, we have the O&N Citation style fuel caps, which are not affected by the AD per se, but we changed them proactively since we occasionally park the plane outside, and leaking fuel caps result in sudden death. Ours were not leaking and had I known about the 100$+ cost, I would have waited longer to change them. I cut one off the fuel cap, and after finding out the Beech o-rings did not fit, learned the lesson the expensive way.

The blue o-rings can be sourced from oringsusa.com and meet the standard for fuel cap o-rings. They meet the MILSPEC for o-rings. Here is much more info from CSOB.com

http://www.csobeech.com/fuel-caps.html

There have been a lot of "caps" being thrown around here (pun intended). My bladders were installed in 1992. I am guessing I have the old style Shaw caps. Are these the $49 o rings on Aircraft Spruce? It sounds like there are new style caps for the bladder system. Anyone have a picture of what they look like?

My IA inspects my o rings every time I bring the plane in. I asked about changing them out on a regular basis and he told me that they were expensive and only needed to be replaced if they began to wear (I keep my plane hangared so that probably helps). I too like to be proactive. If the new style caps are available, can they be retrofitted on the older style bladder system or is the hole actually different?

[danb35]

Mooney M20-229A (AD 85-24-03) specifies inspection of the fuel caps for leakage every 100 hours or annual inspection.

More specifically, the service bulletin "requires" 100 hr/annual inspection, but nothing in the terms of the AD does. Some IAs, including Maxwell, take the position that the AD's reference to the SB for the "how" also makes the "when" of the SB mandatory; I can't see any way the AD does that. Mandatory or not, though, regular inspection of the O-rings (including the inner ring) is definitely a good idea--water in your fuel is a Bad Thing . There's nothing out there requiring or recommending periodic replacement of the O-rings.