Fuel Selector Woes

[cferr59]

I don't know what the original screen had, but the replacement screen that I installed (P/N 10543-1) did not have a rubber seal, nor did the screen I replaced.  It is sealed by the gasket pressing against it.  The Lasar gasket was about half the thickness of the one previously installed on my gascolator. 

It looks like your gasket was developing a similar tear pattern to mine on along the edge on the right side.  Interestingly, mine showed a little bit of blue staining, but did not leak in any significant way.

I just bought the Lasar gasket 2 weeks ago so I hope it is not from a bad batch.

 

[Vance Harral]

OK folks, here are some pictures of the gasket under a magnifying glass.  This is definitely not right.  The material is pitted, and has an "orange peel" or "chocolate cake" appearance.  My airplane partner says it looks and feels like foam rubber.  Either the material was crap to start with, or it was attacked by fuel, and/or the fuel lube used to assemble it.

When I get the new gasket tomorrow, the first thing I'm going to do with it is simply drop it in a jar of 100LL for a few days and see what it looks like after that.

 

Edited May 19, 2020 by Vance Harral
magnifying glass, not microscope

[Vance Harral]

1 hour ago, cferr59 said:

I just bought the Lasar gasket 2 weeks ago so I hope it is not from a bad batch.

 

I try not to be an alarmist.  But I think you better call LASAR first thing tomorrow, and ask if the gasket you received was from the same batch as the one Dan used to assemble our fuel selector.  If it was... or maybe even if it wasn't... I would not fly the airplane without pulling the selector bowl and inspecting the gasket.  Go look at the video in my OP again, and think about what happens if your gasket lets go in the air.

[Vance Harral]

Another hypothesis... the local shop drained our tanks into a portable fuel storage unit before pulling the selector to ship it to LASAR.  After reinstalling the overhauled selector, they simply put the fuel from the storage unit right back in our tanks.  This is a purpose built storage tank with a pump that's clearly labeled for 100LL, not some rusty bucket in the back corner.  Still, if there was Jet fuel or some other contaminant in the storage unit, it may have introduced contaminants into our fuel that ate the rubber seal.

This sucks.

[cferr59]

18 minutes ago, Vance Harral said:

I try not to be an alarmist.  But I think you better call LASAR first thing tomorrow, and ask if the gasket you received was from the same batch as the one Dan used to assemble our fuel selector.  If it was... or maybe even if it wasn't... I would not fly the airplane without pulling the selector bowl and inspecting the gasket.  Go look at the video in my OP again, and think about what happens if your gasket lets go in the air.

That is an interesting thought.  Unfortunately, mine has not been exposed to much fuel because I discovered a bad fuel pump when doing a leak check after reassembly.  I guess I will get in touch with them and see if they have any thoughts.  Looking at where your gasket is starting to fail, I feel that the failure mode for this would have been the same as my improper gasket had it managed to not completely split apart.   In this picture, the material in my hand is the outer part of the gasket which is what is starting to shear off in your pictures.  The gasket has turned inward on itself so the face you see is actually the inner edge (it is thicker than the replacement gasket so I think it is the wrong part). I'm not sure what would attack your seal that quickly.  I don't think Jet-A would do it.

My gascolator has a bit of blue staining, but I am surprised it didn't have a significant leak.

 

[MikeOH]

3 hours ago, Vance Harral said:

So I called Dan at LASAR and (politely) asked WTF.  His response was that he definitely replaced that gasket when he worked on the selector two weeks ago, but... this is not the first report he's had of this sort of problem, recently.

These gaskets are not generic parts.  They are Mooney-specific parts that come from the factory.  Yeah, I'm sure the factory just cuts them out of a sheet of butyl rubber or whatever, but the only legal source is the factory.  So one possibility is the factory has produced a set of crap gaskets that deteriorate in the presence of 100LL.  Maybe that caused cferr59's problem?  Dan claimed he'd be on the phone to Mooney immediately after hanging up with me.

The other possibility is that Dan is fibbing to me, to cover up shoddy work.  I can't discount that 100%, but I honestly have no reason to believe it could be true.  We've worked with LASAR in general, and Dan in particular, for over a decade with no issues.

Dan is overnighting us a new gasket, supposedly from a different lot of parts.  He's also still digging around for salvage fuel selectors.

Assuming we install the new gasket and everything holds... how many days/weeks/months do I stare at it on the ground before working up the gumption to fly with it?

I agree with your earlier comment that the seal just doesn't seem like it was only a few days old...maybe the if seal material is wrong and the 100LL got to it...but, it just looks 'old.'  Any chance you got someone else's gascolator?  You know, the innocent screwup where you got the other guy's pre-overhaul unit.  Any idea of the thickness of your old gasket versus a the 'new' one?

I think your idea of soaking the new gasket for several days is a great one!  No signs of swelling or deterioration would be a big confidence booster that leaks won't develop later after install.

[cferr59]

5 minutes ago, MikeOH said:

I agree with your earlier comment that the seal just doesn't seem like it was only a few days old...maybe the if seal material is wrong and the 100LL got to it...but, it just looks 'old.'  Any chance you got someone else's gascolator?  You know, the innocent screwup where you got the other guy's pre-overhaul unit.  Any idea of the thickness of your old gasket versus a the 'new' one?

I think your idea of soaking the new gasket for several days is a great one!  No signs of swelling or deterioration would be a big confidence booster that leaks won't develop later after install.

I tend to agree.  The indentation around the edge appears to be a permanant deformation and I would be surprised if the deterioration occurred in a few days.  Similarly, I don't believe that mine ended up like that between November and now.

[Vance Harral]

18 minutes ago, MikeOH said:

Any chance you got someone else's gascolator?

That's a very interesting question.  I'd say it's "unlikely", but I didn't record the serial number, and probably can never say for certain - one Duke's fuel selector looks pretty much like another.  I'll take a close look the next time I have it in my hands and try to recall any identifying features.  But my guess is that if there was even a remote possibility our selector had been accidentally swapped for another, Dan would have already thought of it.

 

11 minutes ago, cferr59 said:

Any idea of the thickness of your old gasket versus a the 'new' one?

I haven't measured, and not sure it'd be a meaningful measurement given the odd state of the gasket that was removed.  But the thickness of the deteriorated gasket looks "normal" to me, about on the order of 1/16".  It's comparable to the thickness of the  brand new one I installed a couple of months ago, just before I broke the selector, as well as others I've R&R'd in the past. 

[Hank]

@Vance Harral, take some similar closeup "before" pictures of the new gasket tomorrow, then soak and take more to see what changed. It could be "bad" upon arrival. BOA? 

[MikeOH]

3 minutes ago, Vance Harral said:

 But my guess is that if there was even a remote possibility our selector had been accidentally swapped for another, Dan would have already thought of it.

Perhaps..but, I have found one never thinks of things they've never considered

[Vance Harral]

For those following the saga...

Our "overnight" gasket actually took two days to arrive due to UPS delays in Louisville, but I did receive it yesterday.  Out of the bag, it measures 2" O.D. by 1.5" I.D. by about 1/16" thickness.  Weight is 0.05oz on my kitchen scale, but that's the limit of the scale's resolution so that's not a very reliable number.  I gently tugged on the inner and outer edges all the way around and found no cuts or defects.  Looking through a magnifier, you can see the material isn't what I'd call "pristine": it has some light fraying along the cut lines, and the surface is not perfectly smooth; but this is not different from anything I remember with previous good gaskets.

I dropped it in a clean mason jar with about a cup of 100LL drained from our left tank (the one that didn't get emptied by the leak).  Will report back here on what it looks like in a few days.

 

Edited May 22, 2020 by Vance Harral

[Andy95W]

That looks exactly like every gascolator gasket I’ve ever seen on an old Mooney.

I rarely replace mine.  I inspect it every annual when I clean the screen, and if the gascolator doesn’t leak, I put it back in and leave it alone.  Torqued properly with the new (lower) values it will last 10+ years and not leak.

[carusoam]

great thinking...

If it is absorbing fuel... it will probably...

• change dimensions in 3D... OD, ID, and thickness... as it expands.
• Change weight... It may hold a few grams of fuel... if it expands...
• Wipe dry, the outside gently... then squeeze it... see if acts like a sponge....
• put it in the warm sun... let it dry.... (use extreme care) see if it contracts, or gets lighter again...
• Don’t use an oven... if it releases fuel vapors... burning or blowing up would be bad... Especially if it is done in the finance administrators house...   
   

See if the hairs come off easily...

If they come off easy... it would be best to have them trimmed off, than have them fall off on the backside of the screen...

Fuel injectors and fuel jets (carb)are smaller than those hairs...

PP thoughts only, not a mechanic, or I would be trimming them off....

Best regards,

-a-

[M20F-1968]

Vance:

Here are some pictures and information I can make out from the fuel selector I own but know nothing about.  It looks very similar to an H&E.  

I cannot make out the manufacturer's name.  Perhaps it starts with "CHR"

The city of manufacture seems to be Solon, OH 44139

There is a part number CT - 2847 stamped on the label, but I may be missing part of it.

also stamped is   003  which may be the last part of a serial number

Manufacture date  3/92

It is build for a presumed low wing aircraft with a capacity of 27.4 gallons per side.  (? Piper)

Any ideas what aircraft this is from.

Could it be an H&E retrofit candidate?

John Breda

[Vance Harral]

Thanks to everyone for the continued comments, and thanks especially to John for posting pics of his spare.

John's spare appears to be made of anodized aluminum, as Anthony mentioned upthread.  Since John says his appears to be a copy of the H&E, my thinking is that the factory switched from the cast magnesium design of the Dukes selector to the anodized aluminum design of the H&E/others at some point, perhaps for exactly the reasons being discussed in this thread.

It's hard to say if John's spare could be a drop-in replacement in our aircraft without laying hands on it, but it appears to be at least roughly the correct configuration and dimensions.  If no one else chimes in with specific info, I'll try to get a hold of the factory after the holiday, and see if I can get some information on the exact selector in the retrofit kit.  The only reliable information I have about the retrofit kit at this point is a one-line e-mail from Stacy at the factory, who says it is p/n 940073-503, and that you order it through an MSC.  Internet searches on that p/n mostly turn up bogus autogenerated "catalogs" from dubious aviation parts suppliers.  But SWTA's web site does have a specific reference at http://www.swta.net/images/Retrofit_Kits.pdf, and my assumption is that's the $5K kit.  Can't find any images or sub-part breakdowns, though, so no telling what the actual selector in the retrofit kit is.  It also remains unclear to me what if any sheet metal work, re-routing of fuel lines, etc. might be required to use a retrofit selector.  Again, the pics of John's spare look like a drop-in replacement, but I wouldn't be surprised to learn some minor tweaking is required to switch from the Dukes to the H&E style.

[Vance Harral]

Today's update: after 3 full days soaking in 100LL, the new gasket expanded slightly, from exactly 2" O.D., to about 2 1/8" O.D.  This 6% dimensional change doesn't strike me as abnormal after soaking for that long, but happy to hear any comments the group has.  Thickness remains about 1/16", no noticeable change.  What's most interesting is a side-by-side comparison with the "old new" gasket - the one installed by LASAR that leaked.  If you take a look at the side-by-side photo, that gasket is substantially smaller at this point than the new one.  We didn't measure the defective gasket when it was pulled out, so I'm not sure if it came out of the selector that size, or shrank over the last week.  But the difference is enough that I continue to question whether the gasket that leaked was actually made of proper material.

The next photo in the sequence shows that the new gasket, with the slight expansion after soaking, initially seemed to be a little oversize for the selector body.  But after gently working it in, it seemed to lay pretty flat, so we proceeded with installation.  One interesting thing to note is that the wall of the selector body interior is not 90 degrees to the exterior.  It actually slopes a bit, i.e. it is actually a bit conical.  This tends to cause the gasket to have a bit of a cone shape as it's worked in to place.  Unsure if this is normal.  The whole thing is a little wonky and I'd feel better if it went together more smoothly.  But with everything worked gently in to place, the bolt that holds the bowl torqued to the low end of the 15-20 in-lb spec, and safety wire in place, it doesn't leak... at least for now.

We'll let this arrangement sit a few days and have the local A&P take a second look for signoff.  Hope to fly later this week if it continues to look OK.

[carusoam]

In the polymer world...

That would not be normal...

Random swelling caused by a seal absorbing a solvent is going to have difficulty being a seal... over time..

The polymer world would have a specification for swelling in various solvents... given in %... numbers smaller than 1% would be normal....
 

Seeing the results of a couple messed up seals around here is not a comforting feeling...

 

A similar situation in the Mooney world...

Somebody used the wrong O-rings in my fuel caps.... they extended in diameter, and didn’t fit properly... they failed by letting water into the tank...

 

Continue to keep both eyes open...

The pics of the other seal around here continued to expand over time...

Expect the seal will be maintained as it is confined in place... where it is not confined it may expand a lot... it may be possible it sheds parts...

 

Got any small bits to trim off and leave in 100LL?   If a small hair continues to grow into a big worm.... you will want to find a better seal...

Did we ask @OSUAV8TER our resident rubber seal provider, if he has seen a similar seal made from better materials..?

Interesting additional detail about the change in the wall diameter... the more the seal gets compressed, the tighter it will seal in the tighter area...
 

researching the web... I found a couple of fuel strainer companies with various Orings... none of them were specific about the material being used for their rubber oring...  bummer...

Not an alarmist, just sharing some discomfort... 

PP thoughts only, not a mechanic either....

Best regards,

-a-

[Vance Harral]

Thanks for your thoughts, Anthony.  I'm with you - not feeling alarmist about it at the moment, but I'd be a lot more comfortable if the gasket hadn't changed dimensions after soaking in 100LL.  Note that this wasn't exactly what I'd call a controlled study: I didn't note temperature, atmospheric pressure, humidity etc. before and after.  We also didn't let the gasket sit out of the fuel for another several days to see if it returned to the original dimensions.  It did weigh the same, but again, my scale isn't sensitive enough to show small variations.

Mostly what I wanted to check for was any evidence of the material breaking down, and there was none of that.  The preceding gasket was either cut before/during installation, or deteriorated very rapidly.  Given what it looks like, the former seems more likely, but who knows?  I can't cut a sample from the gasket to monitor without destroying it.  We could buy another one and continue to monitor it, but that would be a different part, and it already appears there is variation between parts/lots.  At some point, all you can do is verify it's not leaking on preflight, and go fly it.  Barring some new development, we hope to do that this week.  Coming up on 3 months now since the airplane last flew.

Edited May 26, 2020 by Vance Harral

[MB65E]

Brown aircraft can cut you exactly what you need out of better rubber. I’ve been really happy with them. I’ve had mine apart a few times and the brown gasket was reused with our issue. 
Sorry for your troubles.
-Matt
 

[Vance Harral]

The airplane was test flown today and nothing blew up.  So far, so good.   Still watching it like a hawk on a daily basis for evidence of leaks, though.

[Vance Harral]

This'll be my last post to this thread unless something else interesting happens.  Two weeks of calendar time and 6 hours of flight time on the airplane since the last gasket was installed, with no issues.  I think the problems are all licked, but will stay vigilant.

[carusoam]

Nice follow up, Vance!

Best regards,

-a-

[Browncbr1]

On 6/8/2020 at 4:57 PM, Vance Harral said:

This'll be my last post to this thread unless something else interesting happens.  Two weeks of calendar time and 6 hours of flight time on the airplane since the last gasket was installed, with no issues.  I think the problems are all licked, but will stay vigilant.

it sounds like this seal worked out...   i saw some dimensions you gave, but couldn't find any part numbers on sky geek or spruce.   I'm trying to source all o-rings and seals to overhaul my fuel selector.  are you able to point me to your source for this seal?    thanks, craig

[Vance Harral]

No problems with fuel leaks since the last update.  The airplane went through another annual inspection this spring, and that seal looked OK, so we just re-used it.  I'm wary of using replacement seals at this point, so we're going to use the existing one until/unless it fails a visual inspection.

The seal in question is Mooney P/N 940057-001, LASAR lists it as their P/O #18172.  It's not a "standard" part, you can't order it from Sky Geek or Spruce.  These gaskets are produced by Mooney, and you have to order them through an MSC.  They are of course ridiculously overpriced, I paid $44.21 when I ordered one in February 2020.   I'm sure there are Mooneys out there with Duke's fuel selectors, which are flying with a black or grey-market version of this seal, that was just cut from a spare sheet of rubber.  I'm even sympathetic to that, given our recent experience with the "factory approved" part.  But if you want the official part, you have to order it from Mooney, through an MSC.

[cferr59]

You can also order the gasket from Brown Aircraft.  The part number is GL-30-HD, but you need to call them and ask them to make it 1/16" thick.