Fuel tank reseal

[Lancer11A]

What was the issue?

[gsxrpilot]

2 hours ago, Lancer11A said:

What was the issue?

You uploaded the pictures as files instead of just attaching the pictures to the post. No one wants to have to go download files just to see the pictures.

[cliffy]

2 hours ago, Lancer11A said:

What was the issue?

Some people can't open that type of file

[47U]

I got them out of order... and not guaranteeing orientation... (two edits later...)

 

 

 

 

 

 

 

 

[Mufflerbearing]

Keep the photos coming with your progress.  I'm toying with the idea of doing this with my IA. 

 

[Sandman993]

At least no one will steal your ship right now.

[Vance Harral]

On 1/27/2021 at 11:43 AM, RobertGary1 said:

I’m also unconvinced about the hard landing theory

Me too, primarily because flying in anything other than glass smooth air generates a ton of flex cycles on the wing, some of which are on par with the loads of a hard landing.  If rough landings impact sealant life, then so does turbulence.

[kortopates]

21 hours ago, Vance Harral said:

Me too, primarily because flying in anything other than glass smooth air generates a ton of flex cycles on the wing, some of which are on par with the loads of a hard landing.  If rough landings impact sealant life, then so does turbulence.

Why then did Cessna Cardinals wings, with the same integral sealed tanks as ours, and mostly built back in 70's, only recently a few are beginning to need resealing - very much unlike our Mooney's? 

[0TreeLemur]

20 minutes ago, kortopates said:

Why then did Cessna Cardinals wings, with the same integral sealed tanks as ours, and mostly built back in 70's, only recently a few are beginning to need resealing - very much unlike our Mooney's? 

Perhaps differences in the stress distribution in the main spar, especially the occasional hard landing?   With the Mooney landing gear directly connected to the wing plus the use of rubber pucks for shocks, there is probably more abrupt deflection that might cause sealant to locally debond from the aluminum.  Plus, in the case of the C wing landings stresses are reduced by the landing gear "springiness".  This almost certainly means that M wings experience a lot more shock loading than C wings.

Just a WAG, not an aeronautical/structural engineer.

[Vance Harral]

36 minutes ago, kortopates said:

Why then did Cessna Cardinals wings, with the same integral sealed tanks as ours, and mostly built back in 70's, only recently a few are beginning to need resealing - very much unlike our Mooney's? 

I was not aware Cessna Cardinals had wet wings with a substantially better service record than Mooneys.  If true, that is certainly interesting data.  Did Cessna use the same type of sealant in the 70s as Mooney?  If not, then whatever they used is likely superior.  If so, then yeah, the initial difference would seem to be the more direct coupling between the wings and the landing gear causing additional flex during ground ops.

It's worth noting that there are a lot more Mooneys than Cessna Cardinals, and that may have something to do with the data too.  But Wikipedia says 4295 Cardinals were built from 1968-78, so that's certainly plenty of data points.

It's always been my understanding that sealant breakdowns and accompanying patch/reseal work with age are simply a fact of life in wet wing airplanes, be they Mooney, RV, Boeing, whatever.  Say, 8-10 year life is pretty reasonable, 20-30 is quite good, and the conventional wisdom is that nothing goes longer than that.  So the idea that most Cessna Cardinals have gone 40-50 years with no wet wing maintenance seems extraordinary, and worth a polite challenge.  When I tried to look for information about this just now, what mostly turned up were comments about how the very few tank access panels in the Cardinal make tank reseals so extraordinarily difficult that nobody wants to do them, e.g. https://www.pilotsofamerica.com/community/threads/cessna-177-b.100637/.  And here's a story of Cardinal wet-wing patches that went so badly that it led to a wing replacement: https://www.tennesseeaircraft.net/2017/11/15/when-more-is-less/ (scroll down to "Cardinal Fuel Tank Repair"). These are just anecdotes, but I'm good-naturedly skeptical of the claim that Cardinals have a much better wet-wing longevity record than Mooneys (or anything else).

[EricJ]

1 hour ago, kortopates said:

Why then did Cessna Cardinals wings, with the same integral sealed tanks as ours, and mostly built back in 70's, only recently a few are beginning to need resealing - very much unlike our Mooney's? 

Cessna spring-steel landing gear is an awful lot more compliant than Mooney pucks.   Just an observation.   There may be other factors.

[kortopates]

1 hour ago, Vance Harral said:

I was not aware Cessna Cardinals had wet wings with a substantially better service record than Mooneys.  If true, that is certainly interesting data.  Did Cessna use the same type of sealant in the 70s as Mooney?  If not, then whatever they used is likely superior.  If so, then yeah, the initial difference would seem to be the more direct coupling between the wings and the landing gear causing additional flex during ground ops.

It's worth noting that there are a lot more Mooneys than Cessna Cardinals, and that may have something to do with the data too.  But Wikipedia says 4295 Cardinals were built from 1968-78, so that's certainly plenty of data points.

It's always been my understanding that sealant breakdowns and accompanying patch/reseal work with age are simply a fact of life in wet wing airplanes, be they Mooney, RV, Boeing, whatever.  Say, 8-10 year life is pretty reasonable, 20-30 is quite good, and the conventional wisdom is that nothing goes longer than that.  So the idea that most Cessna Cardinals have gone 40-50 years with no wet wing maintenance seems extraordinary, and worth a polite challenge.  When I tried to look for information about this just now, what mostly turned up were comments about how the very few tank access panels in the Cardinal make tank reseals so extraordinarily difficult that nobody wants to do them, e.g. https://www.pilotsofamerica.com/community/threads/cessna-177-b.100637/.  And here's a story of Cardinal wet-wing patches that went so badly that it led to a wing replacement: https://www.tennesseeaircraft.net/2017/11/15/when-more-is-less/ (scroll down to "Cardinal Fuel Tank Repair"). These are just anecdotes, but I'm good-naturedly skeptical of the claim that Cardinals have a much better wet-wing longevity record than Mooneys (or anything else).

Paul New, the Tennessee Aircarft owner, is one of my colleagues at Savvy. They replaced the wing for several reasons, foremost because a skin had been improperly replaced. But note too how the salavge wing from the same era tested leak free. Another one of my colleagues at Savvy is a Cardinal RG owner active with the Cardinal users group - where I was first schooled on this topic. But no doubt access is very difficult to reseal a Cardinal wing but they also don't have the needed specialist to do reseals like we have all the Mooney specialist with 5-6 shops across the country who specialzie in reseals - nobody wanted to do a reseal 20 years ago either except for Edison. I think for the most part, the rare leak in a Cardinal is still mostly just being patched rather than resealed. You'll  hear folks says all Mooney's leak some, which is an exageratopn, and although there are lots of leaking Mooney's I have yet to see a Cardinal leak yet, although I've heard it does happen and I certainly haven't seen the same number of Cardinals. Unfortunately the Mooneyspace for the Cardinals requires paid access at https://www.cardinalflyers.com/

The main big difference is that Cardinal's landing gear is both more springy,  without pucks that get hard, but all load transfers is to the fuselage rather than the wing. It probably doesn't help either that the gear is right in the middle of the tank versus normal in flight wing flex is across the entire wing length.

Edited February 10, 2021 by kortopates

[Vance Harral]

Thanks for the follow-up, @kortopates.  I'm still not entirely convinced the smoothness of landings and/or condition of pucks in Mooneys plays a significant role in sealant lifetime, but the comparison with the Cardinal is worth considering. 

[MikeOH]

We perform BOTH shock and vibration testing of our electronic assemblies at my company.  There is a big difference in each one's effects on the hardware.  You can pass vibe and fail shock.  Granted electronic assemblies are NOT airplane wings, but I think the principle still applies.

To me, in flight turbulence is much more akin to vibration than shock, although I admit to having a few "shock" type hits in rough air!  Either way, the nature of turbulence is going to spread its effects across the entire wing whereas the landing shock load on a Mooney wing is applied in a localized area through a compression spring (the donuts) which absorb some of the shock (reduce transmitted 'g'), UNLESS they are as hard as a rock. So, it makes sense that donut condition and smoothness of landing directly affect the stress the tanks are subjected to.

Not so with the Cardinal where the gear is NOT bolted to the wing and, I suspect, has much more compliance than our donuts.

All, IMHO, of course

[Will.iam]

Maybe the fact that the cessna needs so much more gas to go anywhere their planes sit with tanks that are more full than the mooney thus helping in heat sink to keep the temps lower when out in the sun.  

[carusoam]

Many of the sealant problems we see...

Are often chemistry related, and the environment it lives in...

Some sealant has fallen off the tank walls...

If the Cardinal guys aren’t suffering from that... they got better sealant... or prepped their surfaces differently...

 

For anyone saying all Mooneys leak...  Long bodies were a changing of the guard... when it comes to the sealing methodology...

The sealant stays in place very well too...

They also live indoors, mostly...

26 years... the only resealing done on my O was during the PPI... at least one top inspection panel needed some attention... all of them that got resealed at the same time...

PP thoughts only, not a mechanic or chemist...

Best regards,

-a-

[cliffy]

Yes our wing is stiff but only to a point

Think of the pressure point from the landing gear and the "flexing" that the spar will go through as you impact the runway.

The gear is at the outboard end of the tank right on the back wall of the tank. The wingtips bend down inertia while inboard of the gear point tries to go up. You also get the spar between the main wheels trying to fold up from the pressure at the same time.

If the sealant is old and dry it can't flex as much as it used to.

The Cessna doesn't have the same dynamics with the pressure point and it has a much longer force absorption time frame due to the longer flex time of its gear to absorb the landing impact.   

Feel how hard old Mooney pucks are compared to new ones. Rubber gets hard with age and doesn't absorb impact near as well  the older it get. 

 

[Mooney-Shiner]

On 2/8/2021 at 2:14 PM, 47U said:

I got them out of order... and not guaranteeing orientation... (two edits later...)

 

 

 

 

 

 

 

 

Great work! I just did some patching and it is really tedious. 

But I used the shop-vac to the air-vent to find leaks. Its pretty cool idea with 12V pump! Just make sure that the vacuum is not too strong and it will not collapse the sealant.  

[Lancer11A]

Down to extracting the original sealant. Light tan in the photos.  Every nook and cranny.  Due to work and weather will have to take week away from the project.  But it's going better than I expected.  The goodness is my IA has done this on a few Mooneys.  Knowledge is key to this success .  Just like building a home, the foundation has to be correct and true.2E7EC4AF-8EF4-45CD-AAE0-D461C413A7BB.heic

7CA54AD4-9FC1-4036-BB42-1BFD365EF34C.heic 988B7D88-D059-4031-802B-E771484CE521.heic 3AAB2C6B-5ADF-449A-AF4A-6CA6578075E2.heic

[carusoam]

Lancer,

There is a better way to show pics...

Click: Choose files, photo library...

Best regards,

-a-

[affricate]

I flew my Bravo from Tucson to Ft Lauderdale, Edison did a great job. Made it in 8 hrs!

[carusoam]

Go Bravo!

Got any pics?

-a-

 

[affricate]

46 minutes ago, carusoam said:

Go Bravo!

Got any pics?

-a-

 

[carusoam]

Palm trees are nice this time of year.... from here. 

-a-

[affricate]

4 minutes ago, carusoam said:

Palm trees are nice this time of year.... from here. 

-a-

I bet y'all cold up in NJ!  We got those palms down in Tucson, just no H2O