G100UL thread MIA?

[Igor_U]

15 minutes ago, GeeBee said:

With regard to applying sealant before assembly and riveting Mooney did that in later models then abandoned the method. As it was explained to me by WetWingolists, to do this assembly method requires precision riveting. This is because simply "gooping" the pieces and riveting results in the sealant being pushed out or being too thin. There has to be a precise gap for the sealant to reside within. Simply put, the Mooney factory did not have such precision equipment nor was it economical to purchase such equipment so they returned to the old method. I am told they paid for a lot of reseals using the old method on these aircraft.

Not really true. There shouldn't be a precise gap on sheet metal parts, mechanic would normally apply the sealant on the surfaces (rib flanges, skins, etc) and wet rivet it during the installation. The squeezed out sealant is (while is still "wet") allowed to be formed to the fillet seal or/and additional sealant can be applied for that. It is normally a manual process with no specially equipment.  

All major OEMs (BIG and small) are doing it this way and I saw it numerous times, so why Mooney wouldn't be able to do so is beyond me...  

[GeeBee]

5 minutes ago, Igor_U said:

Not really true. There shouldn't be a precise gap on sheet metal parts, mechanic would normally apply the sealant on the surfaces (rib flanges, skins, etc) and wet rivet it during the installation. The squeezed out sealant is (while is still "wet") allowed to be formed to the fillet seal or/and additional sealant can be applied for that. It is normally a manual process with no specially equipment.  

All major OEMs (BIG and small) are doing it this way and I saw it numerous times, so why Mooney wouldn't be able to do so is beyond me...  

All I can do is report to you what the top people in the tank sealing business reported to me. 

[KSMooniac]

8 minutes ago, Igor_U said:

Not really true. There shouldn't be a precise gap on sheet metal parts, mechanic would normally apply the sealant on the surfaces (rib flanges, skins, etc) and wet rivet it during the installation. The squeezed out sealant is (while is still "wet") allowed to be formed to the fillet seal or/and additional sealant can be applied for that. It is normally a manual process with no specially equipment.  

All major OEMs (BIG and small) are doing it this way and I saw it numerous times, so why Mooney wouldn't be able to do so is beyond me...  

I disagree, Igor.  We're currently designing 0.005" gaps for fay sealant on the civilian and defense programs I've worked in the last many years (bigger vehicles than our Mooneys!).  None of these are sheet metal, though, which would be more forgiving but less precise.  I doubt 0.01" of thickness variation would matter much on a wing profile at our scale, though.  

I do wish Mooney had applied fay sealant and wet-installed the rivets, plus fillet sealing and brush coating sealant over all of that.  

[Igor_U]

1 minute ago, KSMooniac said:

I disagree, Igor.  We're currently designing 0.005" gaps for fay sealant on the civilian and defense programs I've worked in the last many years (bigger vehicles than our Mooneys!).  None of these are sheet metal, though, which would be more forgiving but less precise.  I doubt 0.01" of thickness variation would matter much on a wing profile at our scale, though.  

I do wish Mooney had applied fay sealant and wet-installed the rivets, plus fillet sealing and brush coating sealant over all of that.  

Scott,

Very true but all modern designs are these days machined with specified tolerances of +.005" (or so) but in realty accuracy if the machined surface is even better. Sheet metal parts, even today, are typically +/.030" and would have a "pull-up" when riveted during the assembly. I would never use a design gap for that wing and as you know, I do that for living. 

There's no doubt that fabrication of the wing with not faying surface seal or wet riveting was cheaper but ultimately cost owners more in maintenance effort and sealing the tanks eventually needs to be done from the scratch. Unfortunate!

On the other hand, I bet no one at Mooney expected that my plane would be flying almost 60 since the first flight so there's that. 

[hubcap]

If I understand correctly, and I may not, but didn’t all of the suspect fuel come from the same FBO? 

If that’s the case, is it possible that the fuel was contaminated only at that location with a product that could cause paint to peel?

[gabez]

18 minutes ago, hubcap said:

If I understand correctly, and I may not, but didn’t all of the suspect fuel come from the same FBO? 

If that’s the case, is it possible that the fuel was contaminated only at that location with a product that could cause paint to peel?

all fuel was purchased at KWVI. 

[IvanP]

9 minutes ago, gabez said:

all fuel was purchased at KWVI. 

May be worth obtaining a sample directly from the pump and get analyzed by couple of different labs. However, the questions is how would some mysterious compounds find their way to the fuel truck or storage tank?  

[varlajo]

In addition to leaks and seeps through imperfects seals and rivets, I am also concerned about the fuel that slowly vents with expansion in summer. Those slow leaks last for hours and are impossible to control for - other than to always park the plane with less than 80% full tanks. The recommendation to "immediately" clean spills after fueling would be impossible to follow in the above scenario. 

[gabez]

12 minutes ago, IvanP said:

May be worth obtaining a sample directly from the pump and get analyzed by couple of different labs. However, the questions is how would some mysterious compounds find their way to the fuel truck or storage tank?  

that fuel is probably gone. but I have about 70 gallons in my plane

[FlyingDude]

I'm monitoring Pb-free avgas developments closely, too.  One thing: though toulene is the used in the CS3204 polysulfide sealant, and in theory it is supposed to soften the sealant, my experience during the resealing of my tanks was otherwise.  I couldn't soften the old sealant with copious amounts of toulene, so I resorted to acetone & MEK.  I wonder how much toulene in the gas actually softens the sealant, if it indeed softens the sealant.

Maybe we'll all just have to beef up the top coat.  I'd prefer that over mandatory bladder installations.

[Pinecone]

On 12/18/2024 at 12:30 PM, IvanP said:

Nothing is perfect, including the free market competition. The VHS v. BetaMax battle was decided by marketing strategies and not by a government mandate, though. I cannot judge which of the two techmologies you mentionwed was better, but I am willing to bet that neither forced their respective users to pay tens of thousands of dollars in repairs. Contrast that with madating a fleet-wide use of fuel that could potentially adversely affect airworthiness of many aricraft without having sufficient data.

Again., I am not saying that G100UL is causing the problems described by some users, but I woud like to see some transparency about the testing process and results. Maybe the FAA has the data, maybe GAMI had tests done by independent agent. Transparency will help to address the concerns. I agree that it woudl be impractical to have two piston fuels.

Your point about price is valid. If most pilots do make their decision based only on price as you aserted, we can test this theory by making UL fuel cheaper than LL and see how it goes  . I sincerely believe that UL fuels should and will be the future, I just do not want to have this to cause problems for us by mandating something that has not been sufficiently tested and proven safe.    

GAMI is not forcing anyone to use their fuel.  You have a choice.  Once 100LL is banned, you can use G100UL or any other fuel that is allowed by your TDCS as amended by STC.

GAMI has just given us an answer to how to fly once 100LL is banned.  And it WILL be banned.

You are free to come out with your own version of UL AVGAS.

[Pinecone]

On 12/18/2024 at 1:20 PM, MikeOH said:

I don't know about other posters, but that is the 'mandate' I'm referring to.  I believe the term used is 'commercially available' which is rather undefined.  The concern is that other airports may now view G100UL as 'commercially available' and be pressured by that environmental agreement/ruling to stop selling 100LL.  Not sure how it will play out.

Go over to Beech Talk.  Scott Dyer did a good lay person explanation of the Consent Decree.  "Commercially Available" IS defined in the Consent Decree.

And the Consent Decree was agreed to by the FBOs and fuel suppliers.  They were not directly forced to agree.  

[IvanP]

2 hours ago, Pinecone said:

GAMI is not forcing anyone to use their fuel.  You have a choice.  Once 100LL is banned, you can use G100UL or any other fuel that is allowed by your TDCS as amended by STC.

GAMI has just given us an answer to how to fly once 100LL is banned.  And it WILL be banned.

You are free to come out with your own version of UL AVGAS.

You are absolutely right - GAMI is not forcing anyone to do anyting. It is the government that is forcig us to use UL fuel. 

While we may have a choice for now not to use it, that choice is going away soon. I have no issue with using UL fuel, GAMI or otherwise, just want it not to damage my plane. 

[Marc_B]

Most threads discussing unleaded fuel seem polar.  Either you are a fan of all things unleaded, or you're against change.  The problem is that currently there isn't an organization that has taken ownership for responsible transition to unleaded fuel, monitoring adverse events and collecting data for implementation and outcome.  This is where I've always hoped that a partnership with AOPA and the FAA would step in.

Blanket praise isn't any more helpful than blanket condemnation.  I'd rather discuss what issues have been seen and how to mitigate them in a rational way.  You're not going to hear much detrimental information from GAMI and no one should expect to.  They're selling a product that has to reach an inflection point to make it to the transition to be the only 100UL fuel out there when 100LL is removed legislatively.  Unfortunately in current state, most FBOs are unlikely to carry a variety of fuels...perhaps phase "2" after transition will be to explore options for multiple fuel availability?  After all, we see diesel, E85, 85/87/91 and sometimes even ethanol free fuels all regularly at the pump.

We need to openly and rationally discuss issues that are being seen with any new fuel so that we can better understand how to mitigate risk and continue to fly safely.

Sounds like G100UL uses increased amounts of xylene instead of lead for octane.  My guess is that the overall aromatic content of G100UL is higher than 100LL.  There's also other compounds that may result in paint staining if not promptly removed and cleaned.  Also due to the higher xylene content it produces more black soot as the aromatics produce soot when burned, moreso when flown rich.  G100UL has been tested to mix with 100LL, but no other mix testing has been publicly released.

It is interesting that when the G100UL STC was applied universally, this was more directed at the engines than the airframes.  I'm sure that extensive testing was done on an engine stand in product development, but that doesn't equate to the beta testing that will result with the early adopters in a wide range of aircraft.  We'll start to see more real world data that (by the nature of live testing) has plenty of confounders (i.e. no one has perfect paint, and very few will have perfect sealant, etc.).  But that doesn't mean we just blankly magnify or minimize the issues seen. 

The problem is that it's turned into being "up to us" to read and understand this, and with the limited data each of us have, that puts us more in a position of speculation than fact.  So we all make our own decision to what appears to be the "best" option.  Many times this becomes more of an emotional decision than a rational one.

At the end of the day, lots of aircraft have old paint, old engines, old sealant, old components, because new piston aircraft production/purchase is low.  So what do we need to do with our aircraft in preparation for use of alternative fuel?  If we have aircraft without hardened valve seats, are there fuels that won't work?  Are there certain components, seals, hoses, sealant, etc that aren't compatible with alternative fuels?  Should this escalate our need to reseal a minor leaking wet wing?

Yes, the aviation industry is moving away from lead.  Yes, there is a large political and fear based aspect to this (you're poisoning our children).  Yes, there are changes that will have to be made and challenges for all involved from producer to consumer.  But this is the way aviation fuel is moving regardless of whether we move with it and even despite efforts to move against it.

But at the end of the day, the most important part is that we keep the fleet, the public and ourselves safe.  So lets discuss the details so that we all can be better educated, more knowledgeable pilots.

MODERATOR:  What about a forum for Alternative Fuel Discussion and move all threads about alternative fuels there?  It'd be nice to see real world data for changes in fuel consumption, changes in engine monitor data, problems seen, pictures of before/after borescope/fuel leaks/etc.

[toto]

5 minutes ago, Marc_B said:

MODERATOR:  What about a forum for Alternative Fuel Discussion and move all threads about alternative fuels there?  It'd be nice to see real world data for changes in fuel consumption, changes in engine monitor data, problems seen, pictures of before/after borescope/fuel leaks/etc.

You might dual-post this suggestion over on the suggestions forum. I don’t think there is a MS moderator per se, but Craig will see the suggestion there. 

https://mooneyspace.com/forum/9-bug-reports-suggestions/

[MikeOH]

6 hours ago, Pinecone said:

Go over to Beech Talk.  Scott Dyer did a good lay person explanation of the Consent Decree.  "Commercially Available" IS defined in the Consent Decree.

And the Consent Decree was agreed to by the FBOs and fuel suppliers.  They were not directly forced to agree.  

I did not see any mention of cost/pricing in the Consent Decree. Please point it out because calling something "Commercially Available" without consideration of commercial cost comparison is pretty oxymoronic!  How about $200 per gallon?  That's certainly "Commercially Available"

Oh, yeah, I'm sure the FBOs/suppliers weren't subject to any coercion before signing.  Kind of like your constant reminder that no one will force anyone to buy G100UL in the future because we're all free to produce our own avgas if there is no other choice available!

[GeeBee]

Just because you see no wall does not mean there is no writing.

 

[George Braly]

17 hours ago, MikeOH said:

I did not see any mention of cost/pricing in the Consent Decree. Please point it out because calling something "Commercially Available" without consideration of commercial cost comparison is pretty oxymoronic!  How about $200 per gallon?  That's certainly "Commercially Available"

Oh, yeah, I'm sure the FBOs/suppliers weren't subject to any coercion before signing.  Kind of like your constant reminder that no one will force anyone to buy G100UL in the future because we're all free to produce our own avgas if there is no other choice available!

You might re-read the consent decree.   There are provisions there that would exclude $200/'gallon fuel from the concept of "commercially available." 

Everyone should understand - - the issue before the Court in California is the enforcement of a civil contract.  

This contract was adopted by the Court as part of a consent decree.  The issue before the Court is whether or not the distributors (NOT the FBOs - - at least not yet, at this time) violated their formal agreement. 

 

[redbaron1982]

38 minutes ago, George Braly said:

You might re-read the consent decree.   There are provisions there that would exclude $200/'gallon fuel from the concept of "commercially available." 

Everyone should understand - - the issue before the Court in California is the enforcement of a civil contract.  

This contract was adopted by the Court as part of a consent decree.  The issue before the Court is whether or not the distributors (NOT the FBOs - - at least not yet, at this time) violated their formal agreement. 

 

All this sounds like a communist country (or at least state). Forcing a market to switch to a monopoly is the perfect recipe for corruption, abuse, and kill competition. 

Lucky for us, it looks like Swift 100R might be relatively close (2025?) to be an alternative, with ASTM cert. Maybe G100UL is just a bleep in the transition to unleaded fuel. 

[Pinecone]

17 minutes ago, redbaron1982 said:

Lucky for us, it looks like Swift 100R might be relatively close (2025?) to be an alternative, with ASTM cert. Maybe G100UL is just a bleep in the transition to unleaded fuel. 

ASTM does not certify anything.  They write consensus standards.  That is a group of people agree that there should be a standard for something and that this is what that standard is.  It guarantees nothing.

Also, many TDCS specify fuels meeting D910, which no unleaded fuel can meet, as it requires lead in the fuel.  So those aircraft will need an STC. 

[redbaron1982]

7 minutes ago, Pinecone said:

ASTM does not certify anything.  They write consensus standards.  That is a group of people agree that there should be a standard for something and that this is what that standard is.  It guarantees nothing.

Also, many TDCS specify fuels meeting D910, which no unleaded fuel can meet, as it requires lead in the fuel.  So those aircraft will need an STC. 

As long as we are not forced to use paint stripper as fuel ...

[gabez]

1 minute ago, redbaron1982 said:

As long as we are not forced to use paint stripper as fuel ...

definitely the paperwork that came with the STC was not comprehensive in describing how aggressive the fuel is towards paint. This is not normal good or bad paint, new or old. still waiting on my mechanic to see if this is limited to the co-main or all 4 tanks. 

[dkkim73]

29 minutes ago, redbaron1982 said:

As long as we are not forced to use paint stripper as fuel ...

"It's a floor wax *and* a dessert topping!" -old SNL skit

[EricJ]

25 minutes ago, Pinecone said:

ASTM does not certify anything.  They write consensus standards.  That is a group of people agree that there should be a standard for something and that this is what that standard is.  It guarantees nothing.

Many people don't understand how standards work, and since many work a little differently than others, that's sometimes understandable.   Some standards have certification and verification bodies that serve to assure that products meet the standard.   Examples of this are WiFi and Bluetooth, which are really industry consortia or alliances that serve only to certify that products meet relevant standards, in the case of WiFi and Bluetooth the standards are IEEE 802.11 and 802.15.   If a product pays for certification and testing by the relevant certification body indicates it meets the standard, then the product can display the WiFi or BT logo indicating compliance.    Since the logos are trademarked there is an enforcement path against counterfeits.  The WiFi Alliance owns the trademark on the WiFi logo, and the Bluetooth Special Interest Group owns the trademark for the BT logo.    USB is similar but the USB Implementer's Forum does both functions of writing the standard and certifying testing to the standard.    The IEC has adopted USB-C as its own standard, which also happens from time to time.   I think they still rely on USB-IF for certification, though, since they own the trademarks.

ASTM and things like MS standards are a little different in that there is no "marking" consortium that has enforcement powers via marking or other means.  Most such standards specify test methods that verify compliance, and ASTM uses this method, i.e., specific tests are defined which indicate compliance (or not) to the relevant standard.   Interested parties, like distributors, can ask suppliers for "certification" that a product has been tested and show compliance to the standard via the tests.   Sometimes in these case it is up to the interested party whether self-certification by a vendor is adequate or third-party testing should be done, but in any case there should be a documentation trail showing that the tests were performed according to the standard and the results meet the criteria for compliance.

For things like fuels, lubricants, MS hardware, etc., certification and verification is almost always done behind the scenes in the manufacturing or distribution stages where it is invisible to the consumer.   Rest assured, though, if there is money and potential liability involved, there will be a thorough verification trail that has been insisted on by some player(s) in the supply chain and/or their insurers.   The various government agencies involved, like the FAA, NTSB, DOT, FDA, etc., often take it seriously when there appears to be counterfeiting happening, so they're often the enforcement agencies for such standards.   If these agencies are signficantly cut or understaffed, one consequence may be an increase in counterfeiting, which has happened before in history.

I worked in standards for a good part of my career, specifically IEEE 802.11, 802.16, and 3GPP, and was involved in many others in ITU, Intelsat, etc.   Compliance verification and enforcement are necessary pieces of any standard, or it is essentially useless as a standard.   Standards like ASTM are usually enforced by whoever it is that requires them, e.g., a government agency that specifies a fuel must comply, then also enforces that compliance.

[Marc_B]

The Type Certificate for my aircraft says: "100LL or 100/130 octane minimum grade aviation gasoline".  100LL is actually a 100/130 fuel.  The ASTM D910.(year) just is a fuel specification so that when a distributor receives a batch of fuel it has been certified and tested to conform to a standard.  This standard does allow variations in content and so some fuel may have different amounts of components...but it conforms to the ASTM D910 standard for leaded aviation fuel.

ASTM in the way we use it is a quality assurance standard.  They have specs and testing procedures that insure that the fuel conforms to a standard anywhere you purchase it.  The FAA sets the standard...ASTM just insures that the standard is met.

I don't care where or how my fuel is certified, but I very much care that the fuel I purchase meets a standard.  I wouldn't want hot rod joe mixing up my 100UL and my FBO passing it off as AVGAS.