G100UL - fuel leak

[Marc_B]

43 minutes ago, A64Pilot said:

From my understanding this fuel requires no aircraft modifications, is a simple drop in, is completely miscible with other existing fuels, so why does it require an STC?

I gather its because fuel is actually listed on the type certificate.  So a change in fuel would require an amendment.  But what I can't find is when did the listing of "100LL or 100/130 octane minimum grade aviation gasoline" turn into ASTM D910?  (certainly understand ASTM D910 is 100LL).  G100UL meets the 100/130 minimum octane and according to Mr. Braly is completely fungible with 100LL.  But I guess that "100/130..." isn't referring to a spec but rather speaking about GREEN avgas that had a higher lead content than 100LL?

So I'm not sure why the FAA can't just list G100UL as a "100/130 mimimum grade aviation gasoline" and be done with it.

 

The follow up question, is if another producer came up with an unleaded fuel though PAFI/EAGLE with an ASTM spec, what would the FAA have to do to make this usable in our aircraft??  Would they then supply an STC to that manufacturer and the costs associated would just be rolled into the fuel?  Because NO unleaded fuel is going to meet the ASTM D910 spec as it has LEAD in the spec.

[EricJ]

9 hours ago, Marc_B said:

https://www.sciencedirect.com/science/article/abs/pii/S0016236120319244
 

Decent overview  of 100 unleaded fuel. Also points out a couple of the hurdles with various methods to develop 100/130 fuel without lead. 

That's pretty cool, and shows how much work is going on and has been going on globally.    We'll get 100UL, I don't see a need to rush.    The CA issue is politically solvable, but whether it will be or not remains to be seen.

[Ibra]

1 hour ago, Marc_B said:

But what I can't find is when did the listing of "100LL or 100/130 octane minimum grade aviation gasoline" turn into ASTM D910? 

So I'm not sure why the FAA can't just list G100UL as a "100/130 mimimum grade aviation gasoline" and be done with it.

For 1st question, I think somewhere mid-1980 where engine manufacturers forced an extra wording to airframe TCDS (now they reference to SI1070 which reference ASTM approved fuels). You could argue that older aircraft can use any octane rating as long as that's what is stated fot airframe approval (even in cases where it's not recomanded or approved by engine manufacturers).

If fuel is approved for engine, it should be easy to get blanket FAA airframe approval (to give an example: in EASA land, we can use UL fuels approved by engine manufacturers without airframe STC as "minor modification": logbook signature. For example, Total UL91 or Hjelmeco 91/96).

For 2nd question, I assumed that because G100UL is not approved for engine by Lycoming or Conti, it has to get FAA airframe approval via STC? 

 

Edited December 23, 2024 by Ibra

[EricJ]

1 hour ago, Marc_B said:

I gather its because fuel is actually listed on the type certificate.  So a change in fuel would require an amendment.  But what I can't find is when did the listing of "100LL or 100/130 octane minimum grade aviation gasoline" turn into ASTM D910?  (certainly understand ASTM D910 is 100LL).  G100UL meets the 100/130 minimum octane and according to Mr. Braly is completely fungible with 100LL.  But I guess that "100/130..." isn't referring to a spec but rather speaking about GREEN avgas that had a higher lead content than 100LL?

There are many other fuel specs besides ASTM, and in other parts of the world use other specs (the A in ASTM is American).   So ASTM isn't specified because other compliant "grades" can be used, especially in other parts of the world.  For Lycoming engines SI1070 lists specific standards associated with the various "grades".

For a consumer, if you pull up to a tank that says something like "grade 100 Aviation Fuel" on it or something similar, I don't think there's anything stopping you from putting that in your airplane, since it reflects what it asked for in the aircraft TCDS. 

1 hour ago, Marc_B said:

So I'm not sure why the FAA can't just list G100UL as a "100/130 mimimum grade aviation gasoline" and be done with it.

I think they could ultimately do that for whatever fuels wind up being in common use.   "Acceptable to the administrator" is the catch-all phrase that makes pretty much anything approved, so if an official administrative action says "You can use X as an approved fuel in place of Y", or "fuel X is approved as a grade 100 fuel", then I'd think that's pretty much done.   I'm sure there are administrative hurdles to do that, but we're told government is going to be much more "efficient" in the coming years. 

1 hour ago, Marc_B said:

 

The follow up question, is if another producer came up with an unleaded fuel though PAFI/EAGLE with an ASTM spec, what would the FAA have to do to make this usable in our aircraft??  Would they then supply an STC to that manufacturer and the costs associated would just be rolled into the fuel?  Because NO unleaded fuel is going to meet the ASTM D910 spec as it has LEAD in the spec.

ASTM D910 has a maximum amount of lead allowed, but there is no minimum.   Regardless, there seems to be consensus, including the paper you posted previously, that the details of D910 are difficult or impossible to meet without lead.   Fortunately there are ASTM specs being developed for the new case.

[Ibra]

13 minutes ago, EricJ said:

I think they could ultimately do that for whatever fuels wind up being in common use

My feeling they can and will but it has to be a fuel that is "blessed" by Lycoming and Continental

For example, Swift UL94 is presented as 100LL without TEL, however, it has some additional aromatics that Lycoming does not like ==> Swift STC 

I have not figure out what it takes to fly using Total UL91 in US aircraft: it's listed in Lycoming SI.1070, it fits ASTM D7547 for unleaded fuels. Can I use it in N-tail PA28? or it will need an FAA STC? we are allowed to put it in German PA28 or French PA28 without STC because as you say "it's acceptable to administrator here"...

Edited December 23, 2024 by Ibra

[PT20J]

4 hours ago, Fly Boomer said:

I think you are on to something here.  As far as I know, all other STCs are free.  I have certainly never paid for one.

The Petersen autogas STC varies by engine make/model and is anywhere from less than $100 to more than $300. The Swift 94UL STC is $100. The GAMI G100UL STC is $400 for an M20J.

[Marc_B]

The fact of the matter that an STC takes money to obtain and you can guarantee you're paying to use that STC whether it's rolled into the product you purchase or if you pay another vendor for the privilege to use it.

The purchase of an STC upfront just means that more of that initial cost for development may be recouped a little faster.  I think the choice here was likely very intentional and it's like poker watching how all the "players" wager and play their hands.

[VetRepp]

I've used the G100UL without any issues, Although this thread has now given me cause for concern. 

The STC was $570, but reimbursed by Airport promotion, so Free

[0TreeLemur]

This morning I saw an article on AvWeb saying that the FBO in Tupelo, MS, has received a shipment of G100UL.  That's about 1 Mooney hour from my home field and the first outside California.  I'm G100UL curious, but the left tank in my J leaks when over about 15 gallons and in that condition I'm unwilling to think about putting it in until this potential compatibility issue is resolved.  I don't want to be an experiment...

BTW I've contacted the company that resealed the tanks in 2018 about getting it patched, but haven't had a chance to get the aircraft to them.

[Marc_B]

49 minutes ago, EricJ said:

I think they could ultimately do that for whatever fuels wind up being in common use.   "Acceptable to the administrator" is the catch-all phrase that makes pretty much anything approved, so if an official administrative action says "You can use X as an approved fuel in place of Y", or "fuel X is approved as a grade 100 fuel", then I'd think that's pretty much done. 

My guess is that we likely WON'T have the FAA weigh in like this until all hands are played.  Currently it's easier to say that a single unleaded fuel option is fungible with 100LL in any amount.  It's a completely different scenario if unleaded A doesn't work with unleaded B even if both work with 100LL independently.

I'm sure the FAA realizes that one of the challenges is to find a fuel that can ultimately be found across the nation and usable with other fuel sources internationally.  I think that is why so much $$ was spent trying to develop a fuel that fit within the ASTM D910 specs as a "universal option."  I think that most involved (including Mr. Braly) feel this is unlikely.

That's a huge win for G100UL so far that it mixes with 100LL and UL94 and doesn't require a new tank...just splash some G100UL in and call mark it G100UL.

[MikeOH]

4 hours ago, Pinecone said:

And how long would it take to get up and running?????

You would need to find a location.  Then deal with the local people fighting a lead plant near them.  That will take years.

Then you have to design, contract, ,build and test the factory.

Since it appears there are at least TWO other countries producing TEL, your point is moot; it would just be a paperwork/permit situation that would need to be expedited in order to buy/import into the US.  This TEL 'going away' is just a red-herring to this discussion, anyway.

[donkaye]

57 minutes ago, VetRepp said:

I've used the G100UL without any issues, Although this thread has now given me cause for concern. 

The STC was $570, but reimbursed by Airport promotion, so Free

I can't emphasize enough about the care that's necessary to prevent staining.  Although I've watched each filling and the men were very careful, I think there must have been some fuel on the bottom of the protector that they put over the gas entry point because I can't get some staining removed even after using every fine abrasive that I can find and spending several hours trying to remove it.  I think I'll take my chances about being charged for dumping the fuel sample rather than trying to make sure every last drop is returned to the tank.  For me the only negative about using this fuel so far.  If the wing weren't white it probably wouldn't show.

[varlajo]

10 minutes ago, donkaye said:

I can't emphasize enough about the care that's necessary to prevent staining.  Although I've watched each filling and the men were very careful, I think there must have been some fuel on the bottom of the protector that they put over the gas entry point because I can't get some staining removed even after using every fine abrasive that I can find and spending several hours trying to remove it.  I think I'll take my chances about being charged for dumping the fuel sample rather than trying to make sure every last drop is returned to the tank.  For me the only negative about using this fuel so far.  If the wing weren't white it probably wouldn't show.

Don, how do you plan to deal with fuel venting caused by thermal expansion in summer? 

[gabez]

I went and check on my plane yesterday they are waiting for some planes to leave the hangar so they can bring it inside and open up the tanks. 

I should have taken pics, maybe I will after the holidays. One new leak from a rivet. I also now have some red-ish drop like stains on top of the tanks. probably from spillage when moving the nozzle. 

[EricJ]

2 hours ago, Marc_B said:

My guess is that we likely WON'T have the FAA weigh in like this until all hands are played. 

That's my expectation as well.    It may take a bit.   I don't see a reason to rush.    The gears are turning faster now than they have in the past, but I'm happy to wait until we have solution(s) that are proven to be safe.

[GeeBee]

2 hours ago, MikeOH said:

Since it appears there are at least TWO other countries producing TEL, your point is moot; it would just be a paperwork/permit situation that would need to be expedited in order to buy/import into the US.  This TEL 'going away' is just a red-herring to this discussion, anyway.

Do those countries TEL meet ASTM specs?

[MikeOH]

1 minute ago, GeeBee said:

Do those countries TEL meet ASTM specs?

You're missing the point.  IF the current TEL plant shut down tomorrow there is NO WAY the US would not find a way to keep 100LL flowing.  It's patently absurd to think all piston GA requiring 100LL would be grounded as long as TEL was available SOMEWHERE.

[GeeBee]

4 minutes ago, MikeOH said:

You're missing the point.  IF the current TEL plant shut down tomorrow there is NO WAY the US would not find a way to keep 100LL flowing.  It's patently absurd to think all piston GA requiring 100LL would be grounded as long as TEL was available SOMEWHERE.

No, I am paying very close attention. Everyone is making the point that you can't transport these chemical compounds unless they are ASTM certified. If you really believe that, then do you think they are going to load 10,000 gallons on a container ship then transport it to a blending facility? If ASTM compliant is indeed a barrier to transport for G100UL then it is for TEL. You all are creating a circular firing squad here.

Secondly, I am old enough to remember the ATC strike in 1981. The government didn't give a flip about GA then (if you tried to get an IFR slot you remember) and they care even less now. 

[T. Peterson]

7 hours ago, A64Pilot said:

Very often STC’s are not free, depends on whether or not the owner is trying to sell their product or make money from the STC, or both maybe. Often the STC cost is small, sometimes not. For instance if the STC is for modifying the aircraft with readily available parts so the STC holders only profit is from the STC, then of course that STC can and should cost more.

As an IA, in my opinion anything that doesn’t require any modification to the aircraft should not by definition require an STC. For the owner an STC is a pain, and even if it’s free they still have to pay an IA to fill out the 337, make logbook entries etc., so free isn’t.

From my understanding this fuel requires no aircraft modifications or changes to operation, is a simple drop in, is completely miscible with other existing fuels, so why does it require an STC?

Just one man’s opinion.

This is exactly right! The entire notion of an STC is that something is being done to the airplane. In this case nothing is being done to the airplane. It’s a drop in fuel that is abusing the STC system to allow GAMI to milk the cow from both ends. Utterly irrelevant that this may have happened with other products in the past. If it did, it was wrong. 
This is also why the semantics matter. It’s not silly, it’s dishonest.

[GeeBee]

12 minutes ago, T. Peterson said:

This is exactly right! The entire notion of an STC is that something is being done to the airplane. In this case nothing is being done to the airplane. It’s a drop in fuel that is abusing the STC system to allow GAMI to milk the cow from both ends. Utterly irrelevant that this may have happened with other products in the past. If it did, it was wrong. 
This is also why the semantics matter. It’s not silly, it’s dishonest.

So an STC that allows a gross weight increase with no modifications to the airplane is abusing the STC system? Is the STC that allows the removal of the 7th seat from a Cherokee Six so it can be flown under basic med abusing the system?

[toto]

4 minutes ago, GeeBee said:

So an STC that allows a gross weight increase with no modifications to the airplane is abusing the STC system?

Just to be obnoxiously pedantic, if you mean the gross weight increase for the J model Mooney, that’s not an STC. It’s part of the original type certificate for the relevant serial numbers. 

[GeeBee]

3 minutes ago, toto said:

Just to be obnoxiously pedantic, if you mean the gross weight increase for the J model Mooney, that’s not an STC. It’s part of the original type certificate for the relevant serial numbers. 

No I do not mean the J model. There are other airplanes with GW increases as a result of STC. The early King Airs being one example.

[toto]

11 minutes ago, GeeBee said:

No I do not mean the J model. There are other airplanes with GW increases as a result of STC. The early King Airs being one example.

Just ignore me then

Carry on …

[GeeBee]

Here is but one example.

http://mcgettrickengineering.com/images/Bonanza N35 and P35 STC More Info_G.pdf

[Marc_B]

Regulatory answers probably found in FAA/USDOT Directive 8110.4C

I suspect that STC was the most direct avenue for GAMI to pursue outside of PAFI/EAGLE--does anyone know what the end result of PAFI was designed to result in??  (i.e. "minor change by Administrator," STC, a blanket Amended Type Certificate from the FAA, or something else?)

STC issued when a modification is made to an already certified aircraft, essentially approving the change without altering the original type certificate itself.  (Vs. Amended Type Certificate that amends the original).

As previous alternative fuels have used the STC process for fuel change (even in the absence of equipment change) this process has precedent.  The big question is if the FAA rules a sweeping change in fuel spec (when 100LL eliminated) as a major change...or a minor change made by the Administrator??  (see below)

 

14 CFR § 21.93 Classification of changes in type design.

(a) In addition to changes in type design specified in paragraph (b) of this section, changes in type design are classified as minor and major. A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes” (except as provided in paragraph (b) of this section).

8110.4C  CHAPTER 4. CHANGES IN TYPE DESIGN
4-2. MAJOR AND MINOR DESIGN CHANGES. The FAA issues amended TCs or STCs
for approval of major changes to type design. The FAA classifies minor and major changes in
14 CFR § 21.93 by outlining what constitutes a “minor change.” As such, the FAA and the
applicant agree on the magnitude of the effects of the proposed change to determine its
classification. In 14 CFR § 21.95, the rule states that minor changes in type design may be
approved under a method acceptable to the Administrator prior to the submittal to the
Administrator of any substantiating or descriptive data. Minor changes to a type design are at a
minimum recorded in the descriptive data, with the FAA and the applicant determining an
acceptable process for approving the data supporting the type design changes. Approval of
changes deemed to be major (14 CFR § 21.97) requires the applicant to submit all substantiating
and descriptive data for inclusion in the type design before FAA approval.