Marc_B

@PT20J thanks for the page. I know they describe the mode but was trying to find if Garmin ever described a flow or stepwise. Makes sense when using FD show a wings level 7 deg climb. Honestly I don’t think I usually pay much attention to the FD right off the deck. Of course I’m not usually taking off in LIFR and that’s probably where it’s most helpful…if it’s remembered/used as pointed out.

Have not heard line up and hold. Typically I’ve heard “Hold Short Runway…” Could see why confusing. I think it would warrant a call to the tower in question to discuss phraseology with supervisor. Taxi into position and hold = line up and wait.

The issue from my perspective is the potential for damage to components has not been publicized and the exact components that don’t play nice with G100UL aren’t listed. Yet airframes with these components are included in the AML. Makes it hard to say who should be concerned and who shouldn’t. I understand that the fuel works in engines. But don’t understand how the AML included every airframe that has components not compatible but yet no STC instructions for ICA and preparation for use??

https://www.aopa.org/news-and-media/all-news/2024/november/pilot/unleaded-fuel-what-we-have-learned# I don’t remember seeing this before. But there are pictures around fuel cap that are suggestive.

Perhaps create an Alternative Fuel forum and move them all there to make it easier?

For clarification, TOGA does NOT engage the AP, but rather just turns on Flight Director. So when anyone is using the TOGA button for take off this is different than engaging AP. According to AFMS, AP should not be engaged below 800’ agl except on approach to land. so we’ve really just talking about how best to set up flight director on takeoff before you engage AP.

@Pinecone I saw Mr. Braly’s response you quoted above on BT. I just wish he’d comment specifically about the content of the video outside of only commenting about the sign at RHV. Does he feel this is consistent with what he’s seen in the lab? Which products did he test in the lab to say this is drop in for almost the entire fleet of airframes and airframe ages? Which compounds, sealants, and hoses/rubber/o-rings should be avoided or used with caution when implementing G100UL? What amount of paint damage is “acceptable” as standard practice use of G100UL? We’ve heard repeatedly “trust the data” but I have yet to see any data from GAMI on the issues we’re discussing.

@midlifeflyer interesting that the AFMS says basically nothing about TO. How do you typically teach programming and using AP leading up to and at takeoff? Curious where press the button as you advance throttle came from and if you use that practice? Certainly understand that with GA…

From a post on BT…not my video.

I don’t think I’ve ever been instructed to push TOGA on takeoff roll and that’s not how I use the AP. Most of the time I get “fly runway heading” or “turn heading…” for an instrument departure. For me (typically single pilot IFR) I set up as much as I can on the ground when I get my clearance and I’m programming GPS. Hand fly till 800 ft and by then I’m either on a heading or already direct to a fix. Rather than TOGA most of the time I use IAS for climb and HDG for initial lateral mode. Sometimes i push TOGA, dial in heading bug and press HDG and leave pitch on TO.

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.

@M20F Already done. But Mr. Braly mentioned this on the forum and I thought this was a good way to open up to others on this forum. I also thought it was easier to separate the thread to make it easier to just keep this independent of any other discussion in the other thread.

@NickG The lens is notorious for delaminating and some of the lenses are not too easy to peel off the shedding skin. The other issue that's been described is the indicator going out due to a blown pico fuse. Also the indication gets jumpy/scratchy from a worn potentiometer. This thread has some good info:

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.

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.

@George Braly Certainly don't want to let this offer pass by. If you were serious, how can we get this set up? Would definitely be interested and I know that others would as well. "Here is a modest proposal: If the Mooney folks would like to learn more, GAMI will offer to host a "Mooney Delegation" here at Ada. Maybe anywhere from 3 to six participants ? I will print out all of the material compatibility test data that the FAA has approved and we can sit down around a conference room and review that. I will answer any questions. In the process you can get a chance to see the engine test cell and maybe have an opportunity to observe while it is run on G100UL vs 100LL vs "other" PAFI/EAGLE type fuel chemistries. There may be some additional items of interest. Let me know?"

@gabez Not sure if you saw Don's mention above. Inclined to agree if you're looking for a more detailed response. "I have used G100UL and I had leaks/paint stain" isn't quite the same thing as "I've seen new/increased leaks since use," "I've seen paint damage," or "I've had paint staining."

My shop does mine and I have a Surefly on the right side. But if I was sending out, I'd use Aircraft Magneto Service in Montana. https://www.aircraftmagnetoservice.net

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.

But I know that that fuel has been tested and that Mr. Braly knows the exact composition. Just wondering if he was going to share the data or even remotely answer in an average. Seems like the answer to that is an unanswered "no."

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.

G100UL looks to be the most promising of the unleaded alternatives and the unleaded train will be arriving all too soon. Fortunately there are plenty of owners who would love to use it now and it benefits us all to have them gain real world experience.

I wouldn’t be surprised if that is true, but I’ve got no clue as to the avg specs of G100UL since they don’t share that…do you know details? Or just making a generalization? SDS shows 20-40% xylene but if Mr Braly is saying 100LL has 29% toluene, and if 100LL - TEL = UL94, then it stands to reason that it must have more aromatics than 100LL…

https://www.autofuelstc.com/stc_specs.phtml Sounds like in some cases no. Depends on airframe.

Why isn't the Mooney M-20-C or Piper Comanche approved? The Mooney and Comanche both experienced vapor lock problems when they were tested. We solved the vapor lock problem but could not overcome pneumatic lock. Pneumatic lock takes place when the fuel boils as it enters the carburetor. The engine then dies due to an over rich mixture. This is just the opposite of a vapor lock where the engine quits or runs poorly due to a lean mixture. The better an airplane performs, the more difficult it is to get it through the flight test program.