4 ms·

…but is exhausting at volume from most small aircraft you see. I say sadly, as an aviation geek; we can do better!

by gilrain 3mo ago

aftbit 3mo ago
We're working on it, slowly but surely. This has been a known problem for a long time, at least since 2009 if not earlier. GAMI's G100UL was approved as a 100LL replacement in 2022, but there is still some controversy. Avweb has done a good series of videos on this. There were some real engineering concerns and some typical aviation conservative decision making. But really, it's a tragedy of the FAA fumbling the ball for decades at this point. https://www.youtube.com/watch?v=9F-WngVMJBQ https://www.youtube.com/watch?v=9F-WngVMJBQ https://www.youtube.com/watch?v=Mvse4Xhzwuk https://www.youtube.com/watch?v=Mvse4Xhzwuk https://avweb.com/features/unleaded-avgas-airport-playbook-lands/ https://avweb.com/features/unleaded-avgas-airport-playbook-l... https://avweb.com/aviation-news/judge-denies-g100ul-motion/ https://avweb.com/aviation-news/judge-denies-g100ul-motion/ https://g100ul.com/ https://g100ul.com/
- Onavo 3mo ago
  A better way would be to switch to mogas and authorize cheap fuel system retrofits and maybe mandate dual FADECs on engines similar to the ADS B requirements. Your modern general aviation pistons can easily handle mogas. An even better way would been to encourage the migration to turbines and deprecate pistons entirely. Jet A (diesel) for the win. The new turbotechs regenerative turbines are a lot more reliable (3000 hours TBO). https://cubcrafters.com/c/2026/07/press-release-cubcrafters-introduces-the-new-carbon-cub-ult/ https://cubcrafters.com/c/2026/07/press-release-cubcrafters-... Pistons suffer from too many reliability issues (especially if you don't have a MX team on call like a commerical operation). I am not sure why the aviation industry (and the FAA in particular) is obsessed with keeping around almost-a-century old lawnmower engines (Yes your Cessna Skyhawks, if you trace them back to their predecessor, are from the WWII days). Learning to "lean an engine" never made me a better pilot and there's a reason FADECs are used everywhere else. It's a very big problem because most of the big general aviation players (Cirrus, Diamond, Continental, a bunch of others) are snapped up by Chinese conglomerates (they don't have general aviation in Asia but they have a growing number of flight schools, not sure how that works) now and they are hardly known for their expertise in piston engines. People buy Chinese EVs, nobody buys Chinese ICE cars. Diamond owners had to ground their planes for over 2 years because Diamond couldn't figure out how to do a Mercedes OEM license-built piston head properly. The Chinese-built pistons kept cracking and required boroscope engine inspections every 50 hours (notoriously expensive and not covered by warranty, they only managed to solve the cracking problem recently). So much for supposed Chinese manufacturing prowness. Imagine buying a fancy Porsche car and only to be told that you have to keep it in the garage most of the year because the car company got bought out and the new owners don't know how to produce a proper piston. Owners would riot. Sadly general aviation operators are trained to take it up the ass like a good little pilot because the dinosaur FAA (for whom general aviation is their lowest priority, about the same importance as hot air balloons) mandated that the OEM's word is literal law and if it's grounded then too bad.
  - aftbit 3mo ago
    As I understand it, a big part of the problem is that the general aviation market is too small to justify the expense of getting new designs certified. Also, it seems baked into the regulations that the old design was "good enough", so it still is today, even though technology has moved on. When people are building experimental class piston airplanes with better features, reliability, and performance than the certified world can muster at half the price, you know something has gone wrong.
    - aidenn0 3mo ago
      I believe liability is an issue too. In aviation (as compared with autos) the manufacturer is often found partially liable for an accident, so they can be on the hook even if it was mostly the fault of the operator.
      - Onavo 3mo ago
        It's worse now, people are doing "51% Build Assists" (most famously Vans and Sling aircraft) to save money where the factory would give you an IKEA plane kit and you will maybe put in a few screws and decals and install the avionics panel and you will sit in the room and watch them assemble the rest of the plane "under your supervision". Then the whole thing will get penciled whipped as an Experimental Owner-Built aircraft and if anything goes wrong it's entirely the fault of the owner and not the factory, because the layman hundred hour PPL pilot is supposed to be a master of aerospace engineering. I think MOSAIC is the only thing the FAA got right in the recent years when it comes to general aviation.
        MichaelZuo 3mo ago
        Isn’t it better? Some people dont want to pay the extra overhead and cost burden of the manufacturer taking partial liablity. They’re willing to take a risk.
        Onavo 3mo ago
cucumber3732842 3mo ago
There's an equal and opposite person who'll be screeching about safety if you try and monkey with the fuel. That's exactly why this is taking so long. There's no free lunch.
- JumpCrisscross 3mo ago
  > an equal and opposite person who'll be screeching about safety Unleaded avgas isn't as standardized as 100LL. (To my knowledge, there is no dying convention for its different octane ratings. So you can't draw fuel and confirm, visually, that someone didn't put something in your tanks that's going to knock your engine.)

…but is exhausting at volume from most small aircraft you see. I say sadly, as an aviation geek; we can do better!

by gilrain 3mo ago

…but is exhausting at volume from most small aircraft you see. I say sadly, as an aviation geek; we can do better!

We're working on it, slowly but surely. This has been a known problem for a long time, at least since 2009 if not earlier. GAMI's G100UL was approved as a 100LL replacement in 2022, but there is still some controversy. Avweb has done a good series of videos on this. There were some real engineering concerns and some typical aviation conservative decision making. But really, it's a tragedy of the FAA fumbling the ball for decades at this point. https://www.youtube.com/watch?v=9F-WngVMJBQ https://www.youtube.com/watch?v=9F-WngVMJBQ https://www.youtube.com/watch?v=Mvse4Xhzwuk https://www.youtube.com/watch?v=Mvse4Xhzwuk https://avweb.com/features/unleaded-avgas-airport-playbook-lands/ https://avweb.com/features/unleaded-avgas-airport-playbook-l... https://avweb.com/aviation-news/judge-denies-g100ul-motion/ https://avweb.com/aviation-news/judge-denies-g100ul-motion/ https://g100ul.com/ https://g100ul.com/

Onavo 3mo ago
A better way would be to switch to mogas and authorize cheap fuel system retrofits and maybe mandate dual FADECs on engines similar to the ADS B requirements. Your modern general aviation pistons can easily handle mogas. An even better way would been to encourage the migration to turbines and deprecate pistons entirely. Jet A (diesel) for the win. The new turbotechs regenerative turbines are a lot more reliable (3000 hours TBO). https://cubcrafters.com/c/2026/07/press-release-cubcrafters-introduces-the-new-carbon-cub-ult/ https://cubcrafters.com/c/2026/07/press-release-cubcrafters-... Pistons suffer from too many reliability issues (especially if you don't have a MX team on call like a commerical operation). I am not sure why the aviation industry (and the FAA in particular) is obsessed with keeping around almost-a-century old lawnmower engines (Yes your Cessna Skyhawks, if you trace them back to their predecessor, are from the WWII days). Learning to "lean an engine" never made me a better pilot and there's a reason FADECs are used everywhere else. It's a very big problem because most of the big general aviation players (Cirrus, Diamond, Continental, a bunch of others) are snapped up by Chinese conglomerates (they don't have general aviation in Asia but they have a growing number of flight schools, not sure how that works) now and they are hardly known for their expertise in piston engines. People buy Chinese EVs, nobody buys Chinese ICE cars. Diamond owners had to ground their planes for over 2 years because Diamond couldn't figure out how to do a Mercedes OEM license-built piston head properly. The Chinese-built pistons kept cracking and required boroscope engine inspections every 50 hours (notoriously expensive and not covered by warranty, they only managed to solve the cracking problem recently). So much for supposed Chinese manufacturing prowness. Imagine buying a fancy Porsche car and only to be told that you have to keep it in the garage most of the year because the car company got bought out and the new owners don't know how to produce a proper piston. Owners would riot. Sadly general aviation operators are trained to take it up the ass like a good little pilot because the dinosaur FAA (for whom general aviation is their lowest priority, about the same importance as hot air balloons) mandated that the OEM's word is literal law and if it's grounded then too bad.
- aftbit 3mo ago
  As I understand it, a big part of the problem is that the general aviation market is too small to justify the expense of getting new designs certified. Also, it seems baked into the regulations that the old design was "good enough", so it still is today, even though technology has moved on. When people are building experimental class piston airplanes with better features, reliability, and performance than the certified world can muster at half the price, you know something has gone wrong.
  - aidenn0 3mo ago
    I believe liability is an issue too. In aviation (as compared with autos) the manufacturer is often found partially liable for an accident, so they can be on the hook even if it was mostly the fault of the operator.
    - Onavo 3mo ago
      It's worse now, people are doing "51% Build Assists" (most famously Vans and Sling aircraft) to save money where the factory would give you an IKEA plane kit and you will maybe put in a few screws and decals and install the avionics panel and you will sit in the room and watch them assemble the rest of the plane "under your supervision". Then the whole thing will get penciled whipped as an Experimental Owner-Built aircraft and if anything goes wrong it's entirely the fault of the owner and not the factory, because the layman hundred hour PPL pilot is supposed to be a master of aerospace engineering. I think MOSAIC is the only thing the FAA got right in the recent years when it comes to general aviation.
      - MichaelZuo 3mo ago
        Isn’t it better? Some people dont want to pay the extra overhead and cost burden of the manufacturer taking partial liablity. They’re willing to take a risk.
        Onavo 3mo ago

cucumber3732842 3mo ago

There's an equal and opposite person who'll be screeching about safety if you try and monkey with the fuel. That's exactly why this is taking so long. There's no free lunch.

JumpCrisscross 3mo ago
> an equal and opposite person who'll be screeching about safety Unleaded avgas isn't as standardized as 100LL. (To my knowledge, there is no dying convention for its different octane ratings. So you can't draw fuel and confirm, visually, that someone didn't put something in your tanks that's going to knock your engine.)