While at Oshkosh 2013 Aviat had a pretty blue Husky that could run on Avgas (100LL) or CNG (130-ish Octane and no lead), giving a lead-free and cheaper per-mile alternative. After KOSH there hasn't been much more in the way of announcements for the engine technology or the aircraft. Granted, Dodge came out with a RAM that could run on CNG or dino juice. That was about a decade and a half ago but it never took off even though a lot of people have natural gas connections at their homes.

This seemed to be a great option for Aviat based upon the literature but I was really interested in options on other production aircraft. The rumor was that it was coming, but I never saw anything more about it.

Is CNG dead for aircraft?

A few links that highlight this:
http://aviationweek.com/blog/aviat-unve ... 1c-oshkosh
https://www.wired.com/2013/07/cng-airplane/
https://www.planeandpilotmag.com/articl ... LtoRndFyUk

I think that if you are going to talk training aircraft that pretty much stay in the pattern, electric planes will accomplish that cheaper and in a far less complex manner than CNG planes. I doubt CNG aircraft could generate the same power, and certainly no the same range as an Avgas plane. Having what amounts to a compressed gas fuel tank hanging under your seat might give some pilots pause when considering what might happen in an accident...but in reality, the CNG tank may be less risky than liquid fuel in the wings. Most likely, CNG will be used to generate the electricity that will power electric training planes of the future, but not directly power the planes.

If you are talking electric planes and putzing around the pattern or flying short cross-countries - At Oshkosh 2015 I got to check out the Airbus E-fan and my kids loved it. I had really looked forward to building some relatively carbon neutral multi time at approx $150/hr and around $200/hr for the eFAN 4. If one engine and a chute is safe, 2 engines and a chute are safer. At the time Airbus would not take any deposits.

Now that you put it that way, I don't know which makes me more nervous, sitting on a potential bomb with shrapnel, sitting in front of a potential firebomb that can melt through concerte, or sitting between 1/2 of the components of a potential FAE. Now that I think of it, I am a lot safer sitting in my house typing on BeechTalk and watching Air Wagner videos posted by Jerry.

That husky was DOA. The weight of the tank was a nonstarter. That’s why it ended up at only 11gal of CNG I think.

My brother had a small commercial truck that ran on CNG. There was a tax angle and it had a low per mile cost. In the end, with driving time limitations on his driver it made no sense to have someone waste time at a fueling station rather than on the road. Given the weight of even composite tanks, I can’t believe anyone thought this was a good idea for a light plane.
Some years back someone spoofed a april 1st press release from Diamond announcing a Da42 that would run on coal. Made light of the companies stubborn pursuit of aircraft run by anything but 100LL.