The Future of 100LL

[Pete of N978PB]

Good People ~

In this week's edition of AvWeb there is an interesting article by a chap named John Deakin pertaining to the future of 100LL avgas.

Since our beloved IO-470s run on the stuff, it is a worthwhile read for many of us.

Deakin claims that (1) 100LL has no future and gives his reasons why and (2) there is already available a system developed by GAMI known as "Prism" that solves the no-lead detonation problem and will allow use of what he calls "95LL" throughout the GA fleet.

It's at http://www.avweb.com/articles/pelperch/pelp0055.html

Pete

[Todd Peterson]

The article on 100LL was very interesting and pointed out a few facts that I've been trying to make for years. When someone asks me about the future of the IO-470 engine (in that it's certified for 100LL) I tell them to look at the segment of aviation that uses most of the 100LL. Most of the aircraft are buisness type airplanes in the upper end of the aviation scale. Singles, turbo singles, turbo twins, etc. No one is going to stop the production of the fuel the upper end aircraft must have. Now on the other hand if the majority of 100LL was used by ultralights, tripacers, champs, etc. there might be a problem.

Whatever the new fuel is they are going to eventually come out with there are going to be some engines, as mentioned in the article that are going to have a hard time because they are already so prone to detonation. Fortunately the IO-470 is not one of them. The STC we have is loosely based on an FAA field approval issued to a gentleman in NM for this engine in his Wren. At the time I met him he had flown his Wren with the IO-470 engine for 2,400 hrs on unleaded auto gas! During this time he had not overhauled the engine nor had he experienced any problems. He used the auto gas as he flew from his ranch and it was just easier to stock one type of fuel for all his vehicles.

Bottom line is when a replacement for 100LL comes out it will work fine in our beloved IO-470 engines.

[witrakw]

Todd's comments about running the wren's IO470 on auto unleaded gas for a prolonged TBO and "without problems" again begs the question of: with all the 470 engines out there and even despite of the cost of stc'ing the engine for unleaded gas, wouldn't there be a market for doing so? From my novice mechanical eyeballs, it seems that the only engines that lead or other toxic additives benefit are the engines that are prone to detonation.

A large number of other non detonation prone engines just get gummed up with lead deposits and blowby products. If you discount most of the "Old Wives' Tales" (Deakin) on why lead is good for an engine, then why isn't there a serious attempt to dump it and at least establish a dual tier the aviation gas market?

It would be of interest to know the flight and usage parameters of the wren that you refer to since the main negative and concern about "automotive fuel" appears to relate to its relatively lesser quality control and nonuniformity which "may" lead to detonation.

Having grown up on a farm(sort of like a ranch), I can't think of a much more nonuniform gas source that that of a potentially rusty, thunderstormed on, gummed up, elevated farm(ranch) gas tank with the John Deere tractor filling up at its side!!

Anyway just some ignorant thoughts.
I am glad to be joining all your 260se ranks soon.

Say Todd, is this a new STC for you to pursue???

N759MU Bill Witrak

[Todd Peterson]

I don't really think it would be practical for me to try and certify auto gas for the IO-470. It would probably be better for someone that currently has auto fuel STC's to attempt it.

It is my understanding that one of the problems in using auto gas in these engines is with the problem of an increased chance of vapor lock. The chance of this is evidentally much greater in a fuel injected engine than a gravity fed engine. The gentleman that run his Wren on premium unleaded auto gas lived outside of Roswell, NM and I would guess it gets pretty hot there during the summer. In spite of this he said that he had no problems in using this fuel.

If caught out in the middle of nowhere I would not hesitate to use some premium unleaded auto gas added to the 100LL already in the fuel tanks to get me out of a bind.

[fsbrb2]

Has/Is Todd looking into the new 'deisel' engine options as a possible future alternative to the 100LL issue?

[Todd Peterson]

No, I haven't given serious thought to the diesels and probably won't for quite some time. After having been in this business for over 30 years I need to see some things happen before I would really give it serious consideration.

First off certification has to occur (preferrably with more than one company), then a firm price has to be determined ( I think SMA figured their complete engine/prop/cowl package at $80,000), price has to be reasonable, then many installations need to be made and flown in the field for a number of years to work out all the problems that will spring up, and a good nation wide system of service centers need to be set up.

While I think there might be some potential benefits the total picture won't be known for many, many years.