100LL Fuel Availability

Ernie Martin · #1 08-03-10, 10:00 PM

Good information in the May and July issues of AOPA Pilot Magazine on 100LL fuel, which leads me to this question: does anyone know the compression ratio on our engines?

To get your attention, one of those issues has a statement I had never seen before, saying that 100LL will "certainly" not be available 1n 10 years. I had seen "probably" but not "certainly".

The issues report on considerable work being done to come up wih a solution, including the possibility of alternative fuels.

What most intrigued me was that most aircraft piston engones (~ 70%) can operate satisfactorily on avfuel without lead -- essentially 100LL but without the lead additive. These engines are those with compression ratios of 7.5 to 1 and below, where the lower octane (much less than 100) would be adequate. Only higher performance engines -- including turbos -- need the higher octane.

So the fix is easy for 70% of the engines (just remove the lead) but much tougher for the remaining 30% with higher compression (here, an alternative high-octane fuel and modified ignition systems with variable timing based on sensor data are some of the solutions being studied).

I'm starting this thread, not just with the compression ratio inquiry, but also as a catalyst for more discussions and views on the subject.

Ernie

CO_Skymaster · #2 08-03-10, 11:04 PM

I've gotten a headache from following this issue. I looked up the compression ratio for our engines (TCM IO-360) on the internet. It's 8.5:1, making it one of the engines that will need modification. I've seen suggestions from FADEC, down to adjusting the timing, to placing some type of insert between the core and cylinder (increasing the volume, and reducing compression ratio). I've decided that whatever happens, I will adjust to the new procedures and specs for running my engine. I know there will be changes, but I don't believe all the doom and gloom surrounding the issue.

Karl

stratobee · #3 08-04-10, 01:41 AM

That could be a solution. A de-rating of the engine and less useful payload.

The new 250hp RR300 turbine in the Robinson R66 is an interesting development and could potentially be a good fit for a turbine conversion for those who have too much money.

wybenga · #4 08-06-10, 10:08 PM

Hi Ernie

Continental "Mobile Al" has made a statement that the TSIO-360 will be approved for UL 94, which is 100LL without the lead. Does not look like a severe problem for our airplanes

Jack
reims P337 N1049D
Malibu N26PG
________
MEDICAL CANNABIS SEEDS

Ernie Martin · #5 08-07-10, 12:16 AM

Great news, although it seems to run counter to what I've been reading, if the compression ratio is indeed 8.5:1.

Ernie

CO_Skymaster · #6 08-07-10, 07:37 PM

If that's true, it would be great news. I haven't heard anything. TCM seems to be very closed mouth about any of their projects. They tend to come out and say it exists, then you never hear anything about it again.

Karl

wybenga · #7 08-07-10, 11:33 PM

This is basically the story that TCM has been telling the 100LL consortium. Lycoming, on the other hand, is kicking and screaming all the way saying that their engines will not be able to use 94UL. Same compression ratios and similar boost pressure. Go figure

Jack

N1049D 1975 Reims P337
N26PG 1990 PA46-350
________
Headshops

hharney · #8 08-09-10, 04:25 PM

The way I see it, the engine manufacturers are to blame. They have had years to come up with a solution. How long ago was leaded fuel banned? They have just sat on their hands and not explored the alternatives that could have solved this by now. Every time we turn around there seems to be something else that is trying to keep us from having the freedom to fly our aircraft. The other outside vendors that are trying to develop such alternative fuels will have a license to steal if approved. It will ultimately end up costing more money to fly and comply. The world is changing for us. It will kill general aviation as we know it.

I am going to love it as long as I can.

Coming soon ........................ SOAPA 2011, stay tuned.

WebMaster · #9 08-09-10, 10:35 PM

Mistral was developing a rotary (Wankel) aircraft engine, but their funding dried up. It was to be a true multi fuel engine, quite comfortable on 90 Octane unleaded fuel. In fact, the performance charts are based on 90 Octane unleaded. The turbo, 230 HP engine weighs 328 pounds. Not a lot heavier than the IO-360.
The problem with Continental, and Lycoming, is that they don't have an engineering staff, or funding, to bring a lot of new engines to market. Add to that the variable configurations that they make. If they decided they would make a 550, and it would produce 350 HP, and then tell the airframe manufacturers, that is the product, deal with it, the airframe manufacturers would all be up in arms. The 550 is in a lot of different airframes, with power ratings from 280 to 350 HP. Makes no sense.

wybenga · #10 08-10-10, 05:16 PM

As most you you realize, SOAPA and all consumers of 100LL avgas are now part of the political process by which the transition to an unleaded fuel will be determined. The next urgent call to action is our response to the EPA's Advanced Notice of Proposed Rule Making. The attached letter (complements of Dave Duntz of the Aerostar Owners Assn) is a template for your individual response. Please download it and modify as you see fit to make it your own, sign and mail. Please CC me as well and I will forward to the correct contacts at AOPA. This is a first opportunity for a letter writing campaign. Any letters must be received by EPA no later than August 27, so please do not delay.

I need EVERY member to take this seriously, whether you burn avgas or jetA, makes no difference. This is about the GA economy. Feel free to distribute the template to others so everyone can get involved.

Date

EPA Docket Center (Air Docket)
US Environmental Protection Agency
1200 Pennsylvania Avenue NW, Mail Code 6102T
Washington DC 20460

ATTENTION: DOCKET ID No. EPA-HQ-OAR-2007-0294
Federal Register Volume 75, No 81, April 28, 2010, Page 22440-22468

Dear Administrator:
I own an FAA certified general aviation aircraft with a high compression piston engine that must operate on 100 octane avgas. I use my aircraft for both business and personal use. It is a serious personal investment and an essential tool for efficient travel. I am concerned that a date may be set by the EPA to require reduced lead emissions that is premature and could render the use of my plane non flyable or unsafe without major modifications. I oppose any rulemaking on lead emissions for piston engine aircraft at this time or in the near future until the following critical steps are accomplished first:
1. The process for approval of any new fuel is clearly defined by the FAA and the authority of the EPA and FAA are clarified. Stakeholders in fuel development need to know what they have to do for approval.
2. A viable 100 octane alternative aviation fuel is developed and fully tested. There is no viable 100 octane alternative at this time. A viable 100 octane alternative must provide the same engine performance and margin of safety in high compression engines at a comparable price in all flight conditions as 100LL. It must be mixable with current 100LL and handling and burning must not be any more toxic than current 100LL. Complete testing must involve fleet tests on a variety of high compression piston aircraft in real world conditions with adequate duration to allow significant time on the engines and teardowns to inspect and analyze internal parts.
3. A realistic timeline supported by industry that provides any necessary infrastructure changes for refining, transportation and storage is developed.
4. A realistic transition period supported by suppliers, users, and retailers is defined to allow for using both current and new 100 octane that minimizes impacts to users and retailers.
Because of the widespread use of high compression engines in general aviation, not having a viable 100 octane fuel replacement available by some prematurely determined date for new lead emissions will have a significant negative financial impact to owners. Grounding these aircraft or modifying the engines because a viable 100 octane replacement is not available is not acceptable.
I strongly disagree with any rulemaking on lead emissions for piston engine aircraft until a viable 100 octane alternative exists, and achievable timelines for making infrastructure changes and the transition are agreed upon by all stakeholders.
Sincerely,
Cc: AOPA, Type Club
________
Bubbler Pipe

CO_Skymaster · #11 08-12-10, 11:43 PM

http://www.aero-tv.net/

has a good interview with the CEOs on the fuel issue. I didn't pick up a lot of specifics, but I enjoyed watching it.

Karl