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FAA Wants All Aircraft Flying On Unleaded Fuel By 2018
coondoggie writes "The Federal Aviation Administration (FAA) this week put out a call to fuel producers to offer options that would safely let general aviation aircraft stop using leaded fuel by 2018. The FAA says there are approximately 167,000 aircraft in the United States and a total of 230,000 worldwide that rely on the current 100 octane, low lead fuel for safe operation. It is the only remaining transportation fuel in the United States that contains the addition of tetraethyl lead, a toxic substance, to create the very high octane levels needed for high-performance aircraft engines. Operations with inadequate octane can result in engine failures, the FAA noted."
It's piston-engine stuff like Cessnas that make up the remaining leaded avgas users, and even there, only the subset of engines that require the 100-octane avgas. Both newer and some older stuff can use 91-octane stuff that's now unleaded.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
The issue is not with airlines (which use Jet fuel) or with Commercial operations (mostly using newer engines). It is with the flight schools and other General Aviation users.
The problem with leaded fuels is not really that technology to use unleaded is not available, but that most of the General Aviation Fleet that is flying is older technology. Majority of the GA fleet are from 1970's or 80's when Cessna and Piper dominated the market.
Then came lawsuits (frivolous and otherwise) and most of the manufacturers filed for bankruptcy. The airplanes from the 90s tend to be mostly homebuilt. Post 2000s a lot of the companies came back from bankruptcy and started making airplanes again. The only problem is that a new Piper costs about $200K while a perfectly usable 1970s Piper with overhauled engine and modern avionics is only about $30K. Airplanes last a lot longer than cars if regularly maintained. So most flying crafts tend to be old.
So these older planes which were designed for leaded gas get recertified for low lead gas, but can never use unleaded.
Newer aircrafts tend to do two things,
1) Run on motor gas (mostly involves certifying for unleaded gasoline) . This has the nice side effect that the gas tends to be about 30% cheaper.
2) Run on Diesel/Jet Fuel / Kerosine - In this case it sidesteps the entire lead problem and also avoids using spark plugs (depending on the design). Fuel availability is a lot better, though not always cheaper.
One easy solution is to make unleaded mandatory for any Light Sport aircraft (which tend to be the newer airplanes built) and to increase a fee imposed while overhauling older engines (which get done every 1000 hours).
That said, this move would permanently ground the WW2 display fleet that is currently flyable and a bunch of old Piper Cubs and Ercoupes. But they are all pre-ww2, so not a big loss I guess.
http://slashdot.org/submission/1062723/Cheap-mobile-data-plan?art_pos=2
No, and you can tell this from the first line in TFS: "The Federal Aviation Administration (FAA) this week put out a call to fuel producers to offer options that would safely let general aviation aircraft stop using leaded fuel by 2018."
They want fuel producers to offer options that will meet the need of aircraft that are currently dependent on leaded fuel to operate properly without lead.
I get that its a lot to ask you buy a new engine, or even to RTFA, but could you at least bother to read the first sentence of the summary before exploding with outrage next time?
Yeah, its a good thing that the FAA isn't talking about new engines at all, but instead calling on fuel producers to come up with replacement fuels that will work in current engines. Which is stated not only in TFA, which I can understand is a huge bother to read before complaining, but in the first sentence of the summary, as well.
I used to do analytical work on fuel certification in a refinery, and while I didn't measure the "octane number", I understand what it means.
The number 100 refers to the performance of pure isooctane (2,2,4-trimethylpentane) as a fuel - isooctane is simply a reference for the "100" rating. Fuels are assigned a higher number when they are tested and shown to have a lower tendency to undergo premature ignition in an internal combustion engine (this phenomenon is known as knocking). Such premature ignition occurs when fuel and oxidant in a hot engine cylinder are compressed as part of normal operation of the engine and is more probable when the fuel has a lower activation energy for combustion and fewer radical scavengers are present in the fuel mixture.
Other compounds (aromatics like toluene and xylene isomers, tetraethyllead, methylcyclopentadienyl manganese tricarbonyl ) also enhance the "octane" number. The latter (MMT) is routinely blended into automotive gasoline in Canada despite being a known heavy metal/neurotoxin with likely worse long-term effects than tetraethyl lead (...!).
Among these various options, the straight hydrocarbons are far preferable and can be used without modification of engines to accomodate the exclusion of lead.
The only reason the heavy metals are used is to reduce the cost of filling one's tank.
the lead in petrol had a few benefits, it raised the octane number, allowing the engines to have higher compression ratios, providing better thermal efficiency of the engine. Also in the era when engines where made from detroit wonder metal (cast iron) certain parts were lubricated by the lead, so they could remain as cast iron, such as valve seats, whereas unleaded fuel has required hardened valve seats to be inserted.
Mix two different octanes of avgas together and the dyes disappear. It is a feature of avgas to alert pilots in case they mix octanes.
Bullshit. You clearly have *NO* clue how general aviation works. Anyone can go to the airport with a gas can and use the self serve station. Records are not kept. You do not have to own an aircraft to buy avgas. People at the airport here use it in the lawn mowers, the tugs, golf carts, chainsaws, etc. Hell, I use it in my 2-stroke RC car. I've bought 100LL all over the state on my personal credit card for aircraft I don't own.
Don't present as fact that which you have no clue about.
They are also much lower volume production than car engines. The designs are different enough that it isn't easy to just substitute automobile engines for aircraft use. Its been tried, and has worked in some cases, but not many.
Basically aircraft engines turn slowly (usually 2700 rpm max) because the propeller tips need to stay subsonic. Gear boxes are very heavy because of the large moment of inertia of the propellers and haven't worked very well in most installations. The low engine speed means that it needs very large displacement (9 liters is not uncommon) to get the required power. Light weight / high airflow give you air cooled, aluminum-finned engines. The aircraft engines are actually very efficient at their normal operating point. Part of this is due to the high compression allowed by high octane fuel.
I have been checked 6 times in 12 years on my personal diesel. On my heavy equipment we average 1-2 checks per year per vehicle. This is in Alabama and Georgia.
But when I put it in my motorcycle, whooopeeee! Goes like a rabbit!
Not unless you changed the ignition timing, raised the compression, or did anything else that could benefit from higher octane. Otherwise you spent a bunch of money for a gasoline-flavored placebo.
It also smells different. I don't know why.
Mercaptans, organic compounds that occur naturally in crude oil. They seriously stink; methyl mercaptan is what your gas company puts in the gas so you'll know when you have a leak, and T-butyl mercaptan is essence of skunk. Get car gas on your hands, wash with soap and water, and you'll still smell the mercaptans.
Mercaptans also congeal with age and gum up fuel systems. Aircraft operators take that a little more personally than car owners do, so avgas has the mercaptans refined out.
There have been some improvements in propellers - Hartzell makes some "scimitar" shaped propellers that are a bit quieter and marginally more efficient. Not a lot to be gained though since standard propellers are pretty high efficiency (maybe 90%?).
What you are suggesting is using smaller diameter propellers that turn faster. There unfortunately you are fighting aerodymaics. Propellers are wings. Wing tips add drag, so you want as few as you can. Thin wings are more efficient than fat wings. This pushes you to a small number of small thin blades - and 2-blade, think props are what you see on small aircraft.
There is a limit though in how much power a 2 blade thin prop can deliver so as engine power goes up, you get more blades (3, 4, sometimes ~7 on prop airliners), and the blades get fatter. This all decreases efficiency, but there seems to be no way around it. So, you could go up in prop RPMs but the loss in efficiency so far hasn't been worth it. With a single engine plane its also difficult because if the prop gets smaller in diamter, it is mostly shadowed by the fuselage of the aircraft. Twin (or more) engine planes can have smaller props out on the wings (and some do), but that is a small part of the general aviation market.
Before someone asks: piston engines are more efficient than turbines, but much worse power to weight. Large aircraft use turbines because the power to weight is so high that they can get to very high altitudes where the air is thin and there is low drag at high speeds. Flying that high really requires a pressurized cabin, so you don't see many turbines on small aircraft.
the lead in petrol had a few benefits.
It was never worth the cost
http://www.economist.com/blogs/theworldin2013/2013/01/lead-and-crime
http://www.forbes.com/sites/alexknapp/2013/01/03/how-lead-caused-americas-violent-crime-epidemic/
http://blog.caranddriver.com/pb-and-jail-new-research-ties-leaded-gas-ban-to-drop-in-violent-crime/
http://www.motherjones.com/environment/2013/01/lead-crime-link-gasoline
http://www.medicaldaily.com/articles/13789/20130107/leaded-gasoline-linked-rise-fall-violent-crime.htm