Shell develops unleaded AVGAS

[Katamarino]

Shell reveals unleaded avgas - AOPA

Shell Aviation, a subsidiary of the multinational oil giant Royal Dutch Shell, announced Dec. 3 that a 10-year effort in the laboratory has produced a fuel that may put a long-sought goal—once thought to be unattainable—within reach: a lead-free “performance drop-in” replacement for 100LL that could power any aircraft in the piston fleet.

“That’s our definite goal,” said Michael Sargeant, avgas commercial aviation manager for Shell Aviation, in a phone interview, when asked specifically about the ambition to produce a “performance drop-in” avgas replacement. “We’ve tested it and had some exciting and successful tests.”

The lead-free formulation has a motor octane number (MON) over 100, a critical factor in formulating a fleetwide fuel that could power high-compression engines. (Octane prevents premature ignition known as detonation, and is measured by more than one scale.) Shell’s new lead-free formula has passed preliminary tests in Lycoming engines on the ground, and a Piper Saratoga recently flew for about an hour on the fuel, according to a news release from Shell—the first of many tests that will be required for certification.

“It’s an exciting milestone,” Sargeant said, adding that the company looks forward to working with manufacturers across the general aviation industry, and various regulatory agencies. The company will pursue fleetwide certification rather than a model-by-model approach. Sargeant said tests done on the new formula to date “indicate that it’s a great candidate for fleetwide approval.”

The exact path that Shell must navigate to gain such approval remains to be established. The FAA has a goal of deploying a lead-free piston aviation fuel by 2018, though Sargeant said the company may be able to achieve required approvals and start distribution sooner than that.

“We believe two to three years might be possible,” Sargeant said. “That’s the timeframe that we would love to work towards. The details need to be developed.”

Sargeant said another design goal is to keep the retail price similar to avgas, though it is too early to know exactly what the new fuel would sell for. Shell has only just begun conversations with the various regulatory agencies involved. The fuel will be submitted for approval from the FAA, ASTM, and the European Aviation Safety Agency.

“AOPA welcomes Shell’s announcement of their development of a lead-free potential replacement for avgas and their engagement of the aviation industry,” said AOPA Vice President of Regulatory Affairs Rob Hackman. “We look forward to learning more about Shell’s fuel and efforts as they work with ASTM, FAA, and EASA to achieve the approvals needed to ensure the safe operations of the general aviation fleet.”

Lycoming Engines Senior Vice President and General Manager Michael Kraft praised Shell’s effort in a news release:

“They engaged Lycoming to test their fuel on our highest octane demand engine and we can confirm that it’s remarkably close to Avgas 100LL from a performance perspective,” Kraft said. “This initiative is a major step in the right direction for general aviation.”

Shell is now among three companies that have announced unleaded formulations that could replace avgas in piston aircraft in a matter of just a few years, pending additional testing and regulatory approval. Shell is by far the largest of the companies known to be developing unleaded aviation gasoline. Sargeant said that Shell’s research team has been focused on finding a single fuel that can work for all, rather than a multi-fuel approach with different formulations to meet varying engine requirements.

“The industry doesn’t need bifurcation,” Sargeant said, noting that the company envisions making it possible by licensing or other means for other petroleum producers to manufacture and distribute the formula, which is made from existing components and will not require major changes to the production and distribution infrastructure.

“We think the secret going forward is really working with as many experts as possible,” Sargeant said.

[tomtytom]

Excellent!

Does that mean i will soon be able to claim points on my star reward card?

Tom

[wrecker]

We already have UL91 is the object to produce UL100?

[Katamarino]

Yes, this is a direct replacement for Avgas 100LL for all engines; not just for low compression engines.

[A and C]

Wrecker

There are a wide range of aircraft that can't use 91UL ranging from the humble Cessna 152 to the big turbo charged twins, without a 100LL replacement fuel these aircraft will be increasingly expensive to fly.

The big problem from the supply point of veiw is that you can't mix the leaded fuels in the refinerys with unleaded fuels resulting in having to have a refinery dedicated to 100LL. If you can make a 100 grade aviation fuel without the lead you can use any motor fuel refinery to make the base product, and so keep the cost down.

100UL would also be less harmfull to the environment but this is not a big environmental issue as AVGAS makes up such a small proportion of the hydrocarbon fuel that is burnt.

[Jan Olieslagers]

The main environmental issue is the emission of lead, and this is equally dealt with by Total's UL91 and this new 100UL.

However 91UL was technically unable to universally replace 100LL (for lack of octane, making it unsuitable for most aerobatic and turbo-charged engines), and commercially unable to replace MoGas (far too expensive).

[westhawk]

Another benefit

Though the use of 100LL has always been allowable in aero engines with a minimum octane rating requirement of 80, lead fouling of the spark plugs has been a problem in low compression engines. With no TEL in 100UL, it seems the lead fouling problem with these engines would also be solved. No more need to add TCP to 100LL to aid in the scavenging of lead.

With Shell mentioning the possibility of licensing the formula to other producers, this really begins to look like a very positive development for avgas users.

westhawk

[GOLF_BRAVO_ZULU]

Serious question; do those engines that can now use this already have hardened valve seats?

[Big Pistons Forever]

Be interesting to see how much more green 100 costs. In North America, refineries don't classify 100 LL as a "fuel" it is a "specialty chemical" because of the low volumes. This tiny demand and the need for a dedicated separate distribution system will IMO drives the price up which reduces demand which leads to further price increases to cover costs etc etc.

Jet A powered certified piston GA aircraft is IMO the only viable long term solution.

[Silvaire1]

Serious question; do those engines that can now use this already have hardened valve seats?

They are standard aircraft engines - the hardened valve seat thing for older cars and motorcycles using unleaded fuel was largely a UK theory, promulgated after some areas worldwide had been successfully (and by necessity) using unleaded in unmodified older vehicles for years.

I've had no issues with valve seats in using unleaded fuel to fuel many of my vehicles for about 30 years, including about seven currently in hand that were originally designed for leaded fuel. Two of them are unmodified Continental and Lycoming aircraft engines that were STC'd for unleaded auto fuel about 25 years ago, and would be fine with it now except for alcohol now mandatory in my market.

I think 100UL will transition into the market when the oil companies figure out how and when they'd like to do it, and replace 100LL. Relatively complex, expensive Diesels will maintain their appeal in those areas where GA largely doesn't exist. But where GA is more widespread it makes more technical sense to use a more refined, higher performance fuel.

[westhawk]

Originally Posted by Big Pistons Forever

Jet A powered certified piston GA aircraft is IMO the only viable long term solution.

That's one possibility for the longer term future BPF. And I think more so for higher horsepower engines than for lower horsepower engines. Another possibility is that unleaded avgas may remove some of the perceived urgency to further develop diesel aero engines. The designs to date have had some marginal success, but they still need to be allot better to compete with gasoline engines. Particularly in the higher horsepower piston engine market, the development costs may not allow diesels to be competitive with gasoline engines from a cost versus performance standpoint for some time to come. Burning Jet fuel would have to become quite allot less expensive than it currently is compared to avgas. And some of the performance versus weight gap would have to be closed before market demand would warrant such an investment on the part of either manufacturers or customers.

Much may depend upon what happens to the price delta between jet and avgas in the future. Your guess is as good as mine! With GA being such a limited market, using jet fuel seems logical from a refining, distribution and economy of scale standpoint. Yet so far, any purported cost and performance advantage that has been achieved doesn't seem to have been significant enough to greatly affect aero engine market demand. With further development, who knows though?

westhawk

P.S: While it seems likely that 100UL will be somewhat more expensive to buy than 100LL, I don't see it being prohibitive. And as a "drop in" replacement for 100LL, things can continue as before. No more worry about how to run higher compression avgas engines on lower octane fuel.