Latest UL91/94/100 approval status for US-registered DA40s

[linzhiming]

I am facing a situation with one airport in Europe which I wanted to visit and has now imposed restrictions on aircraft using 100LL so that has got me thinking about the status of unleaded fuel approval for US-registered DA40s. In this case it is not about fuel offered at the airport (i.e. not like the situation at some airports in California) but flying with an aircraft using 100LL - ironically, the only Avgas fuel that the airport offers is 100LL.

AFAIK, the status for EASA-registered aircraft is that there is fleetwide authorisation of the aircraft/airframe as long as the engine manufacturer has approved the use of UL91 (see https://www.easa.europa.eu/en/faq/19380). So this solves the issue for EASA-registered DA40s.

For US-registered aircraft, FAA fleetwide authorisation continues to be pending. So what options would be available? Looking through the FAA's STC database, it looks like Petersen Aviation has an STC for DA40s to allow UL91, Swift Fules has one to allow UL94, and then there is GAMI with an STC to allow G100UL.

Curiously, the airport is looking only at the aircraft's certificate and fuel capabilities (presumably, they don't want to be in the business of taking fuel samples at this point), so for now an updated certification basis is what is needed.

And my home airfield actually offers UL91 at the same price as 100LL so the Petersen Aviation certificate is actually attractive - does anyone have experience with operating DA40s with UL91?

Does anyone know what the status of the planned FAA fleetwide authorisation is for UL91? (https://www.avweb.com/aviation-news/faa ... ton-fleet/)

[astaib]

Hi,

Not sure that my comment will help, but I'm always asking myself how we will do after 2030 in Europe when the 100LL will not be available anymore.

The IO360 M1A allows the use of MOGAS 98, but I was told that the plane itself is not certified for the use of that kind of fuel.
Do any of you know if there is something in the pipes on Diamond side on this topic?

Will our planes be grounded on 01/01/2030? Will be have to retrofit them with an other engine?

Arnaud.

[linzhiming]

The IO360 M1A allows the use of MOGAS 98, but I was told that the plane itself is not certified for the use of that kind of fuel.

Per the Lycoming SI 1070 (https://www.lycoming.com/service-instruction-no-1070-AB), the IO-360-M1A is allowed to use UL91. And if you operate an EASA-registered aircraft, the EASA standard change means that the aircraft/airframe is certified for it as well. See https://www.easa.europa.eu/en/faq/19380

So EASA-registered aircraft owners wouldn't need to worry. But I am/was worried about US-registered aircraft owners in Europe if there is no fleetwide UL91 authorisation for DA40s although it seems that Petersen Aviation have an STC for UL91 (see https://drs.faa.gov/browse/excelExterna ... 3A815.0001).

So I am therefore curious about DA40 owner experiences operating DA40s with UL91.

[astaib]

Hi,

This is for UL91, but what for MOGAS (98 I suppose) ?

I'm based in France and we have a very limited fueling station with UL91...

Arnaud.

[linzhiming]

This is for UL91, but what for MOGAS (98 I suppose) ?

It should be approved for EN228 MoGas as well, see page 5 of that Lycoming SI and pages 48/49 of the EASA standard change document.

Whether it is a good idea for long-term ongoing use, I don't know (same question that is being asked about G100UL).

[astaib]

Hi,

Yes, I read the SI but I also read this in the SI and I'm a bit confused about how to find these information with fuel at "car pump station":

Automotive ground transportation fuels available direct to consumers (e.g. “pump gas”) usually do not
have labels with sufficient information to identify compliance with the requirements in Table 2. While
indicated octane is generally necessary for display at retail points of sale, octane rating methods, fuel vapor
pressure and oxygenate content can vary widely and are generally known only at the wholesale terminal.

Arnaud.

[linzhiming]

Yes, I think that refers to people running to get fuel from an outside normal gas station for cars though. And gas stations for cars in Western Europe normally clearly show the specifications as well. The key point here is about not using fuel that contains ethanol, e.g. E10.

Not sure about airports in France but I know from airports in Germany that they obtain MoGas from wholesale/reputable sources (they call it "Super Plus Aviation").

And if 100LL is really being significantly curtailed in Europe, I believe UL91 is commercially produced by manufacturers, including Total (see https://aviation.totalenergies.com/en/f ... avgas-ul91). I have been to more and more airfields recently that offer UL91.

Without being an expert in this field and just following news on this topic over the last 10-15 years, a UL91 drop-in replacement for 100LL for low-compression engine aircraft hasn't been the challenge but it has been to find a suitable drop-in replacement for 100LL for high-compression engine aircraft (e.g. SR22).

[linzhiming]

@astaib, it also looks like Total could offer "UL AERO SUPER +" (https://aviation.totalenergies.com/en/b ... ation-fuel).

For our American friends waking up to this conversation, it would be good to understand:

- Does anyone have experience with the Petersen Aviation STC certificate for UL91 use in N-registered DA40s? (https://drs.faa.gov/browse/excelExterna ... 3A815.0001)
- What is the status of the planned FAA fleetwide authorisation for UL91? (https://www.avweb.com/aviation-news/faa ... ton-fleet/)
- Has anyone had any negative experiences with using UL91 on DA40s on an ongoing basis?

[linzhiming]

Bumping this up

Any takers regarding the questions?

Thanks!

[TimS]

I figure a little clarity on the fuels might help.
Europe autogas uses RON (research octane number) to measure octane.
The USA we use AKI (anti-knox index).
A descent rule of thumb is RON * .95 = AKI. So EU Autogas 98 is roughly US 93 auto gas.

Not a Diamond, but there is a local flight school near me (ok, about an hour drive outside rush hour) which uses 91 Octane on their C172s for the flight school. Not only is the gas cheaper, but they previously told me the run almost double the number of hours between oil changes because there is no lead, and an early tear down overhaul is around 3000 hours.

e.g. There is a lot of evidence that the TEL in avgas is bad for the engine (just look at Rotax manuals for another example). As long as the engine does not need the higher levels of octane, I would prefer to run an almost any unleaded fuel.

Tim