Welcome to Flight Global Focus, your essential podcast for
trusted aviation insight. I'm US Aerospace Managing Editor
John Hemmerdinger, and this week we're looking at some recent
propulsion sector developments in different parts of the globe,
Europe, Russia and right here in the USA.
These developments involve some familiar but also some less
familiar power plants and a mix of conventional and
unconventional technologies. With me is European Aerospace
editor Dominic Perry, who has been learning about Rolls Royce
exploration of hydrogen power. Hello, Dominic.
John, glad to be here. Yeah, Thank you for being here.
I also have with me Air Transport Editor David Kaminsky
Morrow. And he has an update about
starting us off with some Russian power plants, progress
that's being made with a domestic engine programme there
that David's been covering. David, why don't you tell us
about that? Hello John.
The situation in Russia has obviously been very difficult
with the country's aerospace industry labouring under
international sanctions, but there it does seem to have been
some progress in the last couple of weeks.
The Avid Vigatel PD8, which is part of the family of engines.
The PD is a Russian abbreviation for prospective engine and the
number 8 signifies the 8 tonne 8000 kilogramme thrust level.
That engine's been developed for the Yakovlev SJ100, which is an
import substituted version of the Superjet 100 with some of
its all of its foreign systems replaced by domestic ones.
And that includes replacing the previous Franco Russian Sam 146
engines and United Engine Corporation, which is which is
developing. That power plant has just
completed certification testing for the PD8, which has been
flown on various SJ100 prototypes as as well as the
Elysian 76 test bed and it's spent about 1400 hours airborne
PD eights. It's brought in some new
technologies like materials for turboline blades, which offer
greater resistance to high temperatures.
And it's been undergoing the kind of kind of demanding tests
that you'd expect for for engine development.
So icing and bird strike the blade out, test water ingestion,
hail ingestion and so on and so on.
With all that completed, it's now a matter of submitting the
documents to Rosaviazia, which is the Russian Federal Oversight
Authority, and waiting for a certification decision.
That's a significant step because Russia's planning to use
the PD8 not only for the SJ 100, but also for a RE engineering
programme on the amphibious area of 200 firefighting aircraft.
Yeah, David, the PD 8, that's a family of engines and a larger
version is pretty critical to Russia's main civil airline
project. Do I have that right?
How's that going? Well, yes, the, the, the PD 8 is
like the younger brother, if you like of the, of the PD 14, which
is the medium sized version. And that engine's designed for
the MC21 narrow body, which is kind of Russia's answer to the
to the A320. Yeah, the engine was originally
intended as an optional alternative to the Pratt and
Whitney geared turbofan, the PW 1400 G, but sanctions have
obviously put the kibosh on that plan.
The PD 14's already been certified, but because of the
sanction situation, the MC21 programme has had to undergo its
own import substitution effort and that's delayed entry into
service. So although the MC21 first flew
with the PD14 engines back in December 2020, the airframe and
engine combination still hasn't achieved certification.
Only about 1/3 of the certification flights have been
completed. And that's according to the head
of state technology firm Rostek, Sergei Chernozov, who's who's
just had the unenviable task of telling the Russian President
Vladimir Putin that the MC21 certification has been pushed
back again to next year. Incidentally, he also mentioned
that the SJ 100 is about 80% of the way through it's
certification flights and they're still aiming for
certification this year. Yeah, David, interesting it.
It seems a bit premature to talk about the future when these
engines are not certified yet, at least not with the aircraft
that they're going to be powering.
But are there any other developments in the pipeline
coming out of Russia, engine developments?
Yeah. Well, I think the, I think the
most notable future programme is kind of the big belly goat
graph, if you like, of the PD family, which is the PD-35.
And that's a proposed high thrust variant.
And that would be quite a substantial development for the
domestic civil engine industry because even though Russia has
built wide body aircraft like the Ilish in 86 and 96, it's not
really built an equivalent to the engines that you'd find on
the big Boeing and Airbus wide body twins.
There's been work on technology and core demonstrators for the
PD-35, but the engine at the moment is really a solution
looking for a problem. There's no specific application
for it. The proposed COMAC C929, which
is like a Chinese 777 if you like, had been a possibility but
that seems to have faded now that the C929 is becoming very
much a Chinese driven project rather than the original Russian
Chinese partnership. The other prospect is an engine
that's called the PD 26 and that emerged as a potential power
plant last year when United Aircraft drew up initial
proposals for a twin engine wide body family around the size of
Boeing 787. Thanks David.
I had mentioned at the top of the programme that Rolls Royce
it's experiments with hydrogen fuel and Dominic has been
looking into that lately. I believe there was a, a test
recently. Dom what?
What can you tell us? Yeah, that's right.
So Rolls Royce has been looking at the potential of hydrogen
combustion since about 2021, probably before that.
But this is the the latest, latest set of projects in the
research and innovation space. And this latest ground run was
really the culmination of that effort.
So how many engines has Rolls Royce run on hydrogen?
Do we know? Yeah, I mean it is just three or
although you could look at it the other way around and
actually it's run three, which is a great achievement.
So the first of those was an AE 2100, which is the engine that
powers the C130 aircraft, the Lockheed Martin transport.
Oddly enough that that engine has a an interesting history of
that particular engine in that it was used prior to these tests
for an I'll fated programme called EFAN X which was going to
be run with Airbus before it got cancelled.
So it's nice they they have found a decent use for it.
Anyway. They ran that particular engine
in 2022 at Boscombe Down in the UK.
It was relatively rudimentary, so the engine itself was
obviously as sophisticated as it gets, but a lot of the equipment
around it, the fuel system for example, was more an industrial
rather than aerospace grade. So that should be seen as a
concept demonstrator. Can we run an engine on hydro?
Can we run a modern engine on hydrogen?
So with that out of the way, this was followed by a Pearl 15.
It was tested in Darwitz in Germany where it's built.
So the Pearl 15 is business jet engine and they wanted to test
the non propulsive functions that normally run on kerosene or
jet fuel, cooling the oil system, moving hydraulic
components, that sort of thing in order to check that that
would still work without any kerosene in the system so that
there was no hidden fuel tank that was secreted away somewhere
in the engine. And the last engine is another
Pearl 15, which this time was run at NASA's test site in
Stennis in Mississippi, which incorporate a lot of the
learnings and the modifications from those earlier tests.
What kind of modifications are we talking?
About they are mostly to the combustion system, the fuel
nozzles and the combustor can as they put it.
It's almost a cliche, but everyone knows that hydrogen
burns very readily. I mean think Hindenburg clearly,
but it also burns in a different way to jet.
So the flame speed, how fast that flame spreads, is much
quicker. So a lot of the testing was
about how you control the combustion process, not simply
answering the question, can we burn hydrogen?
Because the answer is clearly yes.
Right. And and how long did the test
last? So.
The test of that particular engine, the runtime, was
actually a few 10s of hours as Rolls Royce put it.
But that doesn't really account for the multiple rig tests and
other research. It's run in the UK and elsewhere
simply to get to that point. So it was very much backed by
all that research. So I think when they came to run
the engine, they they were fairly confident that it would
behave in the way that they expected.
And the feedback from Rolls Royce was very much, it did do
that. It behaved just as the forecast
predicted, Yeah. I wonder what this means in
terms of a potential launch of a new engine, a hydrogen engine by
Rolls Royce? Does this bring them closer it?
Brings them closer, but I don't think they are sufficiently
close that they could do it now. Roles is carrying out a lot of a
lot more research to optimise the combustion system and other
parts of the engine to account for the differences between
hydrogen and jet fuel. And there are other technologies
that need to be developed or adapted, changing the coatings
and components to increase their durability in that hydrogen
environment. It's also worth pointing out
there's no demand yet for such an engine.
The wider infrastructure investment, green hydrogen
production and distribution still hasn't really kicked off
and there remains a question mark about whether it can be
used, or maybe rephrase that, if it will be used as a future
aviation fuel. So the best way to to view Rolls
Royce's efforts is that it's preparing for the future, if
that's the direction the airframers decide to go.
Dom, let me ask you this. Would we know or do we know if
this is a technology or power plant that might be on something
like Airbus had talked about their hydrogen?
What? What was it called?
E You'll know the name 0. E Is there 0?
E So is it? Is it is that still on life
support? Well. 0 E is progressing.
Not as quickly as it was, very much with the slower than
expected infrastructure development in mind.
But the first 0 E aircraft won't use hydrogen combustion.
Airbus thinks it will use hydrogen fuel cells.
So Rolls Royce's research, which while beautifully illiterative,
is useful. Don't expect to see that
technology in service before let's say 2045, probably later.
Right. All very interesting and it
brings me to GE. Of course GE has a number of
next generation technologies that they've been working on.
They've looked at hydrogen also, but they're, they're also
working on some other things like the open rotor.
But I was at GE in Cincinnati this week and they, they held a
press conference. It was actually in their
Evendale facility, which is just outside Cincinnati, but it's a
big leap centre development centre and a testing centre.
And we had a tour of the facility and spoke to some of
their executives and they weren't discussing too much of
the next generation stuff, but they were talking a lot about
LEAP and that's the engine for A320 Neos and for 737 Max, the
GE and Safran produce under the CFM partnership.
The focus really was the durability issues.
Now we've all heard about the durability problems affecting
next generation engines and and leaps have been affected.
Of course, Pratt and Whitney's GTF has been affected
potentially, arguably much to A to a larger degree.
But what we have had is blade degradation and this comes
primarily in regions that are hot and dusty.
Those are the Middle East. They can be some places in India
or Asia. And GE has been introducing some
durability improvements that they say are really actually now
taking hold. The dust issue is interesting
because GE and the others have been dealing with dust problems,
of course for years. And they made the point that the
GE 90, which is several generations ago had some
durability issues in the very beginning of the programme.
And, and then GE came out with the GENX and that had some
significant dust ingestion durability problems when it was
first introduced. Now GE they're making a point of
stressing that they've done all this dust ingestion tests, which
is where they have a turbofan in a test cell and they have these
in Evendale, Ohio. And they they have developed a
dust that mimics what's found in the Middle East, is self
developed by GE and they injected into the engine and
they see how the engine performs.
Now those tests are ongoing, but GE does know that these types of
tests have have really led to significant improvements in
their wide body engines, particularly the GE and X.
And what it's allowed to do is that they can develop new parts
that allow the engines to go much longer between required
removal from wing and maintenance overhauls.
But clearly a wide the body engine isn't quite the same as a
narrow body engine. How does that work?
Tie into the reliability improvements plan for the leap,
Yeah. The leap is it's ongoing.
The problem happens because this dust gets sucked into the low
rather the high pressure turbine.
And the temperatures in there can cause the components to
degrade, especially when susceptible to dust.
Now these engines have what engineers called cooling pads.
And this is colder air that's within the turbine that is
supposed to cool the blades and the other components to a
temperature at which they will not melt or not degrade.
But those cooling pads are incredibly complex and when
they're not exactly perfectly right, that's when you get the
blade problems. G ES point is that all the
testing they did on the GENX and the testing that they're now
doing on the leaps, the dust testing has given them what they
described as a a complete or nearly complete understanding of
what's happening within the engines.
One of the their head of technology said that they have
cracked the code in understanding what happens and
we're dealing with tolerances that are minuscule, the width of
a human hair and how they direct these cooling paths with with
the geometry of the blades and the holes in the blades.
So they are saying that Leap durability is improving.
Their head of commercial aircraft engines, Muhammad Ali
says that the Leap 1A, that's the A320 version, A320 Neo.
He says that engine, that engines durability is now on par
with where CFM 56 was when the CFM 56 was in its first few
years of service. And he says that the Leap will
meet the CFM 56's ultimate durability record.
Now that engine, the CFM 56 is sort of a standard setter,
standard bearer. It is known for incredible
reliability. I've had airline CE OS tell me
that the new generation engines will will simply never be as
reliable as the CFM 56. The pressures are too high, the
temperatures are too high, which of course improve fuel
efficiency, but those high temperatures and pressures also
cause parts to degrade. GE is saying that's not the
case. They say give us time, wait and
see and be patient and your engines will have that same
level that's. Interesting.
I had an airline chief executive tell me once that the industry
had been spoilt by the CF 756, that it was too good, and that
anything following it was all automatically doomed to to come
in to be judged as a lesser engine against that one.
Wasn't there also an issue with cooking on fuel nozzles of the
Leap engines? That's right.
Cooking and this issue has been ongoing for several years.
And when the engines are shut down, there is still some level
of or some amount of fuel either in the nozzles or around the
fuel nozzles in the combustor. And the residual latent heat
within the engine causes that fuel to evaporate.
And what's left is coke and it can coat the nozzles.
And there were several instances in which LEAP engines on a 321
Neos had suffered power reductions, unanticipated
uncommanded power reductions several years, I think it was in
20, I think it was in last year. And so this has proved to be a
problem. Now fixing this problem requires
replacing the fuel nozzles at intervals that we don't exactly
know, but that seem to be fairly frequent if not very frequent.
And to fix it, you do not need to remove the engine from the
wing, but it does require that operators take the engines out
of service for several days to to perform to perform the work.
GE in 2024 released a what they described as a fix or at least
just something that helps address the problem.
It's called a reverse bleed system and it's been described
as me as a a high tech fan that blows colder air back into the
engine after shutdown and hence addresses the problem of fuel
evaporation or minimises the fuel evaporation, minimises the
cooking. That same reverse bleed system
is now in development and nearly complete for the Leap 1B, which
powers the 737 Max. And apparently this year it's
going to be rolled out for the Leap 1B.
So good news for Leap operators then.
One of the interesting things that GE and Saffron are working
on through CFM is obviously the RISE Open Rota programme.
Was there any mention of that during your visit?
Yeah. Curiously, there was, I think no
mention of it at all. And during previous visits to GE
in recent years, that's been the focus.
Now why there was no mention of it, I don't know.
It could be that GE is is focusing or choosing to focus
and choosing to stress durability.
And in fact they they said that word about 100 times during the
visit. So they clearly want operators
to be happy with with what's out there now, which makes sense
because there has been a mood among some customers that GE and
Pratt and Whitney also better fix the current problems before
they start talking to us about future technology.
So that could be it. The rise, of course, has been
top of mind for GE otherwise. And as an open rotor, they say
it'll be something like 20% more efficient.
They've been working with Saffron and developing
demonstrators, and technology is still several years away from.
And we're talking twenty 30s for introduction on the next
generation narrow body if it happens, which is a big question
mark. So it is possible now that GE is
saving some rise news for the upcoming Farnborough Air Show or
maybe we won't hear much about it then we don't know.
But Farnborough would be the time.
So we will keep an eye out for it.
Great. Thank you, John.
Thank you, Dom, and thank you David.
Also, pleasure. John, thanks very much.
And that's it for us. You've been listening to Flight
Global Focus, which is a production of Flight Global with
editing by Lucy Johnson. If you want to get in touch with
us or for commercial opportunities related to the
podcast, please e-mail podcast at flightglobal.com.
Listen, rate, review and subscribe wherever you get your
podcast. I'm John Hemmerdinger for Flight
Global Focus. Join us next week for more in
depth analysis covering the latest developments in airlines,
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