An-124 Strategic Transport: News

Scorpius wrote:

It looks like a disc burst.

The plane belongs to Volga-Dnepr

Rodion_Romanovic wrote:

Scorpius wrote:

It looks like a disc burst.

It can be repaired and returned to service.

Rodion_Romanovic wrote:

Scorpius wrote:

It looks like a disc burst.

Bird ingestion :

And it caused that kind of damage?

Normally modern engines must ensure that they can safely shot down, even with a large bird ingestion...

Possibly the D18T was not designed to ensure this.

The pictures above do not correspond to the engine or plane in this case

Rodion_Romanovic wrote:And it caused that kind of damage?

Normally modern engines must ensure that they can safely shot down, even with a large bird ingestion...

Possibly the D18T was not designed to ensure this.

That's the case and this example proves it.

Russia should get cracking on the PD-35. Most of the work has been done already getting the PD-14 into production.

The D18T is a 23 ton max takeoff thrust engine so they will need a down scaled PD-35. But I have not heard of any
such thrust range option in the PD series. Maybe it is easier to upscale the PD-14.

LMFS wrote:The pictures above do not correspond to the engine or plane in this case

Yes, it looks like it. But the problem is the D18T is old and tired. It was made by Motor Sich so we are looking at excessively
long operational times. I doubt that these engines are less than 30 years old. They need to be retired ASAP.

kvs wrote:

Rodion_Romanovic wrote:And it caused that kind of damage?

Normally modern engines must ensure that they can safely shot down, even with a large bird ingestion...

Possibly the D18T was not designed to ensure this.

That's the case and this example proves it.

Russia should get cracking on the PD-35.  Most of the work has been done already getting the PD-14 into production.

The D18T is a 23 ton max takeoff thrust engine so they will need a down scaled PD-35.    But I have not heard of any
such thrust range option in the PD series.    Maybe it is easier to upscale the PD-14.  

Yes there were both the PD24 and PD28 among the planned engines, but it is not clear by when.

How I (and other people) posted in other threads, there is also the possibility of the NK23D, a high bypass derivative (with around 23 tons of thrust at max takeoff) of the NK32 (the engine of the Tu-160). Apparently an engine for the subsonic Pak-Da is being currently developed (also derived from the NK32). That could also be used as basis for the creation of a transport aircraft engine.

kvs wrote:Yes, it looks like it.   But the problem is the D18T is old and tired.   It was made by Motor Sich so we are looking at excessively
long operational times.    I doubt that these engines are less than 30 years old.   They need to be retired ASAP.

I don't know if it may affected this engine in particular, but I read not long ago about Motor Sich having reliability problems with the D18T. Russia in principle has already the capability to repair the engine, that is not as good as building complete engines and being able to substitute them but they will have to live with it for the time being.

Volga Dnepr has grounded the entire fleet until the engines are cleared by the manufacturer. With the situation between Russia and Ukraine is this even possible? I think this will pressure a global grounding of the fleet. Does any maint for the engines on the RUF or VD planes get done in Ukraine?

Motor Sich had problems with the D18T recently and then the VN accident occurred, result: Antonov Arilines has not grounded the fleet and the manufacturer says nothing about the failure. This is a politically motivated dishonest competition going full criminal and a further reason why Russia needs a replacement for the D18T and ultimately for the An-124, in short term actually.

LMFS wrote:Motor Sich had problems with the D18T recently and then the VN accident occurred, result: Antonov Arilines has not grounded the fleet and the manufacturer says nothing about the failure. This is a politically motivated dishonest competition going full criminal and a further reason why Russia needs a replacement for the D18T and ultimately for the An-124, in short term actually.

Were the D18T engines of VolgaDnepr overhauled by Motor sich or by Russia?

(if i am not mistaken Russian air force An124 are overhauled in Russia independently from Motor sich)

Rodion_Romanovic wrote:

LMFS wrote:Motor Sich had problems with the D18T recently and then the VN accident occurred, result: Antonov Arilines has not grounded the fleet and the manufacturer says nothing about the failure. This is a politically motivated dishonest competition going full criminal and a further reason why Russia needs a replacement for the D18T and ultimately for the An-124, in short term actually.

Were the D18T engines of VolgaDnepr overhauled by Motor sich or by Russia?

(if i am not mistaken Russian air force An124 are overhauled in Russia independently from Motor sich)

Overhauls are not new engines. So it does not automatically imply that the failure is due to an overhaul. These old engines need to be
retired ASAP whether they are overhauled or not.

kvs wrote:

Rodion_Romanovic wrote:

LMFS wrote:Motor Sich had problems with the D18T recently and then the VN accident occurred, result: Antonov Arilines has not grounded the fleet and the manufacturer says nothing about the failure. This is a politically motivated dishonest competition going full criminal and a further reason why Russia needs a replacement for the D18T and ultimately for the An-124, in short term actually.

Were the D18T engines of VolgaDnepr overhauled by Motor sich or by Russia?

(if i am not mistaken Russian air force An124 are overhauled in Russia independently from Motor sich)

Overhauls are not new engines.   So it does not automatically imply that the failure is due to an overhaul.   These old engines need to be
retired ASAP whether they are overhauled or not.  

Well that really depends on how many hours are on the engine. There is nothing about age that defines if an engine is beyond repair. There is a lot of sophisticated metallurgical testing that can be done. In this case the fan discs will all have to be tested for metal fatigue. Its is also possible and maybe even economic to manufacture new discs since there is about a 100 + engine fleet. If its just fatigue or manufacturing flaw then they will have to be inspected at intervals.

Rodion_Romanovic wrote:Were the D18T engines of VolgaDnepr overhauled by Motor sich or by Russia?

(if i am not mistaken Russian air force An124 are overhauled in Russia independently from Motor sich)

This may help:

Mr Vekshin said: “We need to hear from the Russian aviation authority, and from the manufacturer of the engines which we think is now overdue. We need to see the directives and the results of the investigation. We hope that process will start any day now.

“Once the directives are implemented, we can proceed, but it will take a significant time. We know what part failed, but there needs to be a very thorough investigation with special experts.

“Hopefully this will be a question of weeks, but it has to be as perfect as possible – so guesswork on timing is not good enough.”

Volga-Dnepr has some 60 AN-124 engines, all of which will need to be inspected in depth. They are manufactured and maintained by Ukraine’s Motor Sich, raising questions of whether any delays might be politically motivated.

https://theloadstar.com/exclusive-safety-first-as-volga-dnepr-grounds-its-an-124-fleet-indefinitely/

mnztr wrote:

kvs wrote:

Rodion_Romanovic wrote:

LMFS wrote:Motor Sich had problems with the D18T recently and then the VN accident occurred, result: Antonov Arilines has not grounded the fleet and the manufacturer says nothing about the failure. This is a politically motivated dishonest competition going full criminal and a further reason why Russia needs a replacement for the D18T and ultimately for the An-124, in short term actually.

Were the D18T engines of VolgaDnepr overhauled by Motor sich or by Russia?

(if i am not mistaken Russian air force An124 are overhauled in Russia independently from Motor sich)

Overhauls are not new engines.   So it does not automatically imply that the failure is due to an overhaul.   These old engines need to be
retired ASAP whether they are overhauled or not.  

Well that really depends on how many hours are on the engine. There is nothing about age that defines if an engine is beyond repair. There is a lot of sophisticated metallurgical testing that can be done. In this case the fan discs will all have to be tested for metal fatigue. Its is also possible and maybe even economic to manufacture new discs since there is about a 100 + engine fleet. If its just fatigue or manufacturing flaw then they will have to be inspected at intervals.  

The engine manufacturer tests the discs (from Fan, compressors and turbines) during the development of the engine. Then there are calculations based on the stresses that the various features of the disc will have in service to clear a certain fatigue life. The feature (or subpart) of the disc with the shorter life is the "life limiting".

In addition the engine manufacturer has to ensure that even if small manufacturing flaws (small enough that current techniques cannot reveal its existence) are present inside the disc, they will not evolve into a dangerous crack big enough to menace the integrity of the disc itself before the disc is removed from service.
These calculations must also be approved from the air worthiness authority (FAA in the US or EASA in Europe).


The life so cleared is a hard limit. Turbine and compressor (including fan)  discs are critical parts.

The inspections you mention would instead exist to check for  service induced defects (e.g due to poor handling  by the mechanics)

While other parts of the engine may remain in service until they do not present damage (or maybe are removed due to performance loss), no disc can be in service more than that limit so calculated.  The manufacturer could however later be able to clear a longer life via additional development testing, or via more precise calculations (if there are uncertainties you always have to consider the worst possible condition).

The rules were made much more strict in the 80s, after several dangerous accidents happened due to disc failures


So this means that it is not possible that the airplanes are flying with discs too old. Each disc is tracked and must have a full available history, so that it is removed from the engine before the limit. Should this history be not clear or incomplete the disc is scrapped.

An airline discovered flying with a disc which exceeded its declared safety life would be blacklisted, forbidden flight operations and the people involved would face criminal prosecution.

Failures of other parts could also cause disc failure,  but in that case there should be other ways of preventing it.

Just to clarify, normally overhauling an engine will also restore some performances and improve fuel consumption in comparison to a deteriorated engine,  but this is due to wear in other parts of the engine (which could be then repaired or replaced).  Discs MUST be in pristine conditions when they are removed from service due to reaching their life limit.


A properly overhauled engine (even if it was firstly manufactured 40 years ago) must be safe, otherwise somebody is doing a criminal act.

https://korrespondent.net/world/russia/4299859-v-rf-ustanovyly-prychynu-avaryy-samoleta-ruslan

Antonov Airlines has instead decided that they'll keep flying...

https://theloadstar.com/well-carry-on-flying-says-antonov-despite-volga-dnepr-an-124-engine-worries/

If overhauls made engines new, then there would be no need to ever retire them. All of these certifications do not
make the fact that an old engine is being refurbished go away. The only way to fully remove stress failure modes
(e.g. microfractures and loss of tempering through many heating cycles) is to replace the engine with all new parts.

I can see the same excessive concern being applied here as with any accident for Roscosmos. The sky is always falling
for Russia but any accidents and failures in the west are just incidentals.

Rodion_Romanovic wrote:Antonov Airlines has instead decided that they'll keep flying...

https://theloadstar.com/well-carry-on-flying-says-antonov-despite-volga-dnepr-an-124-engine-worries/

No effort of any real inquiry in that article. Since Banderastan is now a vassal of NATzO it gets a pass. If
we had the engines being manufactured in Russia this reporter would be sure to let his readers know all
about lack of reliability and corruption.

Yes every engine has its overhaul limit. But even within that incidents happen from time to time. I highly doubt this engine was beyond the limit as Volga Dnper needs to fly its plane everywhere and cannot survive a blacklisting.

I doubt there is anything they cannot develop a fix for in that wing box. my guess is they will fix it. No spoilers and only emrg breaks and I ready it has 83T of cargo on board. So well done!!!