I have been very impressed by aircraft engines. Relatively small in size vs the aircraft and the loads they bring up in the air. Steadily more efficient and silent also. I understand that the relative value of the engines vs the whole aircraft is very high (how much by the way ?), which explains why many of such engines can be used on several aircraft during their life.

All in all, what are the life expactation statistics for aircraft engines on average (years, hours, cycles, aircraft carried, etc) ?

Mods may want to edit the title to include "engines".

Interesting question robby31. I'd like to know too.

A lot of the time it seems that when aircraft are scrapped, the engines are removed and live on. Are these engines usually as old as the aircraft itself or were the engines replaced at some point in the aircraft's life making the engines younger and still fit for use on other aircraft?

Engines are mere assemblies of parts on a fixed chassis. The chassis can last forever as long as you keep replacing whatever needs to be replaced inside the engine.
Few engine parts last an aircraft's lifetime, they would be swapped several times so if you consider that, an aircraft would go through several engines during a lifecycle even though thr engine keeps its serial number.

Engines are lifed in hours. They last rough;y 10,000 hours before a deep strip and inspection. Parts are cleaned, inspected and replaced. They are then sent back to the airline or lease agent rated at zero hours. I believe RR did a long life test on an engine with Icelandair which reached about 17,000 hrs.

Engines are removed from aircraft for varying reasons. In general, engines are an "on-condition" assembly so as long as they continue to pass the regularly scheduled inspections (borescope, chip detector etc) they continue to fly. Engines may also be removed for expiration of life-limited-parts (LLPs) which are generally the rotating internals that are cycle limited and are generally "throw-away" parts. Engines may also be removed and reinstalled on another aircraft for "stagger" so the carrier can pair a low time engine with a higher time engine to avoid having an airframe with two very high-time engines on it. I've seen CFM-56 engines easily last 5 years in service and Pratt 2000s seem to be a bit less, say 2-4 years on average. Every engine is different though and there is generally no defined life limit on them other than what the LLP limits require.

The newer engines don’t last as long between overhaul. Higher core temperatures and pressure help with efficiency but can increase wear. There have been CFM56 engines make it to 40,000 hours (10 or more years of service) although that is an anomaly. I doubt we will ever get another engine last as long on wing between overhaul as CFM56 since there is increasing demand on efficiency.

Engines have cycle and based on condition hour limits between overhaul. A PW4090 only goes 1300 cycles between overhauls (why Pratt lost favor on 777). A LEAP-1A is intended and will eventually set the record at 30,000 cycles to first overhaul, 15,000 to 2nd and is to be scrapped with the A320 at 60,000 (or sold). Most narrowbody engines are goid for 20,000 cycles to first overhaul. The CF-34-10 had issues (since fixed) that reduced time on wing. Most widebody engines are good for 4,000 cycles on wing, which is why they are pulled on condition, the hours erode parts.

It was correctly noted engine parts are replaced (often rebuilt) so the end of life engine. Some JT9Ds were used so long they needed new casings, so the engine at the end had no parts left from delivery.

Lightsaber

I think they try and avoid having both/all engines being the same 'age' in hours on an aircraft. So a new aircraft might have one of it's brand new engines replaced with a slightly older one, so you have a brand new and a used engine on the aircraft.

Something to do with trying to avoid the risk of both engines running into problems at the same time.

BlueberryWheats wrote:

I think they try and avoid having both/all engines being the same 'age' in hours on an aircraft. So a new aircraft might have one of it's brand new engines replaced with a slightly older one, so you have a brand new and a used engine on the aircraft.

Something to do with trying to avoid the risk of both engines running into problems at the same time.

Not at any civilized airline and those that do probably also ban a fleet type from their country after one is involved in an accident. An airline is free to do whatever they please after delivery but modern engines are so reliable and the quality control is good enough that there is no reason to do this.

Wacker1000 wrote:

BlueberryWheats wrote:

I think they try and avoid having both/all engines being the same 'age' in hours on an aircraft. So a new aircraft might have one of it's brand new engines replaced with a slightly older one, so you have a brand new and a used engine on the aircraft.

Something to do with trying to avoid the risk of both engines running into problems at the same time.

Not at any civilized airline and those that do probably also ban a fleet type from their country after one is involved in an accident. An airline is free to do whatever they please after delivery but modern engines are so reliable and the quality control is good enough that there is no reason to do this.

Such as Trent 1000 and PW1100G ?

Wacker1000 wrote:

BlueberryWheats wrote:

I think they try and avoid having both/all engines being the same 'age' in hours on an aircraft. So a new aircraft might have one of it's brand new engines replaced with a slightly older one, so you have a brand new and a used engine on the aircraft.

Something to do with trying to avoid the risk of both engines running into problems at the same time.

Not at any civilized airline and those that do probably also ban a fleet type from their country after one is involved in an accident. An airline is free to do whatever they please after delivery but modern engines are so reliable and the quality control is good enough that there is no reason to do this.

Staggering of engines is a common practice worldwide at reputable carriers who have excellent safety records. Often times, a stagger is done to better manage the remaining hours or cycles on a particular engine and is a part of the overall engine management program.

There is also staggering between bigger and smaller versions, for example between A319 and A321. Engine which lost EGT margin on A321 could still have some on A319 as required power is much lower. An CFM 56-5B on an A319 can have 30000+ flight hours between overhaul but on A321 just 20000.

B757Forever wrote:

Wacker1000 wrote:

BlueberryWheats wrote:

I think they try and avoid having both/all engines being the same 'age' in hours on an aircraft. So a new aircraft might have one of it's brand new engines replaced with a slightly older one, so you have a brand new and a used engine on the aircraft.

Something to do with trying to avoid the risk of both engines running into problems at the same time.

Not at any civilized airline and those that do probably also ban a fleet type from their country after one is involved in an accident. An airline is free to do whatever they please after delivery but modern engines are so reliable and the quality control is good enough that there is no reason to do this.

Staggering of engines is a common practice worldwide at reputable carriers who have excellent safety records. Often times, a stagger is done to better manage the remaining hours or cycles on a particular engine and is a part of the overall engine management program.

Those aren't exactly the same. That is usually also tied to a derate program so it isn't purely putting an older engine on an aircraft in place of a newer engine - it is putting an older engine with less margin on a lighter aircraft so its removal is due to time and not performance.

At US Airways we had a CF6 that had five years on wing time on a 767 which is unusual.

B757Forever wrote:

Wacker1000 wrote:

BlueberryWheats wrote:

I think they try and avoid having both/all engines being the same 'age' in hours on an aircraft. So a new aircraft might have one of it's brand new engines replaced with a slightly older one, so you have a brand new and a used engine on the aircraft.

Something to do with trying to avoid the risk of both engines running into problems at the same time.

Not at any civilized airline and those that do probably also ban a fleet type from their country after one is involved in an accident. An airline is free to do whatever they please after delivery but modern engines are so reliable and the quality control is good enough that there is no reason to do this.

Staggering of engines is a common practice worldwide at reputable carriers who have excellent safety records. Often times, a stagger is done to better manage the remaining hours or cycles on a particular engine and is a part of the overall engine management program.

One of the advantages of unbundling air frame and engine supply, is the operator has more flexibility with engine deployment, even if leased.

You would think that where air frame and engines are leased from the same lessor, staggering is less likely, as at EOL, one engine swap (or more) may be required. However, there are internationally agreed clauses and formulae to compensate based on engine hours, cycles and maintenance, though some lessors are pedantic and require return of a matching set.

When US filed bankruptcy the first time we had massive engine changes as the original engines had to be mated on all the leased airplanes that were given back or had the potential of being taken.

Engines can basically be overhauled as long as the Parts can be repaired or manufactured. I would invite any of you to try and book a tour of the United Airlines Turbine shop at San Francisco to see what the repair capabilities are in Jet engine repair and overhaul. I can assure you? You'd be amazed and impressed as I am whenever I go there. I used to come to work early just to walk through there as they had so much neat stuff going on there. In my 33 years working the Line at United that was the one place I regretted not ever having worked, Those guys are craftsmen at their finest, Though My specialty was working Live Airplanes and I have put my name on enough releases to estimate that could have a Billion revenue passenger miles flown on my signature alone with all the Maintenance releases I've put my name on without ever a mishap. I joked before that I was never afraid to take an airplane out of service as I was FAR more afraid of the FAA than I was of anybody at United.

Up yo a year ago, British Airways operated B767-300 and B747-400, both fitted with the same RB211-524G/H. Engines could be swapped between fleets with a one hour mod to a couple of sensors that were fitted to the ETOPS B767 but not the B744. Engines were planned so that the ETIOPS B767 generally had the better engines, and the older engines ended up on the B744, which could withstand an engine failure with much less consequence.

Tristarsteve wrote:

Up yo a year ago, British Airways operated B767-300 and B747-400, both fitted with the same RB211-524G/H. Engines could be swapped between fleets with a one hour mod to a couple of sensors that were fitted to the ETOPS B767 but not the B744. Engines were planned so that the ETIOPS B767 generally had the better engines, and the older engines ended up on the B744, which could withstand an engine failure with much less consequence.

If I remember correctly the United 767-300ERs and the 747-400 had the same Pratt engines and could be swapped too.

Aircraft engines are the classic "George Washington Axe". That axe he used to chop down the cherry tree. The handle broke so it was replaced. Years later the blade broke so it was replaced, but is still the same axe. So goes the modern jet engine. The only part of the engine that can not be replaced is the Data plate. Technically that can be replaced, but the old damaged one must be surrendered to the engine manufacturer to get a replacement.

In essence a jet engine can live as long as you can keep replacing worn out parts with serviceable ones. In theory you can do the same for the entire aircraft, but It only usually happens in rare warbirds or when the military 'rebuilds' a old fleet like the P3.

Dalmd88 wrote:

Aircraft engines are the classic "George Washington Axe". That axe he used to chop down the cherry tree. The handle broke so it was replaced. Years later the blade broke so it was replaced, but is still the same axe. So goes the modern jet engine. The only part of the engine that can not be replaced is the Data plate. Technically that can be replaced, but the old damaged one must be surrendered to the engine manufacturer to get a replacement.

In essence a jet engine can live as long as you can keep replacing worn out parts with serviceable ones. In theory you can do the same for the entire aircraft, but It only usually happens in rare warbirds or when the military 'rebuilds' a old fleet like the P3.

There are houses like that too in some US cities.

In order to not be “new” you keep one wall and tear down the rest. Two years later the other wall can be torn down and the house expanded more. In the eyes of the city it’s not a new house (they all of it now meets current codes).

Dalmd88 wrote:

Aircraft engines are the classic "George Washington Axe". That axe he used to chop down the cherry tree. The handle broke so it was replaced. Years later the blade broke so it was replaced, but is still the same axe. ..

Well, a couple of thousand years before Washington and his axe, the classic thought experiment https://en.wikipedia.org/wiki/Ship_of_Theseus was debated. That's probably a much more "classic" way to describe the paradox of continuously updated complex object.

Phoenix757767 wrote:

At US Airways we had a CF6 that had five years on wing time on a 767 which is unusual.

I'm guessing you mean unusually long..?

Dalmd88 wrote:

Aircraft engines are the classic "George Washington Axe". That axe he used to chop down the cherry tree. The handle broke so it was replaced. Years later the blade broke so it was replaced, but is still the same axe.

Epitomized in Only Fools and Horses:
https://www.youtube.com/watch?v=56yN2zHtofM

At Continental we used the CF6-50 on the A300 and DC10

High time engines and or those starting to lose margins were rotated off the Airbus twin and installed on the Douglas tri jet that had more redundancy

Phosphorus wrote:

Dalmd88 wrote:

Aircraft engines are the classic "George Washington Axe". That axe he used to chop down the cherry tree. The handle broke so it was replaced. Years later the blade broke so it was replaced, but is still the same axe. ..

Well, a couple of thousand years before Washington and his axe, the classic thought experiment https://en.wikipedia.org/wiki/Ship_of_Theseus was debated. That's probably a much more "classic" way to describe the paradox of continuously updated complex object.

I'm 44 years old now. Have I been the same person with 20 years?

Sokes wrote:

Phosphorus wrote:

Dalmd88 wrote:

Aircraft engines are the classic "George Washington Axe". That axe he used to chop down the cherry tree. The handle broke so it was replaced. Years later the blade broke so it was replaced, but is still the same axe. ..

Well, a couple of thousand years before Washington and his axe, the classic thought experiment https://en.wikipedia.org/wiki/Ship_of_Theseus was debated. That's probably a much more "classic" way to describe the paradox of continuously updated complex object.

I'm 44 years old now. Have I been the same person with 20 years?

Well, if we are into philosophy, your question corresponds to the maxim "You could not step twice into the same river." Debates since time of Heraclitus.

Ship of Theseus is more specific and actually more fun. Because besides a gradual full repair of an existing ship with full new set of planks -- so that ship contains no original elements; it also includes warehousing all the original material, inventing a technology to fix them, and assembling a second ship out of original elements.
Obviously, there's no set of spare parts of "you", to build a second set of "you" to run a comparison, is there?

Phosphorus wrote:

Well, if we are into philosophy, your question corresponds to the maxim "You could not step twice into the same river." Debates since time of Heraclitus.

Ship of Theseus is more specific and actually more fun. Because besides a gradual full repair of an existing ship with full new set of planks -- so that ship contains no original elements; it also includes warehousing all the original material, inventing a technology to fix them, and assembling a second ship out of original elements.
Obviously, there's no set of spare parts of "you", to build a second set of "you" to run a comparison, is there?

I was thinking of ageing. I get angry far more easily now which I believe has to do either with neurological changes or with the body chemistry not working as good as before. And of course as years pass by one changes attitudes, believes ... Environmental factors also matter. I believe the difference a human experiences in 20 years is far more than if a ship gets all planks replaced.

Weatherwatcher1 wrote:

The newer engines don’t last as long between overhaul. Higher core temperatures and pressure help with efficiency but can increase wear. There have been CFM56 engines make it to 40,000 hours (10 or more years of service) although that is an anomaly. I doubt we will ever get another engine last as long on wing between overhaul as CFM56 since there is increasing demand on efficiency.

Source? I know RR has its particular issues with the Trent 1000, but as far as I can tell, the GEnx lasts just as long as the GE90 despite burning hotter, and the GE9X will last longer, though that is thanks to integration of CMCs in the hot section

patrickjp93 wrote:

Weatherwatcher1 wrote:

The newer engines don’t last as long between overhaul. Higher core temperatures and pressure help with efficiency but can increase wear. There have been CFM56 engines make it to 40,000 hours (10 or more years of service) although that is an anomaly. I doubt we will ever get another engine last as long on wing between overhaul as CFM56 since there is increasing demand on efficiency.

Source? I know RR has its particular issues with the Trent 1000, but as far as I can tell, the GEnx lasts just as long as the GE90 despite burning hotter, and the GE9X will last longer, though that is thanks to integration of CMCs in the hot section

The LEAP-1A is designed for longer life than the CFM-56.

Following the unprecedented times on wing recorded by current-generation CFM56 and V2500 engines, many expect their successors—the Leap and PW1000—to perform as well or better, with fewer but heavier shop visits predicted.
https://www.mro-network.com/engines-eng ... igital-age

I couldn't re-find the link, But I read a CFM-56 will see 5 shop visits during the life of an A320 (yes, first visit is a third of the aircraft life), while the LEAP is expected, after initial teething issues, to see one less.

Does anyone remember the compressor surge issue in the CFM-56-5 and -7? I didn't think so:

https://www.flightglobal.com/news/artic ... es-345359/

Older engines had time to solve issues. There is a reason for launch customer pricing. Also why BA/IAG and JetBlue now refuse to be launch customers. The CF-34-10/E-190 did not have a smooth EIS nor great maintenance:

https://www.bloomberg.com/news/articles ... st-problem


Lightsaber

PS,
I'm not discussing RR or Pratt issues as they have been discussed enough.

lightsaber wrote:

patrickjp93 wrote:

Weatherwatcher1 wrote:

The newer engines don’t last as long between overhaul. Higher core temperatures and pressure help with efficiency but can increase wear. There have been CFM56 engines make it to 40,000 hours (10 or more years of service) although that is an anomaly. I doubt we will ever get another engine last as long on wing between overhaul as CFM56 since there is increasing demand on efficiency.

Source? I know RR has its particular issues with the Trent 1000, but as far as I can tell, the GEnx lasts just as long as the GE90 despite burning hotter, and the GE9X will last longer, though that is thanks to integration of CMCs in the hot section

The LEAP-1A is designed for longer life than the CFM-56.

Following the unprecedented times on wing recorded by current-generation CFM56 and V2500 engines, many expect their successors—the Leap and PW1000—to perform as well or better, with fewer but heavier shop visits predicted.
https://www.mro-network.com/engines-eng ... igital-age

I couldn't re-find the link, But I read a CFM-56 will see 5 shop visits during the life of an A320 (yes, first visit is a third of the aircraft life), while the LEAP is expected, after initial teething issues, to see one less.

Does anyone remember the compressor surge issue in the CFM-56-5 and -7? I didn't think so:

https://www.flightglobal.com/news/artic ... es-345359/

Older engines had time to solve issues. There is a reason for launch customer pricing. Also why BA/IAG and JetBlue now refuse to be launch customers. The CF-34-10/E-190 did not have a smooth EIS nor great maintenance:

https://www.bloomberg.com/news/articles ... st-problem


Lightsaber

PS,
I'm not discussing RR or Pratt issues as they have been discussed enough.

Nah, dead horses must be beaten to death at least 6 times over.

strfyr51 wrote:

Engines can basically be overhauled as long as the Parts can be repaired or manufactured. I would invite any of you to try and book a tour of the United Airlines Turbine shop at San Francisco to see what the repair capabilities are in Jet engine repair and overhaul. I can assure you? You'd be amazed and impressed as I am whenever I go there. I used to come to work early just to walk through there as they had so much neat stuff going on there. In my 33 years working the Line at United that was the one place I regretted not ever having worked, Those guys are craftsmen at their finest, Though My specialty was working Live Airplanes and I have put my name on enough releases to estimate that could have a Billion revenue passenger miles flown on my signature alone with all the Maintenance releases I've put my name on without ever a mishap. I joked before that I was never afraid to take an airplane out of service as I was FAR more afraid of the FAA than I was of anybody at United.

Thank you for your career dedicated to safety. It is a tough choice to not 'release' when the plane is in a gray area condition wise, but the right thing to do. Aviation at all levels needs to be Safety First always. Your boss was probably also far more afraid of the FAA too, so if "strfyr" says its not going, I'm getting it fixed or find a replacement aircraft.

Air Canada had an aircraft where the engine had not been off the wing in 60,000+ hours, if I recall.