If recips were made nowadays

[Shortround6]

A lot of life of engines depends on their use, The "at least 3,000 hours" was pulled from memory of old magazine articles. I just checked the internet and found this for the smaller PT-6 engines used in the Beechcraft 1900.

"Overhaul:
TBO is 9,000 hours or 14 years, whichever comes first (since new or
since overhaul as applicable)"

This is with a specific inspection and use schedule. (min 30 hours a month) and is a modification of the previous overhaul life. and this is from a 2005 article.

Or see; Turbine DC-3 Turbo Dakota DC3 Turbine Conversion Aircraft from Dodson International Parts

6000 hours basic TBO for essentially the same engine.

A modern piston engine may be able to do better than an old one with modern materials/manufacturing but modern turbo-props and turbo fans can exceed 10,000 hours depending on model, application and maintenance program. And maintenance between major overhauls is a lot less, ( no changing 24-56 spark plugs or adjusting 28-56 valves ever few dozen to few hundred hours)

There is a reason why even crop dusters replaced P&W R-995 and R-1340 engines decades ago. The Turbines were much more expensive to buy up front but the lower maintenance costs per flying hour tipped the balance.

 

[swampyankee]

Another issue killing off spark ignition piston engines if fuel: avgas availability is very poor in many parts of the world, and getting worse. Jet-A is much easier to move around and store than avgas, and turbines can, at least in principle, use road diesel.

 

[FLYBOYJ]

I just checked the internet and found this for the smaller PT-6 engines used in the Beechcraft 1900.

"Overhaul:
TBO is 9,000 hours or 14 years, whichever comes first (since new or
since overhaul as applicable").

Not as simple as that! That TBO will depend on if you're doing engine trending, and hot section inspections. It varies for each -# of PT6 engine and the aircraft they're installed on.

 

[gumbyk]

Not as simple as that! That TBO will depend on if you're doing engine trending, and hot section inspections. It varies for each -# of PT6 engine and the aircraft they're installed on.

And that's the PT-6.
The LTS-101 doesn't even have a TBO. Its all on-condition.

 

[Shortround6]

Not as simple as that! That TBO will depend on if you're doing engine trending, and hot section inspections. It varies for each -# of PT6 engine and the aircraft they're installed on.

Well, I did say which aircraft and "This is with a specific inspection and use schedule. (min 30 hours a month) and is a modification of the previous overhaul life."

It is not simple and getting a bit more complicated all the time but with the engine trending, inspections, oil analysis and use cycles figured in it appears that the turbines can hit overhaul lives that reciprocating engines can only dream of.

Abuse can shorten life drastically just like a piston engine, and "abuse" can mean not using the engine on a regular basis.

 

[razor1uk]

Many oils; usually after becoming 'gummy'/congealed, can become acidic if left too long and they 'settle' like wine in a barrel - various additives and impurities within the 'still oil' over time separate due to natural breakdowns due to specific gravities and molecular preferences for elemental interlocking/breakdowns.
Any reasonably complex mechanical machine or engine can corrode or suffer from more from a lack of usage, if it isn't used appropriately at often regular intervals - I'm sure most vehicle museums drain their cars, bikes, trucks and lorries etc of most of their engine oils - if they really know what they are doing; though to cover guest questions they will say '..it is to stop leaks.' which is only at best 'tertiary' answer..

 

[Trilisser]

One thing to remember is that the long lives of many modern turbines is partially due to the pampering they get. I really wonder what would the TBO be for a modern turbofan if operated in really rough WW2 field conditions (unpaved dusty fields, alternating with slush and mud, maintenance carried out in the open etc.)...

 

[FLYBOYJ]

One thing to remember is that the long lives of many modern turbines is partially due to the pampering they get. I really wonder what would the TBO be for a modern turbofan if operated in really rough WW2 field conditions (unpaved dusty fields, alternating with slush and mud, maintenance carried out in the open etc.)...

A better comparison would be a turbo prop like a PT6, the TBO time would be about the same under the same conditions.

When you say "pampering" what do you mean? If an engine is operated within POH parameters if should make TBO. There's really no pampering you could do to a turbine, with the exception of using an APU to avoid hot starts and avoiding FOD rich environments.

 

[razor1uk]

The pampering is insinuated by the remaining part of Trisslers sentence, but turbines are thought to have easier and more precautions taken with them, certainly nowadays than most IC engines. Avaiation IC engines have more pampering than they did back then too, and that's normally known as progress.

 

[FLYBOYJ]

The pampering is insinuated by the remaining part of Trisslers sentence, but turbines are thought to have easier and more precautions taken with them, certainly nowadays than most IC engines. Avaiation IC engines have more pampering than they did back then too, and that's normally known as progress.

It depends on what engine, what aircraft it's installed on and how it's being operated, but for the most part "not really." I've worked on and flown both recips and turbines; you operate them to the POH. The only "pampering" you're going to ensure is that on recips you're not operating at high CHTs, you're not over/under boosting (if turbocharged) or running the engine above red line RPM, and finally you're making sure your engine is properly maintained. On a turbine, you're watching EGT on start and you're not doing anything to stack up temps, invite FOD or operate in an environment where you can induce compressor stall.

 

[swampyankee]

With turbines, a lot of effort goes into making a lot of the "pampering" automatic; a lot of the testing I was involved in when I was a development engineer at Lycoming was just for that purpose: let the pilot slam around the power lever any which way, and the engine wouldn't surge.

 

[Shortround6]

One has to wonder how much pampering crop duster engines get and how much different their operating conditions are compared to WW II aircraft. Crop dusters were pretty early users of turbine engines.

Helicopters use turbine engines and anybody who has been near one on even paved parking lot "emergency" landing site ( med-evac) knows how must dust-dirt they can stir up. Granted Helo engines may have shorter life than a fixed wing turbine but some of that is the higher average power levels used ( reciprocating helo engines usually have a shorter TBO than the equivalent fixed wing engine.)

 

[FLYBOYJ]

With turbines, a lot of effort goes into making a lot of the "pampering" automatic; a lot of the testing I was involved in when I was a development engineer at Lycoming was just for that purpose: let the pilot slam around the power lever any which way, and the engine wouldn't surge.

Bottom line, if you're operating an aircraft engine, any engine within the POH, there is no such thing as "pampering."

 

[FLYBOYJ]

One has to wonder how much pampering crop duster engines get and how much different their operating conditions are compared to WW II aircraft. Crop dusters were pretty early users of turbine engines.

And many of them are operator owned so they have to be careful with their investment. OTOH some of the most poorly maintained aircraft I ever seen were dusters.

Helicopters use turbine engines and anybody who has been near one on even paved parking lot "emergency" landing site ( med-evac) knows how must dust-dirt they can stir up. Granted Helo engines may have shorter life than a fixed wing turbine but some of that is the higher average power levels used ( reciprocating helo engines usually have a shorter TBO than the equivalent fixed wing engine.)

I worked on an A Star that was used for medical transportation. We did a lot of dirt and parking lot LZs and never had issues, a lot of it is the way the engine is configured on the airframe with the intake placed in a low FOD risk area.

 

[razor1uk]

...On the roof, so stones and larger fod is less likely, and being largely air moving, small particular dust wont do so much to more modern turbines that don't use too much oil and have better oil consumption and leakage rates, or have as low a flow compression ratio's as the WW2 era turbines either.

 

[Trilisser]

By pampering I mean that e.g. when sand was used to combat slipping due to ice, this sand had to be cleared away when turbine engined Fouga Crapsters (aka Magisters) operated on these runways as their turbine engines had to be pampered. When erecting temporary shelters for FAF Hornets, special care has to be taken by using self-locking nuts on any shelter structures as, again, Hornets' turbine engines have to be pampered. When I served at an FAF airbase operating turbine engined aircraft, walking across the runways was forbidden as "sand or small stones may be transferred to runways". This is what I mean by pampering.

 

[razor1uk]

Ah, that's a little more than perhaps the USAF does all the time - allegedly.
Although it is what the Marines and USN do; well hyváá mies vai nainen (good men or women) want to minimise your national expenditure and lessen the need to order more spare parts at inflated prices from over the pond - sort of like that which lead to the tragic story of the FAF's frankenplane F/A-18.

 

[swampyankee]

Well, Boeing did have to make some revisions to early (JT8-D engined) 737s as they could be very good vacuum cleaners on gravel runways, a problem the BAe146 (puts in plug for airplane I was involved with -- I was a test engineer at Lycoming) completely avoided.

Turbine engines tend to be pretty robust -- when I worked at Lycoming, the guys working on the AGT-1500 (Abrams engine; unjustly maligned by diesel bigots) did have a few problems with sand eroding the compressor blades. This remained a problem until Chrysler found out how to build air filters -- but, nonetheless, it had a TBOH and MTBF that were much greater than the diesels it competed with (iirc, the TBOH for the AVDS-1790 in the M60 was something under 100 hours; the AGT-1500 was already getting to the point where its TBOH was approaching the tank's design life)

 

[FLYBOYJ]

By pampering I mean that e.g. when sand was used to combat slipping due to ice, this sand had to be cleared away when turbine engined Fouga Crapsters (aka Magisters) operated on these runways as their turbine engines had to be pampered. When erecting temporary shelters for FAF Hornets, special care has to be taken by using self-locking nuts on any shelter structures as, again, Hornets' turbine engines have to be pampered. When I served at an FAF airbase operating turbine engined aircraft, walking across the runways was forbidden as "sand or small stones may be transferred to runways". This is what I mean by pampering.

That's not pampering, that's operating smartly by implementing FOD controls. I work at USAFA and we do the some practices on all the GA aircraft and gliders operated here.

 

[FLYBOYJ]

Ah, that's a little more than perhaps the USAF does all the time - allegedly.
Although it is what the Marines and USN do; well hyváá mies vai nainen (good men or women) want to minimise your national expenditure and lessen the need to order more spare parts at inflated prices from over the pond - sort of like that which lead to the tragic story of the FAF's frankenplane F/A-18.

Not true - depending on the base the USAF FOD programs are huge, this I know as a fact, I'm the airfield FOD monitor at USAFA (among other things!)