Cost for jet rebuild

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I found a site that mentioned up to 500k to rebuild one engine on a small private jet plane and posted TBO was 4000 hours, the first rebuild would probably be in the 250k area, because the big life cycle parts may have more time. So what would the price be for a 737 or 787 or airbus? I'm thinking 2.5 to 3 Million per engine.
 
Rolls Royce/Pratt Whitney/GE are the big players in large jet engines.
 
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Originally Posted by Exhaustgases
I found a site that mentioned up to 500k to rebuild one engine on a small private jet plane and posted TBO was 4000 hours, the first rebuild would probably be in the 250k area, because the big life cycle parts may have more time. So what would the price be for a 737 or 787 or airbus? I'm thinking 2.5 to 3 Million per engine.


Depends on the workscope, and the reason for the 'rebuild'. Even the same engine operated in different conditions can have different costs. And if there are any ADs, those have to be incorporated as well.

The big trend over the past decade or two has been merely to sign a contract for 'power by the hour', in which the engine is leased from the OEM, and they do remote online monitoring, and when indicated, the engine is removed and completely overhauled at their expense for whatever workscope is required for EGT margin restoration, ADs, LLPs, upgrade kits, etc. Hence, the actual cost is invisible to the customer, and the OEM ends up in a real financial pickle if they sell a junk engine.
 
A jet engine overhaul is far more involved than you are likely aware of. My company charges around 5 - 10 million for a CF6-80c2 overhaul.

Jet engines are broken down into modules: fan/fan frame, stage 1 LPT blade set, LPC booster/stator, HPC rotor/stator, CRF, combustor, LPT rotor/stator, TRF plus the shafts that tie the low pressure ends together which run straight down the center of the engine (mid shaft/fwd shaft - part of the LPC module). There are three gearboxes - inlet/transfer/accessory - and six main-line bearing sets. *LPT = low pressure turbine, LPC = low pressure compressor, HPC = high pressure compressor, HPT = high pressure turbine, CRF = compressor rear frame, TRF = turbine rear frame.

For an engine to be classified as "Overhauled" or heavy maintenance/full overhaul workscope, only the main modules need be completely disassembled, measured, repaired, and reassembled. Engine life is set by "cycles" and not hours so when a module is built each life-limited part (LLP) in the module must meet a minimum number of remaining cycles. Generally 3000 cycles is used as the basis. Some customers may only want their engine rebuilt with 2,000 cycles remaining because they don't want to replace an LLP. The lowest remaining time LLP will determine the engine cycles remaining.

While the overhaul costs are mind boggling, here is some trivia that makes me scratch my head every time I see the invoices: HPT stage 1 turbine blade set, qty 80 blades, cost: 1.04 million ($13,000 each). HPT rotating interstage seal, qty 1, cost: $1 million. HPT fwd outer seal, qty 1, cost: $1 million. The two HPT turbine disks have a combined cost of about 600,000. The thermal shield is $200,000. These prices relate only to the high pressure turbine module. There's still the fan, LPC, HPC and LPT to be addressed.

Rarely is an overhaul performed using all brand new parts so those new parts prices are not incorporated in every overhaul. However, when an engine is inducted for LLP expiration then all of the out-of-time disks, shafts, and seal will get replaced with parts that have remaining life cycles requested by the customer. I do recall rebuilding a few engines for an Arab king who specified that all brand new parts be used. He literally had money to burn.

This is a very vague description of some of what is involved with jet engine maintenance. It's very complex and expensive. I'm surprised that we can still buy airplane seats so cheaply with all of the associated expense tied to the flight.
 
I've read where a fair amount of maintenance is outsourced overseas for cost savings and overseen by A+P IA folks from here for sign offs. Language/communication problems may occur as well. It doesn't sound like a good situation to me.
 
25 years ago I toured the Kalitta airline facility. They dealt with large airplanes (747s, DC-10s). At the time they said it cost $ 2M to rebuild an engine.
 
Originally Posted by Lapham3
I've read where a fair amount of maintenance is outsourced overseas for cost savings and overseen by A+P IA folks from here for sign offs. Language/communication problems may occur as well. It doesn't sound like a good situation to me.

The situation is just fine. Airlines have sent aircraft to South America for years for maintenance with no increased risk. Those stations are certified by the FAA and must get recertified every 1 to 2 years, depending on the station. I work with these stations often and have never had an issue with communication- most every management level employee speaks English on top of my company having mechanics and engineers working down there that can run interference for me if need be. If there was any added risk to make use of these foreign repair stations, then neither the FAA or the airline would use them. However, there's no proven added risk and it does provide a source of cheaper (see: Non-Union) labor as well as keeping hangar space available state-side.
 
The carrier I was on in the Navy is about 60% of the way thru it's midlife refueling. It steamed somewhere around 3 million nautical miles in 25 years, and the total refueling charge including other upgrades and refitments was $2.8 billion. Considering that there were significant structural upgrades and replacements, I'd estimate the refueling was maybe 40% (that's a WAG obviously, as I haven't ever really priced reactor-grade nuclear material on the street recently
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), meaning it works out to somewhere around $325 per mile for the carrier during that timeframe. Not a bad price for 100,000 tons of mobile diplomacy, 6000+ sailors and airmen, and her 80+ aircraft!
 
So very roughly $10 million times 2 engines divided by 3000 flights means it costs the airline $6666 per flight toward engine rebuilding. With 200 passengers that would end up $33 per passenger per flight.
 
With modern high bypass engines I wonder if that leads to longer intervals between major maintenance of the engines.
 
Originally Posted by sloinker
With modern high bypass engines I wonder if that leads to longer intervals between major maintenance of the engines.


Yes, there are engines like the CFM56 that go 25k+ hours "on wing". Especially with moderate sectors, and derated takeoffs.
 
Our Gulfstream G550 with Rolls Royce BR710 engines recently had both engines "midlife'd" (much like a hot section) . We were maintaining and operating the engines "on condition" (requires frequent borescopes and more intensive maintenance) however before reaching 4000 hours (the midlife/hot section requirement when an operator chooses hard-time maintenance) we experienced LH engine compressor stalls on startup.

The LH engine cost $2.7M to inspect and repair. The RH engine was a bit less at $2.5M.

While the compressor section would not typically be disassembled during a hot section inspection, our compressor clearly had some 8th stage coating loss, (supposedly) leading to the compressor stalls. (what actually caused the startup stalls is open for debate, as the variable stator vanes were sticking due to poor quality plastic bushings)

The coating is a Metco flame sprayed coating that provides a very tight blade tip clearance by wearing away at first startup. Ours was 100% missing on the compressor drum (typical) and 50% missing on the 6th through 8th stage compressor housing. The result was excessive blade tip clearance and a massive repair. They now use tougher Zirconium coatings.

[Linked Image from upload.wikimedia.org]



The fan is considered stage 1 of the compressor, so you can see that stage 8 is quite a bit smaller, with blades that are about 2 inches in length.
 
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Well, I don't know what happened to your last post (apologize) as I attempted to quote it but my question was:

Understand but what is that centrifugal-looking element at the front of the core assembly. Is that a diffuser?
 
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