morhas
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Aeroengine Maintenance Schedule

Sun Jun 25, 2006 8:53 pm

Hi,

Can anybody tell me or show me some information about maintenance schedule of aeroengine from new? Between GE and RR, which is better in term of maintenance cost?

Morhas
 
EMBQA
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RE: Aeroengine Maintenance Schedule

Sun Jun 25, 2006 9:12 pm

Every aircraft engine I've ever worked on was 'on condition'. That means there is no schedules maintenance unless it breaks.. You add oil when it needs it and that is about it. Of course there are routine inspections when you open the cowling and do an external inspection, maybe pull a scavenge screen and inspect it... but that is about it. Then every several thousand hours it gets pulled for overhaul.

[Edited 2006-06-25 14:23:38]
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fr8mech
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RE: Aeroengine Maintenance Schedule

Mon Jun 26, 2006 4:18 am

Quoting EMBQA (Reply 1):
Then every several thousand hours it gets pulled for overhaul.

Engines for major carriers are no longer 'hard time'. They are replaced on condition. If an operator has an FAA approved trend monitoring program, the engine remains on wing until a problem is detected that requires it be pulled.

Engines receive periodic internal inspections (borescopes) and external inspections.

Oil is added when needed and this is monitored via log book and computers. Any increase in oil consumption is investigated.

Routine maintenance is performed periodically. Oil filter, fuel filter, ignitor replacements. Accessories are also serviced and inspected.
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n8076u
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RE: Aeroengine Maintenance Schedule

Mon Jun 26, 2006 4:57 am

Fluid levels are checked quite often (engine oil every flight). The chip detectors are checked, filters replaced, routine preventative maintenance (fan blade lube, for instance on some engines) occurs and visual inspections are carried out on a regular basis (say, every 500 hours at an "A" check or something along those lines). We also drained the oil tanks and refilled with fresh oil during "C" checks at UA.

Chris
Don't blame me, I don't work here...
 
AussieAMEgirl
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RE: Aeroengine Maintenance Schedule

Tue Jun 27, 2006 3:54 pm

Quoting Fr8Mech (Reply 2):
Engines for major carriers are no longer 'hard time'. They are replaced on condition. If an operator has an FAA approved trend monitoring program, the engine remains on wing until a problem is detected that requires it be pulled.

sheesh....er can anyone confirm if that is the same over here (Aus), I havent worked on airlines for 5 years now, and last time I did everything was lifed.

In the military (where I am now) everything in an engine is lifed, excepting perhaps things like screens and filters which are OC. Thats on a GE T700.
 
n8076u
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RE: Aeroengine Maintenance Schedule

Tue Jun 27, 2006 5:00 pm

I've been involved with many engine changes during my aviation career, most of them on 747's, with a sprinkling of 727, 737, 757, 767 and 777 engine changes here and there. Not once have any of those engines been pulled because it or a component in it had timed out. There was always a physical problem of some sort necessitating the engine change, from shavings in the chip detectors, bad bearing seals, severe bird strikes, in flight shutdown or surging, failed borescope inspection, or a failed stall margin or power assurance run-up test.

Now, I will say that most of my experience regarding the engine changes was in line maintenance, as they may very well pull a high-time engine for replacement during a heavy check, but a lot of the time during HMV, the originally removed engines get an off-wing check while they're sitting at the back of the hangar waiting to be put right back on.

Chris
Don't blame me, I don't work here...
 
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NZ1
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RE: Aeroengine Maintenance Schedule

Tue Jun 27, 2006 5:09 pm

I think QF and DJ operate the same in Australia too. Here at NZ, everything is on condition except for your filters/ignitors etc at every A or C Check. All temps/oils etc are monitored by ACARS and recorded inito our mx program. Long term trends are an aid to planning for when an engine is likely to have to be removed.

NZ1
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kaddyuk
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RE: Aeroengine Maintenance Schedule

Wed Jun 28, 2006 3:30 am

Quoting Morhas (Thread starter):
which is better in term of maintenance cost?

I couldn't tell you which was "better" but i've heard figures of around $2 Million for a major overhaul. Not sure if that was true...
Whoever said "laughter is the best medicine" never had Gonorrhea
 
Tristarsteve
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RE: Aeroengine Maintenance Schedule

Wed Jun 28, 2006 3:39 am

A lot of engine parts like rotor discs and fan blade hubs are lifed. But the lives are very high and the engine is usually removed for some other reason first. When the engine is removed the engine shop sit down and work out what to change to give the engine a good life, but not to throw away too much life by taking things off early.
I have removed engines time expired, but that was a few years ago. The lives of these components have grown with better materials and it is a rare event nowadays.
Back in 1978 with the forged HP Turbine blades on the RB211 we had a hard life for the HP Turbine of 1200 cycles. This was because they were regularly failing soon after that. Then came single crystal blades and the life doubled, and now the skies the limit. I believe the record for on wing time is now around 35000 hours for CFM56 and RB211-535.
 
MarkC
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RE: Aeroengine Maintenance Schedule

Wed Jun 28, 2006 7:07 am

2 million would be a fairly major overhaul on a 94" PW4000. The 90K version of the 112" is another story. The LPT alone could go over 2 mils. There is an incredible blade count in the LPT. 7 stages.

All PW rotating parts are life limited. The vast majority are 20,000 cycles. Some particular parts on high thrust models can be lower. But 20,000 cycles is a lot. Most of the long haul engines will never get there. If you average 5 hours per cycle, that's 100,000 hours. How long does that take...30 years? The first PW engine to go 100,000 was last year. If you are JAL domestic, 20,000 cycles is about 25,000 hours.
 
greasespot
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RE: Aeroengine Maintenance Schedule

Wed Jun 28, 2006 8:58 am

Most of our engines from the PW120's to the JT8's have cycled or houred out.

The PW120 is on condition however the HP disk and Cover plates all have a 15000 cycle life. This usually coincides with an HSI. The rest of the rotating parts have a 30 000 cycle life.

All we do is oil filters( both scavenge and main) every 500 hours, and nozzles and flow divider at 1500 hours and a full engine boroscope at 1500 hours.

It can be hard timed for some operators then it has an 8000 hour life.

On the JT8 the life of the rotationg parts in most cases are 30k hours and 20k cycles, except for the c1 which is 20k cycles and no hour life. Some of the other disk lives are lower depending on the the part number of the disk.

Plus the Jt8 has a 4year or 8 year calendar life from AD 2003-12-07 on the HPC( stages 7-12) for a corrosion inspection. It gets a 4 year depending on the C-9 part number.

Our RR darts are on a 7000 hour TBO. They require more work and usually a repair at the half way mark.

Other than that as long as it does not cycle or hour out it keeps going unlit it comes appart in flight... [hyper]

GS
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n8076u
Posts: 419
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RE: Aeroengine Maintenance Schedule

Thu Jun 29, 2006 4:20 am

Very informative posts, TristarSteve, MarkC, Greasespot.

I figured there would be hard limits on some of the parts, but that a lot of the time, something would go wrong necessitating the engine change before any of those time limits are reached. Whatever the turbine shop did after that I wasn't privy to, so thanks for some insight into that.

Our turbine shop had posters with photos of certain engine parts, and their cost was labelled next to the photos. It is insane what some of those parts run!

Chris
Don't blame me, I don't work here...
 
kgfive
Posts: 59
Joined: Wed Oct 26, 2005 7:32 am

RE: Aeroengine Maintenance Schedule

Thu Jun 29, 2006 5:17 am

Quoting N8076U (Reply 11):
Our turbine shop had posters with photos of certain engine parts, and their cost was labelled next to the photos. It is insane what some of those parts run!

I have been doing a repair today on an CF6 - 80C2 HPT STG1 DISK/SHAFT which is to remove wear from up inside the web area of the shaft....normally called " armpit repair " as the area getting repaired resembles your ARMPIT added to that you cannot see where the tooling is going so you need to trust your calculations and the accuracy of the CNC Machine.....AND.....on the repair paperwork is a little box giving you the information which you deffinatly do NOT need...the price of the component which in this case is $300,000....just what you want to know as you hit the GREEN ( start the machine ) button  worried  even better feeling at 4am on night shift

 eyepopping 

Yes lots of engine components are very expensive..........and great feeling you get when you have a little accident  weeping 

KG
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