Posts: 4291
Joined: Wed Oct 01, 2003 12:14 pm

Engine Overhaul Intervals

Wed Jun 30, 2010 3:17 pm

Can someone tell me what the overhaul intervals are for the following engines?

CFM56-3, -5, -7
CF34-3, -8

I have some data which suggests that overhaul for the CFM56 is every 10,000 hours, but that sounds quite low to me and I'm also not sure whether the same interval would apply for the -3 and the -7 which as I understand it are rather different engines. If the interval is every 10,000 hours I guess that means that an engine for a big carrier like Southwest which must do 3,000 hours a year would go for overhaul in every 3-4 years, which strikes me as being too frequent.

Any insight would be much appreciated?
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Engine Overhaul Intervals

Thu Jul 01, 2010 2:50 am

Quoting Airxliban (Thread starter):
Can someone tell me what the overhaul intervals are for the following engines?

The -7 is on an MSG3 maintenance program (I suspect the -5 is as well, but I'm not positive), so it doesn't have *an* overhaul interval, it's just got a ton of tasks with different intervals. They range everywhere from 50 hours to the lift limits on some of the parts. Major blocks of tasks come due at 1200/1600/2400/5000/6000/7500 hours.

The first thing that would require you to pull the engine, assuming you can pass all the intervening inspections, is the first buried part with a life limit.

Posts: 238
Joined: Tue Apr 25, 2006 8:10 am

RE: Engine Overhaul Intervals

Thu Jul 01, 2010 10:40 am

You're talking about an engine shop visit, right? This is where the engine is removed from the wing and sent to an overhaul shop. Its based on cycles, not necessarily hours. And, you are correct, I would say the CFMs on Southwest are going to be about every 3 - 4 years. The only CFMs I have worked on were from an atypical operator, and had longer intervals at the tradeoff of a much higher overhaul cost. PW4000's on longhaul aircraft go about 2,000 - 2,500 cycles between shop visits (baring an AD or parts failure). But, that could be many years.
Posts: 518
Joined: Sun Feb 04, 2001 10:34 am

RE: Engine Overhaul Intervals

Sat Jul 03, 2010 7:09 am

When I worked in the shop (many years ago) on the CFM56-3 the first cyclic lifed item was the HPT front shaft. On early models it was changed IIRC at 12,800 cycles although only one engine was actually removed when I worked on the shop floor due to the time expired part, most others ran out of EGT margin before making 12,800 cycles.

[Edited 2010-07-03 00:14:33]

[Edited 2010-07-03 00:14:55]

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