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Maintenance Checks Deciphered?  
User currently offlineDeltaGator From United States of America, joined Sep 2005, 6341 posts, RR: 12
Posted (10 years 5 months 3 weeks 2 days 7 hours ago) and read 2992 times:

Would someone give me a quick overview of the differences between C & D checks and what exactly is entailed in each of them. I found this link with a couple of answers but it didn't go into too much depth.


I'm interested in how C checks get split up and what all gets done during a D check. How long are the planes out of service during the checks. General guidelines of when they are done (hours, rotations, or something else as the deciding factor.) Things like that are what I am after. And oh, I know a lot of planes get new paint during heavy checks but how long does it generally take to paint a plane (vague timeframes since I know planes vary in size.)

Thanks for the help. I'm not incredibly well versed in the TechOps side of the house and I'm just a wee bit curious to add more trivial knowledge to my brain.

"If you can't delight in the misery of others then you don't deserve to be a college football fan."
7 replies: All unread, jump to last
User currently offlineAmtrosie From United States of America, joined Jan 2005, 274 posts, RR: 0
Reply 1, posted (10 years 5 months 3 weeks 2 days 5 hours ago) and read 2974 times:

You have asked a mouth full!

C checks (and D's) vary for each aircraft owner. It basically comes down to an agreement between the owner/operator and the regulating body (the FAA in the US). They all will follow basic guide lines put forth by the manufacturer. Aircraft utilization plays a big role in determining what gets done when.

Now, your question: A "C" check is a basic removing of most inspection panels and doing a in-depth visual inspection followed by rectifying all discrepant items. There will be numerous operational checks included in this work scope. A "D" check will be a THOROUGH inspection of the aircraft with many (or most) of the major components being removed for more comprehensive inspection/scrutiny.

Because of this time consuming (non revenue generating) inspection the various parties have corroborated on a plan to perform portions of the "D" check while working through the "C" check. Your maintenance personnel are already in the area so, why not "kill two birds with one stone", is the thinking. The aim is to keep the aircraft down for no more than 4-6 weeks.

The paint is addressed on a "as needed basis". Touch up of paint is an on-going endeavor, and a complete re-paint is done every 5-7 years, depending. Understand that paint is a corrosion prevention measure, making it look nice is secondary. Most paint jobs can be done in a week.

I am sure there are more questions but to be specific is absolutely impossible.

User currently offlineTristarSteve From Sweden, joined Nov 2005, 4353 posts, RR: 33
Reply 2, posted (10 years 5 months 3 weeks 2 days 4 hours ago) and read 2964 times:

Or you can split C checks into small packets and then do bigger D checks.
We split our C checks into packages that can be berformed in two nights and a day. Three packets equals a C check. These packets come about every 1500 hours or 6 months. D check is done evry 6-10 years. But the aircraft will need to go in the hangar evry now and then for jobs which take more than 36hours. These jobs are collected together and done when required.
Painting is carried out in a separate hangar all by itself because of the fumes.A paint input takes about a week

User currently offlineHAWK21M From India, joined Jan 2001, 31875 posts, RR: 54
Reply 3, posted (10 years 5 months 3 weeks 1 day 10 hours ago) and read 2885 times:

Quoting TristarSteve (Reply 2):
A paint input takes about a week

Which type.
A B747.

Think of the brighter side!
User currently offlineWhiskeyflyer From Ireland, joined May 2002, 224 posts, RR: 0
Reply 4, posted (10 years 5 months 3 weeks 1 day 9 hours ago) and read 2875 times:

C & D checks are terms that are often mis used.
Most modern aircraft on phased programmes (i.e. sections of the C check are carried out during a B check and phased over say four years. All to do with MSG guidelines). And on the older aircraft you seldom just do a C or D check, there are also all those other tasks to do such as corrosion prevention (which involve taking you cabin apart) any mods required, overhaul (to say the gear), cabin changes, part changes, upgrades, new entertainment systems, etc. etc etc
What is put together is called the workpack and it varies per aircraft and per operator, so how long a C or D check, more like how big your workpack (but if you want it our a certain date, pay more and ask Luftansa Technik, you want to save cash and end date a little flexible, ask a facility in South Asia)

User currently offlineSaintsman From United Kingdom, joined Mar 2002, 2065 posts, RR: 2
Reply 5, posted (10 years 5 months 3 weeks 15 hours ago) and read 2837 times:

Maintenance check durations also depend on whether they are working 24 /7.

The term C/D check is also vague as there is usually additional maintenance associated with it. A particular item of the check maybe to check for corrosion. If there isn't any then its on to the next check. If there is corrosion then you have to rectify it. That is not part of the C Check and is extra. It is normal to include associated rectification as part of the price of the check but usually upto a limit (say 50 manhours per item). If the rectification will take more than 50 hours it is charged seperately. All this additional work is carried out in the scheduled down time of the aircraft.

Also, there are more checks that might happen at the same time. Some checks are carried out on a calander basis, some on a flying hours basis and some on a cyclic basis (there are other examples). If these requirements coincide with the C Check then they will also be carried out.

And finally there are deferred maintenance requirements. Sometimes you get faults that do not have to be fixed straight away (maybe a broken bit of trim or you don't have the necessary spares at the time). These sort of faults are fixed when it is convenient and C /D checks is the best time to carry them out.

As for paint, we would allow 10 working days for a full strip and repaint on a wide bodied aircraft.

User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 23
Reply 6, posted (10 years 5 months 3 weeks 11 hours ago) and read 2821 times:

They use this time to "load" the checks with items such as modifications or re-configurations.

There are "Maintenance Planners" who have the wonderful task of planning out the maintenance and making sure that the aircraft is down for a short a time as possible. As has been said above, aircraft only make money when they are carrying passengers... At any other time they are just expensive lumps of metal (or in the case of airbus... plastic)  Wink

Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineDeltaGator From United States of America, joined Sep 2005, 6341 posts, RR: 12
Reply 7, posted (10 years 5 months 3 weeks 3 hours ago) and read 2798 times:

Thanks for the info guys. It helps me out knowledge-wise.

Quoting Kaddyuk (Reply 6):
There are "Maintenance Planners" who have the wonderful task of planning out the maintenance and making sure that the aircraft is down for a short a time as possible.

The Logistics folks at an airline amaze me. The sheer capability of moving tons of planes around generally ontime boggles the mind.

"If you can't delight in the misery of others then you don't deserve to be a college football fan."
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