C Checks

[My names Turkish]

Can any one tell me where I could find the defenitions of what the various checks are? I hear people talk about aircraft needing a C Check or an A check, I understand that they are heavy maintenance but I was looking for the fine details. Cheers.

[Boss Raptor]

There are no simple 'definitions' as such...it is a very complex and multifacited subject which to oversimplify would not explain or answer or do it or you justice...it is a multitude of airframe and system (electrical, hydraulic, avionics, FCS) integrity inspections/checks/recalibrations, lubrication, cleaning etc. etc.

Get hold of the appropriate aircraft maintenance schedule which tells you the manufacturers recommended tasks and check periods in detail...however be aware that a C Check input will also include additional Corrosion Prevention and Control Programme (CPCP), Structural Inspection Programme (SIP) and Airworthiness Directives (AD) which can make up 2/3rds of the check...ask to see a 'Check Pack' for a C Check input which will show all such tasks would be a good example...speak to your local friendly heavy maintenance people

...and without getting too involved you should be aware that operators will define their own Maintenance Schedule tailored to their operating/utilisation requirement which although accomodating the basic manufacturers recommendation may well alter the phasing or periodicity of check inputs considerably - in some cases doing away with a C Check altogether...then we have MSG 2 and MSG 3 :E

[jettison valve]

Boss Raptor,

> in some cases doing away with a C Check altogether...then we have MSG 2 and MSG 3

I can´t see the link between setting up a Maintenance Schedule without a C check (or even without letter checks at all!) and MSG-3... (not familiar with MSG-2 though)...?!
Can you please elaborate on this.

Cheers,
J.V.

[Boss Raptor]

MSG-3 usually allows you to remove the C Check by re-allocating tasks...as does MSG-2 but not so easily...most MSG-3 users have elected to remove the C Check (but u dont have to, as user of MSG-3 schedule you have far more operator flexability as to Check and Task allocation in accordance with yr operational/utilisation needs and scenario...the old MSG-2 schedules were far less flexable but still could be C Check less if u wished and planned as such

To elaborate would go to pages...suggest you read the ATA MSG-3 concept document 'ATA MSG-3' as to more in depth detail on the core concept/principals differences between MSG-2 and MSG-3 methodology...it is available from the ATA website I believe

Or free here :)

http://www.nw.faa.gov/seattleaeg/AEGDOCS/msg32003.1.pdf

[xyz_pilot]

I my opinion how an airline chooses to work will in part depend on the facilities at its main base.

ie what can be done on site and what needs the aircraft flown to an other site.

[jettison valve]

Boss Raptor,

Well, I still don´t agree with you. MSG-3 is a method to analyze a technical system, a C-check -can- be the result of that (summing up several tasks that fit into the same FH/FC/Calendar Time regime).

The A380 is currently subjected to MSG-3, and as you may know, there won´t be any letter checks in the MRBR...! So, where is the link between MSG-3 and letter checks...?

Cheers,
J.V.

[Boss Raptor]

? and where did I say there was a link between letter or C Checks and MSG-3? in fact I have said the opposite...

'...and without getting too involved you should be aware that operators will define their own Maintenance Schedule tailored to their operating/utilisation requirement which although accomodating the basic manufacturers recommendation may well alter the phasing or periodicity of check inputs considerably - in some cases doing away with a C Check altogether'

i.e. Operators can define their own Check periods (and call it a Letter Check, IL, Big Check, Little Check call it what you like...) Just because it is no longer referred to by a letter it is still a check input all the same

and then added

'...then we have MSG 2 and MSG 3' indicating the 2 different types of maintenance schedule which also have to be considered - the old and the new

and also...

'MSG-3 usually allows you to remove the C Check by re-allocating tasks. so does MSG-2 but not so easily...most MSG-3 users have elected to remove the C Check'

i.e. no letter checks on MSG-3 for many operators...which is what you are saying - suggest you compare an MSG-2 schedule for an older aircraft type and the new MSG-3 schedule for that type - and u will see the massive difference in flexability which is why MSG-3 allows you to do away with letter checks even on older aircraft - by reallocating tasks accordingly

Clearly you are reading something in to this that I dont see:confused:

[dartman]

I think to answer the original question, in basic terms:

A check: daily inspection
B check: 50 hrs
C check: roughly every 12-14 months, requiring approximatly 3-6 weeks down time
D check: can't remember the interval here, 4-5 years rings a bell. Requires a reasonbly comprehensive rebuild.
Sorry for any errors, but I thought this got back to the original question. Mayby someone with more knowledge than me can flesh it out a little bit.

d.

[Boss Raptor]

D Check 15,000 to 20,000 Hours 5-8 years - all on MSG 2 type schedule - in basic terms

[My names Turkish]

Dartman : Yes that was more the answer I was looking for. Boss raptor explanations obvioulsy show that it was not as simple a question as I thought, and I bow to his superior knowledge.

I was just trying to get a rough idea of what was involved, but I understand there is no typical example. So say a 747. engines rebuilt, re wired, re weighed, re wired, tyres, re painted, re-rigged of sorts(I realize its not powered by cables mind!), interior refitted, instruments checked and serviced??? That sort of thing. Cheers.

[Boss Raptor]

Involved with relation to cost or manhours or what exactly?

If it's any help a B737-300 C Check is going to end up around $400K to $500K and a D Check anything $800K to a $mil at the bottom end - as a rough ballpark and not including any major nasties found, major mods., major component replacements or engine work

NB. not wishing to get complicated or create more room for misunderstanding ;) but the engines do not come under the airframe manufacturers maintenance schedule i.e. the C Check and are a seperate issue with a schedule of their own not necessarily running in sync. to the airframe check inputs

[My names Turkish]

Boss Raptor: This is why I asked. I am just doing my ATPL theory exams and I hear real pilots tossing that word around and hoping to be a real pilot one day myself, I dont want to get caught off gaurd when that day comes and not really know what is involved. There has been no mention of it in any of the subjects, which is hardly suprising as it could be considered usefull info:hmm:

I was just hoping you could give me an outline as much as possible as to what typically happens. I am getting some good info, keep it coming if you can think of anything else.

[Boss Raptor]

It's not mentioned in the ATPL's as it's not really a pilot thing...Engineering yes and then the finer points of maintenance planning/forecasting etc. is a subject in itself :ok:

Running out of relevant and/or concise things to say about the subject...unless as I suggested earlier you go to see more at yr friendly local maintenance planning/tech records department...

[WenWe]

Turkish, perhaps this will help - the basic maintenace schedule for an A320 is thus:

A check = every 400 flight hours. Usually performed on the ramp & will take 4 guys appx 4 hours. This is really just a fluids & gases service along with minor inspections & some function checks.

2A check = 800 hours, includes an A check at the same time. More functions, inspections, filter changes & a couple of boroscope inspections on the engines. This is done in the hangar & will take a day to complete for appx 20 guys. Time limited parts (batteries, slides etc) will normaly be changed at this time.

4A check = 1600 hours, includes 2A & A checks. As above but again a bit more involved.

Most operators combine elements of these 2 checks so that the same check is carried out every 800 hours.

1C check - every 18 months, includes 4A,2A & A checks. Much deeper level of inspections, which will require removal of exterior fairings, interior fixtures, galleys & lavs etc to accomplish. Will take 4 days to a week.

2C check - every 36 months, includes 1C.4A,2A etc etc

3C - can't remember if there is one

4C - big check! Couple of weeks in the shed. Corrosion prevention program will be carried out at the same time.

That lot's from memory , so sorry if details are a bit out but you'll get the idea.

Engines, as mentioned, are not replaced or repaired on the same schedule although these checks will have engine servicing items (meaning fluid & filter changes) & inspections as part of them.
Most of the engine will be an "on condition" item, where it is only replaced (or the engine removed & sent for overhaul) when inspection shows up a defect.
There are some parts however that have a finite life limit, in hours or cycles, at which time they must be replaced. This usually means sending the engine away for overhaul - compressor discs being an example.

Landing gear are much the same. IIRC they are changed after 6 year in the A320's case.

HTH

[Boss Raptor]

Very good/nice example WenWe - tks :ok:

[My names Turkish]

WenWe, Thank you for that, that was the sort of things I was looking for, it now makes more sense!:ok: