A B C D checks.
 

Would someone please explain to me how often a B737-400/800 "A"Check is performed and what in general terms is checked and/or replaced.

I've heard the term "D" Check too. I know that the higher the letter the more serious the check but I have no idea what it actually means and what the time interval between checks are.

As a pilot I think this is general knowledge that I should know.

Can someone please enlighten me! Thank you. :)

PS I've tried an internet search and a PPRuNe search and had no luck.

Try the following Link

http://en.wikipedia.org/wiki/Aircraf...tenance_checks

Should answer most of what you ask.

A Check / C check Intervals
 

For 737-800s, An A check is usually carried out every 450 (flight) hours - 530 hours. There can be up to 12 types of A checks (known as split checks). Depending on the operator, the checks are normally taken in to a hangar overnight where function checks and routine replenishments are carried out (Oils, greases, etc).
C checks are carried out every 18 - 20 months or so (Again limited by cycles / flight hours) These are split checks (depending on the operator) and can be split in to 6. Heavy work is carried out on the C checks and can last up to 6 days. This is the opportunity to carry out modifications / changes / upgrades etc.

All these checks are all part of the maintenance planning document that is issued with an aircraft by the manufacturer and approved by the NAA of manufacture. Changes can be made to intervals once each task is individually reviewed and a valid case for extending the interval is made. This is then reviewed by the NAA accordingly. If you want any further info, let me know!!!

D