To explain the theory of pilots knowledge of aircraft systems..
Many pilots think that because he/she presses button A, Indicator D will Light up and the pertinent actions will have taken place.
Many pilots will not know the sequence of events that actually take place as they have learnt them from the operators manuals not the manufacturers maintenance manuals.
The Difference?...
Maintenance System descriptions will cover all aspects of that system in toto. Operator Manuals cover the effects of actions taken - not normally the sequence of operations before that effect.
e.g.
Pilot actions are taught as:
Button A is pressed, opens valve C to open allowing pressure to be felt at Valve E opening Fuel in Tank 3 to feed the APU and bypass fuel from Tank 4
Engineers are taught that:
Button A is pressed, causing power from Bus G Relay B to switch over, allowing Bus H power to switch Relay I opening valve C - ect, ect.
[/INDENT]As I said - Many pilots are that way - not all.