Definition
Required by rule, regulation, or order; not optional. In aviation maintenance, a mandatory item must be performed or complied with — there is no discretion to skip it.
Plain English
You have to do it. It is not a choice or a suggestion.
Context Anchor
Seen in maintenance instructions, inspections, service information, and regulations where a required action is being identified.
Derivation
From Latin mandatum, meaning 'a command' or 'order.' The word still carries that original sense — something ordered, not something recommended.
Why Pilots Care
Non-compliance can ground the aircraft or create legal liability.
Intuition Check
Do not read mandatory as meaning important but optional. In aviation, mandatory means required and must be complied with.
Example Sentence 1
Compliance with the Airworthiness Directive was mandatory before the next flight.
Example Sentence 2
Replacement of the part became mandatory after the service bulletin was issued.