Whenever work is accomplished on an aircraft, the maintenance must be documented in accordance with the requirements found in the Federal Aviation Regulations (FARs) Parts 43.5, 43.9, 43.11, and 91.417.
The work includes any and all maintenance or modifications accomplished on the aircraft or component part of the airframe, engines, propellers, and appliances of the aircraft.
FAR Part 43.5 states that no authorized person can return an aircraft to service without a maintenance entry being accomplished.
FAR 43.9 (a) states that each person who maintains, performs preventative maintenance, rebuilds, or alters an aircraft, airframe, engine, propeller, or appliance shall make an entry in the maintenance record.
FAR 43.11 states that detailed entries are required to be made by maintenance personnel in the aircraft records after performing an inspection, including the content required for the maintenance entry.
For aircraft operated under FAR Part 91, General Operating and Flight Rules:
FAR Part 91.405 states that each owner or operator of an aircraft shall ensure that maintenance personnel make appropriate entries in the aircraft maintenance records indicating the aircraft has been approved for return to service.
For aircraft operated under FAR Part 135, Operating Requirements: Commuter and On-Demand operations and Rules:
FAR 135.439 states that each certificate holder must keep records using the system specified in its FAA approved manual of the maintenance, preventative maintenance, and alterations it performs.
Maintenance personnel are required to make a proper maintenance entry every time work is accomplished on the aircraft. There are no exceptions to this rule.