Which document is essential for documenting the maintenance history of an aircraft?

The maintenance logbook is essential for documenting the maintenance history of an aircraft because it provides a comprehensive record of all maintenance activities performed on the aircraft. This includes routine inspections, repairs, modifications, and any other work that has been conducted to ensure the aircraft remains airworthy and compliant with regulatory standards. The logbook serves as an official document, which not only helps maintain the aircraft's safety and operational reliability but also meets legal and regulatory requirements. This information is crucial for both aircraft operators and regulatory authorities, as it allows for the tracking of maintenance intervals and assists in assessing the overall condition of the aircraft over time.

In contrast, other documents listed serve different purposes. The flight manual contains operational information and limitations for pilots but does not focus on maintenance history. The technical specification sheet provides information about the aircraft's design and performance features but does not track the maintenance activities. Service bulletins are issued by manufacturers to convey important information about repairs or parts but do not function as a comprehensive maintenance record.