Which information regarding PMA parts is NOT required to be marked?

The correct answer is that the serial number is not required to be marked on Parts Manufacturer Approval (PMA) parts. PMA parts are components that have been approved by the FAA for use as replacement parts for type-certificated products. The regulations stipulate certain markings that must be included on PMA parts to ensure their traceability and conformity to approved standards.

The type certificate number, part number, and manufacturer's trademark are defined requirements that provide information regarding the origin, management, and approval status of the parts. The part number is essential for identifying the specific component, while the type certificate number, if applicable, connects the part to its officially recognized design. The manufacturer's trademark helps in ascertaining the source of the part and indicates quality assurance from the manufacturer.

In contrast, while serial numbers are often used for tracking and warranty purposes, they are not mandated by the FAA for PMA parts. This allows for ease of manufacturing and replacement, especially in high-volume production environments, where stamping a unique serial number on every part could be impractical or unnecessary.