When replacing a component during maintenance, which information should be documented in the maintenance log?

• A. Only the date of replacement.
• B. Only the part number.
• C. Part number and serial; replacement date.
• D. Part number, serial, lot or batch, replacement date, and any calibration or test results.

Answer: (D)

Maintaining complete traceability for maintenance actions is the key idea. When a component is replaced, you want a record that not only shows what was installed but also when and how it performed afterward. Documenting the part number identifies the exact component type and revision, which is essential for compatibility and future ordering. The serial number provides a unique identifier for the specific unit installed, helping track that exact part through the system’s history and against any warranty or defect notices. Including the lot or batch number adds production-level traceability, which can be crucial if a broader quality issue emerges with a particular production run. Recording the replacement date marks when the maintenance occurred, supporting maintenance scheduling, warranty windows, and service history. Finally, capturing any calibration or test results confirms the component is operating within specifications after installation, and provides evidence that the system was verified as ready for service.

Documents that only note a date miss the component identity, while only listing a part number misses the specific unit and timing details. Including the part number and serial with the date covers basic identity and timing, but still leaves out batch information and any post-replacement performance verification, which are important for full traceability and assurance.