This document discusses auditing of quality assurance and engineering departments. It defines quality audit as an examination to determine compliance with plans and effectiveness in achieving objectives. It discusses the importance of quality maintenance in maintaining perfect equipment and products. The key pillars of quality maintenance are focused improvement, autonomous maintenance, planned maintenance, maintenance prevention, and training. Critical systems like HVAC, WFI, and ETP are also discussed. HVAC maintenance is important for temperature control, airflow, and preventing cross-contamination. Validation of these critical systems ensures the sterile area and systems operate as intended.