Low-oxygen hazard
Nitrogen-enriched air can create an oxygen-deficient atmosphere. Treat personnel exposure as a real hazard, not just a performance issue.
Use this as a refresher
Place the idea inside the full system chain: source/input → control → physical response → sensing/indication → consumer/result. If the quick note seems to conflict with the aircraft in front of you, stop and confirm configuration, effectivity and current approved data.
Maintenance boundary: this is a study reminder, not a task instruction.