Maintenance and preventive maintenance personnel duty time limitations

This regulation requires Part 121 air carriers (and those performing maintenance for them) to give maintenance and preventive maintenance personnel mandatory rest time. Within the United States, these workers must receive at least 24 consecutive hours off duty during any seven-day period, or an equivalent amount of time off within a calendar month.

The rule aims to prevent fatigue among maintenance personnel, recognizing that tired mechanics pose safety risks just as fatigued pilots do. The "equivalent thereof within any one calendar month" language provides some scheduling flexibility—for example, allowing four days off in a 28-day month rather than strictly one day per week.

This applies specifically to maintenance work performed within U.S. borders for Part 121 operators. Certificate holders must track and enforce these duty time limits to ensure their maintenance staff get adequate rest between work periods.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*