Purpose and definition

This regulation introduces Subpart O of Part 91, which applies to operators of certain large or turbine-powered multiengine airplanes. It establishes the fundamental requirement that operators must actively support their aircraft's continued airworthiness throughout its service life.

In practical terms, this means you can't simply follow a static maintenance program. You must stay current with evolving airworthiness requirements, which may include:

• Updating your inspection program as manufacturers or the FAA issue new guidance
• Incorporating mandatory design changes when required
• Adopting revisions to the manufacturer's Instructions for Continued Airworthiness (ICA)

This is the foundation for the more specific requirements that follow in Subpart O. It matters because modern aircraft require ongoing attention to emerging safety issues, service bulletins, and airworthiness directives. The regulation makes clear that maintaining airworthiness is a continuous, evolving responsibility rather than a one-time compliance task.

*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.*