Maintenance, preventive maintenance, and alteration organization

This regulation ensures that Part 121 air carriers have adequate organizational structures for maintenance work. If a carrier performs its own maintenance, preventive maintenance, or alterations—or contracts this work to others—both the carrier and the contractor must have sufficient organization to handle the workload properly.

The key requirement involves required inspections (those mandated by the carrier's maintenance manual). When an organization performs both required inspections and other maintenance work, it must structurally separate these functions. Inspectors cannot report to the same immediate supervisor as the mechanics doing the actual maintenance work. This separation must occur below the administrative level where someone has overall responsibility for both functions.

This organizational separation creates checks and balances, preventing the same person or team from both performing maintenance and inspecting their own work. It's a fundamental quality control measure that helps ensure aircraft are properly maintained and inspected by independent eyes within the organization.

*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.*