14 CFR § 135.423 - Maintenance, preventive maintenance, and alteration organization.

---
identifier: "/us/cfr/t14/s135.423"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 135.423 - Maintenance, preventive maintenance, and alteration organization."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "135.423"
section_name: "Maintenance, preventive maintenance, and alteration organization."
chapter_name: "FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "G"
subchapter_name: "AIR CARRIERS AND OPERATORS FOR COMPENSATION OR HIRE: CERTIFICATION AND OPERATIONS"
part_number: "135"
part_name: "OPERATING REQUIREMENTS: COMMUTER AND ON DEMAND OPERATIONS AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 106(f), 40113, 41706, 44701-44702, 44705, 44709, 44711-44713, 44715-44717, 44722, 44730, 45101-45105; Pub. L. 112-95, 126 Stat. 58 (49 U.S.C. 44730)."
regulatory_source: "Docket 16097, 43 FR 46783, Oct. 10, 1978, unless otherwise noted."
cfr_part: "135"
---


# 135.423 Maintenance, preventive maintenance, and alteration organization.

(a) Each certificate holder that performs any of its maintenance (other than required inspections), preventive maintenance, or alterations, and each person with whom it arranges for the performance of that work, must have an organization adequate to perform the work.

(b) Each certificate holder that performs any inspections required by its manual under § 135.427(b) (2) or (3), (in this subpart referred to as *required inspections*), and each person with whom it arranges for the performance of that work, must have an organization adequate to perform that work.

(c) Each person performing required inspections in addition to other maintenance, preventive maintenance, or alterations, shall organize the performance of those functions so as to separate the required inspection functions from the other maintenance, preventive maintenance, and alteration functions. The separation shall be below the level of administrative control at which overall responsibility for the required inspection functions and other maintenance, preventive maintenance, and alteration functions is exercised.

[Docket 16097, 43 FR 46783, Oct. 10, 1978. Redesignated by Amdt. 135-81, 67 FR 72765, Dec. 6, 2002. Redesignated by Amdt. 135-81, 70 FR 5533, Feb. 2, 2005]