# 14 CFR § 27.307: Proof of structure

> Federal · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/ecfr-14-27.307

## Section

- **Citation:** 14 CFR § 27.307
- **Heading:** Proof of structure
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** September 22, 2026
- **Source:** Publisher's official text
- **Location:** Title 14—Aeronautics and Space > CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION > SUBCHAPTER C—AIRCRAFT > PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT > Subpart C—Strength Requirements > General

## Text

(a) Compliance with the strength and deformation requirements of this subpart must be shown for each critical loading condition accounting for the environment to which the structure will be exposed in operation. Structural analysis (static or fatigue) may be used only if the structure conforms to those structures for which experience has shown this method to be reliable. In other cases, substantiating load tests must be made.
(b) Proof of compliance with the strength requirements of this subpart must include—
(1) Dynamic and endurance tests of rotors, rotor drives, and rotor controls;
(2) Limit load tests of the control system, including control surfaces;
(3) Operation tests of the control system;
(4) Flight stress measurement tests;
(5) Landing gear drop tests; and
(6) Any additional test required for new or unusual design features.
(Secs. 604, 605, 72 Stat. 778, 49 U.S.C. 1424, 1425)
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as amended by Amdt. 27-3, 33 FR 14105, Sept. 18, 1968; Amdt. 27-26, 55 FR 7999, Mar. 6, 1990]

## Nearby sections

- [14 CFR § 27.301 § 27.301 Loads.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.301.md)
- [14 CFR § 27.303 § 27.303 Factor of safety.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.303.md)
- [14 CFR § 27.305 § 27.305 Strength and deformation.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.305.md)
- [14 CFR § 27.307 § 27.307 Proof of structure.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.307.md)
- [14 CFR § 27.309 § 27.309 Design limitations.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.309.md)
- [14 CFR § 27.321 § 27.321 General.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.321.md)
- [14 CFR § 27.337 § 27.337 Limit maneuvering load factor.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.337.md)
- [14 CFR § 27.339 § 27.339 Resultant limit maneuvering loads.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.339.md)
- [14 CFR § 27.341 § 27.341 Gust loads.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.341.md)
- [14 CFR § 27.351 § 27.351 Yawing conditions.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.351.md)
- [14 CFR § 27.361 § 27.361 Engine torque.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.361.md)
- [14 CFR § 27.391 § 27.391 General.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.391.md)
- [14 CFR § 27.395 § 27.395 Control system.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.395.md)
- [14 CFR § 27.397 § 27.397 Limit pilot forces and torques.](https://www.frixlaw.com/law-library/statutes/ecfr-14-27.397.md)

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/ecfr-14-27.307. Check the current official text before relying on it. Not legal advice.