FAR 23.2235 — Structural Strength
FAR 23.2235 sets structural strength rules for Part 23 airplanes: support limit loads without deformation and withstand ultimate loads. Student pilot guide.
In Plain English
FAR 23.2235 establishes the basic structural strength requirements that small airplanes certified under Part 23 must meet. The structure has to be strong enough to handle two distinct load categories:
- Limit loads — the maximum loads expected in normal service. The airframe must support these without:
- Interfering with the safe operation of the airplane (controls, systems, and handling must remain functional), and
- Causing detrimental permanent deformation (the structure can flex, but it must return to shape).
- Ultimate loads — typically 1.5× limit loads. The structure must support these without breaking, even though permanent deformation is acceptable at this level.
Why it matters operationally: As a pilot, this is the rule behind your airplane's published load factor limits (the G-limits in your POH). Staying within those limits keeps you in the limit-load envelope, where the airframe is guaranteed safe and undamaged. Exceeding them pushes you toward ultimate loads — and beyond that, structural failure.
Regulation Text
14 CFR § 23.2235§ 23.2235 Structural strength.
The structure must support:
(a) Limit loads without—
(1) Interference with the safe operation of the airplane; and
(2) Detrimental permanent deformation.
(b) Ultimate loads.
Oral Exam Questions a DPE Might Ask
Q1What two load levels must a Part 23 airplane's structure be able to support?
Per FAR 23.2235, the structure must support both limit loads (without unsafe interference or detrimental permanent deformation) and ultimate loads.
Q2At limit load, what two conditions must the structure avoid?
FAR 23.2235(a) requires that at limit loads the structure must not interfere with the safe operation of the airplane and must not suffer detrimental permanent deformation.
Q3Why are published G-limits in the POH important relative to FAR 23.2235?
The POH G-limits represent the limit loads the airframe is certified to handle under FAR 23.2235; staying within them ensures the structure remains safe and free of permanent deformation.
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Related Sections in Part 23