FAR 23.2230 — Limit and Ultimate Loads
FAR 23.2230 defines limit and ultimate loads for Part 23 aircraft, including the 1.5 factor of safety used in structural design.
In Plain English
FAR 23.2230 sets the basic structural load definitions an applicant must use when certifying a Part 23 airplane. It establishes two load levels the airframe must be designed and analyzed against:
- Limit loads — These are equal to the structural design loads unless another section of Part 23 says otherwise. Think of limit load as the maximum load expected in normal service; the structure must handle it without permanent deformation.
- Ultimate loads — These equal the limit loads multiplied by a 1.5 factor of safety, unless specified otherwise elsewhere in Part 23. The structure must be able to carry ultimate loads without failure (though some deformation is acceptable).
Why it matters operationally: this 1.5 safety margin is the reason airplanes can briefly exceed normal limits without breaking, and it's why pilots are taught to respect published G limits and maneuvering speeds. Exceeding limit load can damage the airframe; exceeding ultimate load can break it.
Regulation Text
14 CFR § 23.2230§ 23.2230 Limit and ultimate loads.
The applicant must determine—
(a) The limit loads, which are equal to the structural design loads unless otherwise specified elsewhere in this part; and
(b) The ultimate loads, which are equal to the limit loads multiplied by a 1.5 factor of safety unless otherwise specified elsewhere in this part.
Oral Exam Questions a DPE Might Ask
Q1What is the difference between limit load and ultimate load under Part 23?
Per FAR 23.2230, limit loads equal the structural design loads, while ultimate loads equal the limit loads multiplied by a 1.5 factor of safety, unless Part 23 specifies otherwise.
Q2What factor of safety does FAR 23.2230 require between limit and ultimate loads?
FAR 23.2230(b) requires a 1.5 factor of safety — ultimate loads are 1.5 times the limit loads unless otherwise specified in Part 23.
Q3Who is responsible for determining the limit and ultimate loads for a Part 23 airplane?
Under FAR 23.2230, the applicant for certification is responsible for determining both the limit loads and the ultimate loads for the airplane.
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Related Sections in Part 23