FAR 23.2310 — Seaplane Buoyancy Requirements
FAR 23.2310 sets buoyancy standards for seaplanes and amphibians, requiring 80% excess buoyancy and stability against capsizing if a float or hull floods.
In Plain English
FAR 23.2310 is an airworthiness standard that applies to airplanes designed to operate on water — that means seaplanes and amphibians certified under Part 23. It sets the minimum buoyancy the manufacturer must build into the floats or hull so the airplane stays safely on the surface.
The rule has two parts:
- 80% excess buoyancy: The floats or hull must provide buoyancy that is 80 percent greater than what is needed to support the airplane's maximum weight in fresh water. This margin accounts for rough conditions, weight shifts, and minor leaks.
- Flooding margin: The airplane must have enough reserve so it will stay afloat at rest in calm water without capsizing if a float compartment or hull section experiences a likely flooding event.
Why it matters operationally: as a seaplane pilot, you're trusting that a damaged float won't immediately sink or roll the airplane. This regulation is the design backstop — but you still need to inspect float compartments preflight and pump them out as required.
Regulation Text
14 CFR § 23.2310§ 23.2310 Buoyancy for seaplanes and amphibians.
Airplanes intended for operations on water, must—
(a) Provide buoyancy of 80 percent in excess of the buoyancy required to support the maximum weight of the airplane in fresh water; and
(b) Have sufficient margin so the airplane will stay afloat at rest in calm water without capsizing in case of a likely float or hull flooding.
Oral Exam Questions a DPE Might Ask
Q1What buoyancy margin does a Part 23 seaplane have to be designed with, and in what water conditions?
Per FAR 23.2310(a), the airplane must provide buoyancy that is 80 percent in excess of the buoyancy required to support the airplane's maximum weight in fresh water.
Q2If one of your float compartments floods, what does the certification standard guarantee about the airplane's behavior?
FAR 23.2310(b) requires that the airplane have sufficient margin to stay afloat at rest in calm water without capsizing in the event of a likely float or hull flooding.
Q3Which airplanes does FAR 23.2310 apply to?
FAR 23.2310 applies to airplanes certified under Part 23 that are intended for operations on water — that is, seaplanes and amphibians.
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Related Sections in Part 23