FAR 23.2550 — High-Energy Rotors
FAR 23.2550 requires equipment with high-energy rotors to be designed or installed to protect occupants and the airplane from uncontained fragments.
FAR 23.2550 is a Part 23 airworthiness rule for small airplane design. It addresses any onboard equipment containing high-energy rotors — think items like turbine engines, auxiliary power units (APUs), air cycle machines, and certain pumps or generators that spin at very high speeds and store significant rotational energy.
The rule requires that this equipment be either:
- Designed so that, if a rotor fails, fragments are contained within the equipment itself, or
- Installed in a location and orientation that protects the occupants and the airplane from any uncontained fragments that escape.
Why it matters operationally: a high-energy rotor that fails can throw shrapnel-like fragments at lethal speeds, potentially puncturing the cabin, fuel tanks, or critical flight controls. By the time you, as a pilot, are flying the airplane, this protection has already been engineered in during certification — but understanding the rule helps you appreciate why certain equipment is mounted where it is and why uncontained failures are treated as a serious airworthiness concern.