14 CFR § 27.49

For helicopters—

The hovering ceiling must be determined over the ranges of weight, altitude, and temperature for which certification is requested, with—

Takeoff power;

The landing gear extended; and

The helicopter in-ground effect at a height consistent with normal takeoff procedures; and

The hovering ceiling determined under paragraph (a)(1) of this section must be at least—

For reciprocating engine powered helicopters, 4,000 feet at maximum weight with a standard atmosphere;

For turbine engine powered helicopters, 2,500 feet pressure altitude at maximum weight at a temperature of standard plus 22 °C (standard plus 40 °F).

The out-of-ground effect hovering performance must be determined over the ranges of weight, altitude, and temperature for which certification is requested, using takeoff power.

For rotorcraft other than helicopters, the steady rate of climb at the minimum operating speed must be determined over the ranges of weight, altitude, and temperature for which certification is requested, with—

Takeoff power; and

The landing gear extended.