FAA Federal Aviation Regulations (FARS, 14 CFR)

(a) No loss of normal propeller pitch control may cause hazardous overspeeding of the propeller under intended operating conditions.

(b) Each pitch control system that is within the propeller, or supplied with the propeller, and that uses engine oil for feathering, must incorporate means to override or bypass the normally operative hydraulic system components so as to allow feathering if those components fail or malfunction.

(c) Each propeller approved for installation on a turbopropeller engine must incorporate a provision for an indicator to indicate when the propeller blade angle is below the flight low pitch position. The provision must directly sense the blade position and be arranged to cause an indicator to indicate that the blade angle is below the flight low pitch position before the blade moves more than 8° below the flight low pitch stop.

[Amdt. 35-2, 32 FR 3737, Mar. 4, 1967, as amended by Amdt. 35 -- 5, 45 FR 60182, Sept. 11, 1980]