Text in force at 25-153: from 25-126, effective 23 Dec 2008.
(a) Each propeller must have a type certificate.
(b) Engine power and propeller shaft rotational speed may not exceed the limits for which the propeller is certificated.
[ (c) The propeller blade pitch control system must meet the requirements of Sec. Sec. 35.21, 35.23, 35.42 and 35.43 of this chapter.]
(d) Design precautions must be taken to minimize the hazards to the airplane in the event a propeller blade fails or is released by a hub failure. The hazards which must be considered include damage to structure and vital systems due to impact of a failed or released blade and the unbalance created by such failure or release.
73 FR 63345 · Source