Text in force at CS25-28: from CS25-3, effective 19 Sep 2007.
(See CS-P 530 and CS-P 550.)
(a) The magnitude of the propeller blade vibration stresses under any normal condition of operation must be determined by actual measurement or by comparison with similar installations for which these measurements have been made.
(b) The determined vibration stresses may not exceed values that have been shown to be safe for continuous operation.
ED Decision 2007/010/R · Source