(a) Turbine engine operating characteristics must be investigated in
flight to determine that no adverse characteristics(suchasstall,surge,of
flameout) are present, to a hazardous degree, during normal and emergency
operation within the range of operating limitations of the rotorcraft and
of the engine.
(b) The turbine engine air inlet system may not, as a result of airflow
distortion during normal operation, cause vibration harmful to the engine.
(c) For governor-controlled engines, it must be shown that there exists
no hazardous torsional instability of the drive system associated with
critical combinations of power, rotational speed, and control