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Code of Federal Regulations (Last Updated: July 5, 2024) |
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Title 14 - Aeronautics and Space |
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Chapter I - Federal Aviation Administration, Department of Transportation |
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SubChapter C - Aircraft |
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Part 27 - Airworthiness Standards: Normal Category Rotorcraft |
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Subpart E - Powerplant |
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Rotor Drive System |
§ 27.939 - Turbine engine operating characteristics.
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§ 27.939 Turbine engine operating characteristics.
(a) Turbine engine operating characteristics must be investigated in flight to determine that no adverse characteristics (such as stall, surge, or 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 displacement.
[Amdt. 27-1, 32 FR 6914, May 5, 1967, as amended by Amdt. 27-11, 41 FR 55469, Dec. 20, 1976]