AMC 27.45 Performance General

• ED Decision 2018/015/R found in: CS-27 Amdt 10 - Small Rotorcraft (Feb 2023)

AMC 27.45 Performance General ED Decision 2018/015/R15/R This AMC provides further guidance and acceptable means of compliance to supplement FAA AC 27-1B Change 7 AC 27.45. § 27.45 PERFORMANCE – GENERAL which is the EASA acceptable means of compliance, as provided for in [AMC 27 General](#_DxCrossRefBm8893777). However, some aspects of the FAA AC are deemed by EASA to be at variance with EASA’s interpretation or its regulatory system. EASA’s interpretation of these aspects is described below. Paragraphs of FAA AC 27.45. § 27.45 that are not amended below are considered to be EASA acceptable means of compliance. [...] b. Procedures [...] (7) Engine Failure Testing Considerations (i) For all tests used to investigate the behaviour of the rotorcraft following an engine failure, the failure of the engine is usually simulated in some way. When engines are controlled with a hydro-mechanical governing system, it is common practice to close the throttle quickly to idle. For rotorcraft equipped with engine electronic control systems, and particularly those with a 2-minute/30-second OEI rating structure, it is common practice to simulate an OEI condition by using reduced power on all engines by means of a flight test tool. (ii) In every case, it must be demonstrated that all aspects of rotorcraft and powerplant behaviour are identical to those that would occur in the event of an actual engine failure with the remaining engine developing minimum-specification power. Of particular concern are ‘dead engine’ power decay characteristics, ‘live engine’ acceleration characteristics, and rotor RPM control. (iii) To this end, it is expected that a number of actual engine shut down tests will be conducted to generate sufficient data to validate the fidelity of the flight test tool and methodology, which will then allow its use in developing regulatory performance data. In general, it is best to conduct the tests in a low hover with the rotorcraft stabilised below the HV low point. An engine is then shut down and, following the appropriate pilot intervention time, the collective control is raised to cushion the landing. [Amdt No: 27/6] AMC 27.45 Performance General ED Decision 2018/015/R15/R This AMC provides further guidance and acceptable means of compliance to supplement FAA AC 27-1B Change 7 AC 27.45. § 27.45 PERFORMANCE – GENERAL which is the EASA acceptable means of compliance, as provided for in [AMC 27 General](#_DxCrossRefBm472493219). However, some aspects of the FAA AC are deemed by EASA to be at variance with EASA’s interpretation or its regulatory system. EASA’s interpretation of these aspects is described below. Paragraphs of FAA AC 27.45. § 27.45 that are not amended below are considered to be EASA acceptable means of compliance. [...] b. Procedures [...] (7) Engine Failure Testing Considerations (i) For all tests used to investigate the behaviour of the rotorcraft following an engine failure, the failure of the engine is usually simulated in some way. When engines are controlled with a hydro-mechanical governing system, it is common practice to close the throttle quickly to idle. For rotorcraft equipped with engine electronic control systems, and particularly those with a 2-minute/30-second OEI rating structure, it is common practice to simulate an OEI condition by using reduced power on all engines by means of a flight test tool. (ii) In every case, it must be demonstrated that all aspects of rotorcraft and powerplant behaviour are identical to those that would occur in the event of an actual engine failure with the remaining engine developing minimum-specification power. Of particular concern are ‘dead engine’ power decay characteristics, ‘live engine’ acceleration characteristics, and rotor RPM control. (iii) To this end, it is expected that a number of actual engine shut down tests will be conducted to generate sufficient data to validate the fidelity of the flight test tool and methodology, which will then allow its use in developing regulatory performance data. In general, it is best to conduct the tests in a low hover with the rotorcraft stabilised below the HV low point. An engine is then shut down and, following the appropriate pilot intervention time, the collective control is raised to cushion the landing. [Amdt No: 27/6]