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. 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]
EASA rotorcraft performance regulations require demonstrating safe operation after engine failure. Flight test tools simulating engine failures are acceptable, but must accurately replicate real-world engine behavior, including power decay, engine acceleration, and rotor RPM control. Actual engine shutdown tests are needed to validate simulation fidelity, especially for electronic engine controls.
* Summary by Aviation.Bot - Always consult the original document for the most accurate information.
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