AMC E 790(a)(1) Rain and Hail Ingestion Certification for Design
Changes and Derivative Engines – Turbine Engine Power/Thrust Loss and
Instability in Extreme Conditions of Rain and Hail
ED
Decision 2018/014/R
CS-E 790(a)(1) allows,
as an alternative to conducting a full Engine test, the certification of
design changes or derivative Engines based on alternative evidence provided by
the applicant (such as other Engine test(s), rig test(s), analysis, or an
appropriate combination of these); however, alternative evidence is not
intended to be used for the certification of new Engines.
Any parametric analysis used to substantiate design changes or derivative Engines should fall within a 10 % variation in the critical impact parameter (CIP) that was used to substantiate the original base Engine. The CIP(s) is (are) often associated with the impact load at the point of contact between the hail and the rotor blade. This is generally a function of the impact speed, the rotor speed, and the blade twist angle. This 10 % variation in the CIP(s) should not be assumed to be a direct tolerance on the applicant’s proposed changes to the Take-off Power or to the thrust ratings themselves.
[Amdt No: E/5]
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