CS 25.361 Engine and auxiliary power unit torque
ED Decision 2009/017/R
(See AMC 25.361)
(a) For engine installations:
(1) Each engine mount, pylon and adjacent supporting airframe structures must be designed for the effects of –
(i) A limit engine torque corresponding to take-off power/thrust and, if applicable, corresponding propeller speed, acting simultaneously with 75% of the limit loads from flight condition A of CS 25.333(b);
(ii) A limit engine torque corresponding to the maximum continuous power/thrust and, if applicable, corresponding propeller speed acting simultaneously with the limit loads from flight condition A of CS 25.333(b); and
(iii) For turbo-propeller installations only, in addition to the conditions specified in subparagraphs (a)(1)(i) and (ii), a limit engine torque corresponding to take-off power and propeller speed, multiplied by a factor accounting for propeller control system malfunction, including quick feathering, acting simultaneously with 1 g level flight loads. In the absence of a rational analysis, a factor of 1·6 must be used.
(2) The limit engine torque to be considered under sub-paragraph (1) must be obtained by:
(i) for turbo-propeller installations, multiplying mean engine torque for the specified power/thrust and speed by a factor of 1·25.
(ii) for
other turbine engines, the limit engine torque must be equal to the maximum
accelerating torque for the case considered.
(3) The
engine mounts, pylons, and adjacent supporting airframe structure must be
designed to withstand 1g level flight loads acting simultaneously with the
limit engine torque loads imposed by each of the following conditions to be
considered separately:
(i) sudden
maximum engine deceleration due to a malfunction or abnormal condition; and
(ii) the maximum acceleration of the engine.
(b) For
auxiliary power unit installations:
The power unit
mounts and adjacent supporting airframe structure must be designed to
withstand 1g level flight loads acting simultaneously with the limit torque
loads imposed by the following conditions to be considered separately:
(1) sudden
maximum auxiliary power unit deceleration due to malfunction or abnormal
condition or structural failure; and
(2) the
maximum acceleration of the auxiliary power unit.
[Amdt 25/8]
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