JAR 27.1521 Powerplant limitations
(a) General. The powerplant limitations
prescribed in this paragraph must be established
so that they do not exceed the corresponding
limits for which the engines are type certificated.
(b) Take-off operation. The powerplant takeoff
operation must be limited by –
(1) The maximum rotational speed,
which may not be greater than –
(i) The maximum value
determined by the rotor design; or
(ii) The maximum value shown
during the type tests;
(2) The maximum allowable manifold
pressure (for reciprocating engines);
(3) The time limit for the use of the
power corresponding to the limitations
established in sub-paragraphs (b) (1) and (2) of
this paragraph;
(4) If the time limit in sub-paragraph
(b) (3) of this paragraph exceeds 2 minutes, the
maximum allowable cylinder head, coolant
outlet, or oil temperatures;
(5) The gas temperature limits for
turbine engines over the range of operating and
atmospheric conditions for which certification
is requested.
(c) Continuous operation. The continuous
operation must be limited by –
(1) The maximum rotational speed
which may not be greater than –
(i) The maximum value
determined by the rotor design; or
(ii) The maximum value shown
during the type tests;
(2) The minimum rotational speed
shown under the rotor speed requirements in
JAR 27.1509 (c); and
(3) The gas temperature limits for
turbine engines over the range of operating and
atmospheric conditions for which certification
is requested.
(d) Fuel grade or designation. The
minimum fuel grade (for reciprocating engines),
or fuel designation (for turbine engines), must be
established so that it is not less than that required
for operation of the engines within the limitations
in sub-paragraphs (b) and (c) of this paragraph.
(e) Turboshaft engine torque. For rotorcraft
with main rotors driven by turboshaft engines, and
that do not have a torque limiting device in the
transmission system, the following apply:
(1) A limit engine torque must be
established if the maximum torque that the
engine can exert is greater than –
(i) The torque that the rotor drive
system is designed to transmit; or
(ii) The torque that the main rotor
assembly is designed to withstand in
showing compliance with JAR 27.547 (e).
(2) The limit engine torque established
under sub-paragraph (e) (1) of this paragraph
may not exceed either torque specified in subparagraph
(e) (1) (i) or (ii) of this paragraph.
(f) Ambient temperature. For turbine
engines, ambient temperature limitations
(including limitations for winterization
installations, if applicable) must be established as
the maximum ambient atmospheric temperature at
which compliance with the cooling provisions of
JAR 27.1041 to 27.1045 is shown.
(g) Two and one-half minute OEI power
operation. Unless otherwise authorised, the use
of 2½-minute OEI power must be limited to
engine failure operation of multi-engine, turbinepowered
rotorcraft for not longer that 2½ minutes
after failure of an engine. The use of 2½-minute
OEI power must also be limited by –
(1) The maximum rotational speed,
which may not be greater than –
(i) The maximum value
determined by the rotor design; or
(ii) The maximum demonstrated
during the type tests;
(2) The maximum allowable gas
temperature; and
(3) The maximum allowable torque.
(h) Thirty-minute OEI power operation.
Unless otherwise authorised, the use of 30-minute
OEI power must be limited to multi-engine,
turbine-powered rotorcraft for not longer than
30 minutes after failure of an engine. The use of
30-minute OEI power must also be limited by –
(1) The maximum rotational speed
which may not be greater than –
(i) The maximum value
determined by the rotor design; or
(ii) The maximum value
demonstrated during the type tests;
(2) The maximum allowable gas
temperature; and
(3) The maximum allowable torque.
(i) Continuous OEI power operation.
Unless otherwise authorised, the use of
continuous OEI power must be limited to multiengine,
turbine-powered rotorcraft for continued
flight after failure of an engine. The use of
continuous OEI power must also be limited by –
(1) The maximum rotational speed,
which may not be greater than –
(i) The maximum value
determined by the rotor design; or
(ii) The maximum value
demonstrated during the type tests;
(2) The maximum allowable gas
temperature; and
(3) The maximum allowable torque.
(j) Rated 30-second OEI power operation.
Rated 30-second OEI power is permitted only on
multi-engine, turbine-powered rotorcraft, also
certificated for the use of rated 2-minute OEI
power, and can only be used for continued
operation of the remaining engine(s) after a
failure or precautionary shutdown of an engine. It
must be shown that following application of 30-
second OEI power, any damage will be readily
[detectable by the applicable inspections and]
other related procedures furnished in accordance
with paragraph A27.4 of Appendix A of this JAR–
27. The use of 30-second OEI power must be
limited to not more than 30 seconds for any
period in which that power is used, and by –
(1) The maximum rotational speed
which may not be greater than –
(i) The maximum value
determined by the rotor design: or
(ii) The maximum value
demonstrated during the type tests:
(2) The maximum allowable gas
temperature; and
(3) The maximum allowable torque.
(k) Rated 2-minute OEI power operation.
Rated 2-minute OEI power is permitted only on
multi-engine, turbine-powered rotorcraft, also
certificated for the use of rated 30-second OEI
power, and can only be used for continued
operation of the remaining engine(s) after a
failure or precautionary shutdown of an engine. It
must be shown that following application of
2-minute OEI power, any damage will be readily
[detectable by the applicable inspections and]
other related procedures furnished in accordance
with A27.4 of Appendix A of this JAR–27. The
use of 2-minute OEI power must be limited to not
more than 2 minutes for any period in which that
power is used, and by –
(1) The maximum rotational speed,
which may not be greater than –
(i) The maximum value
determined by the rotor design; or
(ii) The maximum value
demonstrated during the type tests;
(2) The maximum allowable gas
temperature; and
(3) The maximum allowable torque.
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