6.4.6.1 Engine operation on board under a specified
test cycle may not always be possible, but the test procedure, as
approved by the Administration, shall be as close as possible to the
procedure defined in 3.2. Therefore,
values measured in this case may not be directly comparable with test-bed
results because measured values are very much dependant on the test
cycle.
6.4.6.2 In the case of the E3 test cycle, if the
actual propeller curve differs from the E3 curve, the load point used
shall be set using the engine speed, or the corresponding mean effective
pressure (MEP) or mean indicated pressure (MIP), given for the relevant
mode of that cycle.
6.4.6.3 Where the number of measuring points on
board is different from those on the test bed, the number of measurement
points and the associated revised weighting factors shall be approved
by the Administration.
6.4.6.4 Further to 6.4.6.3 where the E2, E3 or
D2 test cycles are applied, a minimum of load points shall be used
of which the combined nominal weighting factor, as given in 3.2, is greater than 0.50.
6.4.6.5 Further to 6.4.6.3 where the C1 test cycle
is applied, a minimum of one load point shall be used from each of
the rated, intermediate and idle speed sections. If the number of
measuring points on board is different from those on the test bed,
the nominal weighting factors at each load point shall be increased
proportionally in order to sum to unity (1.0).
6.4.6.6 With regard to the application of 6.4.6.3,
guidance in respect of the selection of load points and revised weighting
factors is given in section 6 of appendix
8 of this Code.
6.4.6.7 The actual load points used to demonstrate
compliance shall be within ± 5% of the rated power at the modal
point except in the case of 100% load, where the range shall be +0
to –10%. For example, at the 75% load point the acceptable range
shall be 70% – 80% of rated power.
6.4.6.8 At each selected load point, except idle,
and after the initial transition period (if applicable), the engine
power shall be maintained at the load set point within a 5% coefficient
of variance (%C.O.V.) over a 10-minute interval. A worked example
of the coefficient of variance calculation is given in section 7 of appendix 8 of this Code.
6.4.6.9 Regarding the C1 test cycle, the idle
speed tolerance shall be declared, subject to the approval of the
Administration.