CSP
−
E
−
1
Performance Data
ROTORCRAFT FLIGHT MANUAL
MD 500E
(Model 369E)
Revision 14
5
−
27
FAA Approved
5
−
8. POWER CHECK
−
ROLLS ROYCE 250
−
C20R/2
The Power Check Chart shows the relationship of engine torque, turbine outlet
temperature, and horsepower at various conditions of pressure altitude and
OAT for an Rolls Royce 250−C20R/2 engine producing specification power as
installed in the MD 500E helicopter. The primary purpose of this chart is its
use as an engine performance trending tool to aid in determining whether the
engine is producing specification power, or if engine power deterioration has
occurred.
NOTE
:
Power check data taken at regular intervals should be plotted to monitor trends
in engine condition. See Allison 250
−
C20 Series operational and Maintenance
Manual for additional information on trend analysis.
The C20R/2 Power Check Chart is based on the same conditions as the C20B
Power Check Chart. First, an adjustment to the OAT should be made before
entering the chart (add 2.5
°
C if the data was taken in a hover or 1
°
C if the
data was taken in forward flight). The second change is the addition of ‘‘Accel-
eration Bleed Valve Open’’ lines to the chart; any reflection of data that falls
below the appropriate dashed altitude reference line should be disregarded as
it may involve a partially open engine accelerating bleed valve.
NOTE
:
If a mist eliminator is installed, subtract 5
°
C from the TOT read during flight
before comparing it with the specification TOT.
Example 1:
WANTED:
Check engine performance
DATA OBTAINED DURING FLIGHT:
Torque
= 87.2 psig
TOT
= 750
°
C
PA
= 1000 feet
OAT
= 19
°
C
Specification TOT (from chart): 755
°
C
Compare the specification TOT of 755
°
C with the TOT observed during
flight (750
°
C for this example). The TOT that wasobserved is lower than
the specification TOT. If the TOT observed had been higher than the speci-
fication TOT read from the chart, some power deterioration will have oc-
curred and the performance data given in this manual may not be obtained.
