CSP
−
E
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1
ROTORCRAFT FLIGHT MANUAL
Performance Data
MD 500E
(Model 369E)
Revision 14
5
−
2
FAA Approved
5
−
2. DENSITY ALTITUDE
Description:
The chart allows a quick estimation of the density altitude when pressure
altitude and OAT are known. This chart should be used for determining
density altitude for use with gross weight limits for the HV Diagram and
speed for Best Rate of Climb Chart. This chart can also be used to deter-
mine true airspeed.
Use of Chart:
To determine density altitude, the pilot must know pressure altitude and
outside air temperature. Enter bottom of chart with known or estimated
OAT, move up to known pressure altitude line, move to left and note densi-
ty altitude.
NOTE
:
Pressure altitude is found by setting 29.92 (1013 mb) in kolsman window
±
altimeter error.
To determine true airspeed convert indicated airspeed (IAS) to calibrated
airspeed (CAS) utilizing the Airspeed Calibration Curve (Figure 5−2). Read
value on right of chart opposite known density altitude. Multiply CAS by
this value to determine true airspeed.
Examples:
Wanted
Find density altitude
Known
OAT= −15
°
C
H
P
= 6,000
Method
Follow −15
°
C line to 6,000 ft pressure altitude line; read density altitude
(3800 ft).
Wanted
Find TAS
Method
Read directly across from density altitude: (3800 ft). Note density factor
of 1.058.
1. Find calibrated airspeed (Ref. Figure 5−2)
2. Find true airspeed
130 KIAS = 130.5 KCAS
130.5 KCAS
1.058 = 138.1; round to 138 knots true airspeed.
