Density Altitude; Ige And Oge Hover Ceilings - Bell BHT-206L3-FM-1 LongRanger-III Flight Manual

FAA APPROVED
performance data contained in this manual
can be achieved.
If actual torque indication is less than the
required chart torque, engine power is less
than minimum specification and all
performance data contained in this manual
cannot be achieved. Refer to the
appropriate maintenance manual to
determine cause of low power.
4-2. DENSITY ALTITUDE
A Density Altitude Chart (figure 4-2) is
provided to aid in calculation of
performance and limitations. Density
altitude (Hp) is an expression of the density
of the air in terms of height above sea
level; hence, the less dense the air, the
higher the density altitude. For standard
conditions of temperature and pressure,
density altitude is the same as pressure
altitude (HP). As temperature increases
above standard for any altitude, the
density altitude will also increase to values
higher than pressure altitude. Figure 4-2
expresses density altitude as a function of
pressure altitude and temperature.
The chart also includes the inverse of the
which is used to calculate KTAS by the
relation:
If the ambient temperature is -15°C and the
pressure altitude is 6000 feet, find the
for 100 KCAS.
Solution:
a. Enter the bottom of the chart at -15°C.
b. Move vertically upward to the 6000 foot
pressure altitude line.
c. From this point, move horizontally to the
left and read a density altitude of 4000 feet
BHT-206L3-FM-1
and move horizontally to the right and
1.06 = 106 KTAS.
4-3. IGE AND OGE HOVER
CEILINGS
NOTE
Hover performance charts are
based on 100% ROTOR RPM.
I
The Hover Ceiling - In Ground Effect
charts (figure 4-3) and Hover Ceiling -
Out Of Ground Effect charts (figure 4-4)
present hover performance (allowable
gross weight) for conditions of pressure
altitude and OAT. Each chart is divided
into two areas.
AREA A (unshaded area) as shown on the
hover ceiling charts presents hover
performance for which satisfactory
stability and control has been
demonstrated in relative winds of 26 knots
(30 MPH) sideward and rearward at all
loading conditions.
NOTE
Engine TOT will rise noticeably
when hovering downwind. Avoid
hovering downwind when
operating near TOT limits.
Tail rotor control margin and/or
control of engine temperature
(TOT) may preclude operation in
AREA B of the hover ceiling
charts when the relative wind is in
the CRITICAL WIND AZIMUTH
AREA.
AREA B (shaded area) as shown on hover
ceiling charts presents additional hover
performance which can be achieved in
CALM WINDS or winds outside the
CRITICAL RELATIVE WIND AZIMUTH
AREA. Refer to figure 4-5.
4-5