TM 55-1510-221-10
Rate of Change in Fuel Flow = (30 Lbs/hr) ÷
(10°C)
Rate of Change in Fuel Flow = 3.0 Lbs/hr
decrease per 1°C increase
Temperature increase from ISA + 20°C to ISA
+ 27°C = 7°C
Total Change in Fuel Flow = 7 x 3.0 Lbs/hr =
21.0 Lbs/hr
Total Fuel Flow = (ISA + 20°C Fuel Flow) +
(Total Change in Fuel Flow)
Total Fuel Flow = (478) - (21) = 457 Lbs/hr
Reserve Fuel = 45 minutes x Total Fuel Flow
Reserve Fuel = (0.75) x (457 Lbs/hr) = 342.75
= 343 lbs.
Total Fuel Requirement = 1781 + 343 = 2124
pounds
7-14. ZERO FUEL WEIGHT LIMITATION.
For this example, the following conditions were
assumed:
Ramp Weight
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12,090 pounds
Weight of Usable Fuel Onboard . . . . . .
2124 pounds
Zero Fuel Weight = Ramp Weight - Weight of
Usable Fuel Onboard
Zero Fuel Weight = (12,090) - (2124) = 9966
pounds
Maximum zero fuel weight limitation (from
LIMITATIONS section) = 11,500 pounds.
Maximum Zero Fuel Weight Limitation has not
been exceeded.
Anytime the Zero Fuel Weight exceeds the Max-
imum Zero Fuel Weight Limit, the excess must be
off-loaded from PAYLOAD. If desired, additional
FUEL ONLY may then be added until the ramp
weight equals the Maximum Ramp Weight Limit of
15.090 Lbs.
7-15. LANDING INFORMATION.
The estimated Landing Weight is determined by
subtracting the fuel required for the trip from the
Ramp Weight:
Ramp Weight
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12,090 Lbs
Fuel Required for Total Trip
. . . . . . . . . .
1781 pounds
Landing Weight (12,090 - 1781) . . . . 10,309 pounds
Enter the NORMAL LANDING DISTANCE
WITHOUT PROPELLER REVERSING - FLAPS
100% Graph at 32°C, 4732 feet, 10,309 pounds, and
10 knots head wind component:
Ground
Roll
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1800 feet
Total Distance Over 50-foot Obstacle . . . . 2510 feet
Approach Speed
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
99 knots
Enter the CLIMB - BALKED LANDING Graph
at 32°C, 4732 feet, and 10,309 pounds:
Rate of Climb
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1270 ft/min
Climb
Gradient
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2%
7-16. COMMENTS PERTINENT TO THE USE OF
PERFORMANCE GRAPHS.
a .
In addition to presenting the answer for a
particular set of conditions the example on a graph
also presents the order in ‘which the various scales
on the graph should be used. For instance, if the
first item in the example is FAT, then enter the
graph at the existing FAT.
b.
The reference lines indicate where to begin
following the guidelines. Always project to the refer-
ence line first, then follow the guidelines to the next
known item by maintaining the same PROPOR-
TIONAL DISTANCE between the guide line above
and the guide line below the projected line. For
instance, if the projected line intersects the reference
line in the ratio of 30% down/70% up between the
guidelines, then maintain this same 30%/70% rela-
tionship between the guide lines and follow them to
the answer or next known item.
c. The associated conditions define the spe-
cific conditions from which performance parameters
have been determined. They are not intended to be
used as instructions; however, performance values
determined from charts can only be achieved if the
specified conditions exist.
d.
The full amount of usable fuel is available
for all approved flight conditions.
e.
Indicated airspeeds (IAS) were obtained
using the Airspeed Calibration - Normal System
graph.
f: Notes have been provided on various
graphs and tables to approximate performance with
ice vanes extended. The effect will vary, depending
upon airspeed, temperature, altitude, and ambient
conditions. At lower altitudes, where operation on
the torque limit is possible, the effect of ice vane
extension will be less, depending upon how much
power can be recovered after the ice vanes have
been extended.
7-6
