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7.14 HOVER CHART.
a.
The primary use of the chart (Figures 7-4 through 7-5) is illustrated by part A of the example. To determine the torque required to hover, it is necessary to know pres-sure altitude, free air temperature, gross weight, and desired wheel height. Enter the upper right grid at the known free air temperature, move right to the pressure altitude, move down to gross weight. For OGE hover, move left to the torque per engine scale and read torque required. For IGE hover, move left to desired wheel height, de.ect down and read torque required for dual-engine or single-engine op-eration. The IGE wheel height lines represent a compro-mise for all possible gross weights and altitude conditions. A small torque error up to 63% torque may occur at ex-treme temperature and high altitude. This error is more evi-dent at lower wheel heights.

b.
In addition to the primary use, the hover chart (Figure 7-4) may be used to predict maximum hover height. To determine maximum hover height, it is necessary to know pressure altitude, free air temperature, gross weight, and maximum torque available. Enter the known free air tem-perature move right to the pressure altitude, move down to gross weight, move left to intersection with maximum torque available and read wheel height. This wheel height is the maximum hover height.

c.
The hover chart may also be used to determine maxi-mum gross weight for hover at a given wheel height, pres-sure altitude, and temperature as illustrated in method B of

the example (Figure 7-4). Enter at known free air tempera-
ture, move right to the pressure altitude, then move down and establish a vertical line on the lower grid. Now enter lower left grid at maximum torque available. Move up to wheel height, then move right to intersect vertical line from pressure altitude/FAT intersection. Interpolate from gross weight lines to read maximum gross weight at which the helicopter will hover.
7.15 EFFECTS OF BLADE EROSION KIT.
With the blade erosion kit installed, it will be necessary to make the following corrections. Multiply the torque re-quired to hover determined from the charts by 1.02. (Ex-ample: If indicated torque is 90%, multiply 90 x 1.02 = 91.8% actual torque required.) Multiply the maximum gross weight to hover obtained from the charts by 0.98. (Ex-ample: If gross weight is 22,000 lb, multiply by 0.98 = 21,560 lb actual gross weight to hover.) When determining maximum hover wheel height, enter the chart at 1.02 x gross weight. (Example: If gross weight is 20,000 lb, mul-tiply 20,000 x 1.02 = 20,400 lb).
7.16 EFFECTS OF ADDITIONAL INSTALLED EQUIPMENT.
To determine maximum gross weight to hover, multiply chart value by .995. For maximum hover height or torque required to hover, enter chart at a value of 1.005 multiplied by the gross weight.
EXAMPLE A
WANTED: 
TORQUE REQUIRED TO HOVER OGE AND AT A 10-FOOT WHEEL HEIGHT 
KNOWN: 
FAT = 30°C PRESSURE ALTITUDE = 2,000 FEET GROSS WEIGHT = 19,500 POUNDS 
METHOD: 
ENTER HOVER CHART AT KNOWN FAT. MOVE RIGHT TO PRESSURE ALTITUDE, MOVE DOWN THROUGH GROSS WEIGHT LINES TO DESIRED GROSS WEIGHT. MOVE LEFT TO INDICATE TORQUE/ENGINE % (OGE) SCALE AND READ OGE HOVER TORQUE (94%). MOVE DOWN FROM INTERSECTION OF 10-FOOT HOVER LINE AND HORIZONTAL LINE TO READ TORQUE REQUIRED TO HOVER 10 FEET (80%). 
EXAMPLE B 
WANTED: 
MAXIMUM GROSS WEIGHT TO HOVER OGE 
KNOWN: 
ATF = 1.0 FAT = 15°C PRESSURE ALTITUDE = 8,000 FEET MAXIMUM TORQUE AVAILABLE = 96% 
METHOD: 
ENTER INDICATED TORQUE/ENGINE (IGE) SCALE AT MAXIMUM TORQUE AVAILABLE (96%), MOVE UP TO OGE LINE. ENTER CHART AT KNOWN FAT (15°C). MOVE RIGHT TO PRESSURE ALTITUDE LINE (8,000 FT). MOVE DOWN FROM PRESSURE ALTITUDE LINE AND MOVE RIGHT FROM OGE LINE. WHERE LINES INTERSECT, READ MAXIMUM GROSS WEIGHT TO HOVER OGE. 
Figure 7-4. Hover -Clean Con.guration (Sheet 1 of 2) 
　
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