SECTION V. HOVER

TM 1-1520-240-10 7-5-1 SECTION V. HOVER 7-5-1. Description. The hover chart, figure 7-5-1, presents torque required to hover at 100% RRPM at various combinations of PA, FAT, GW, and wheel height for single and dual engine operation. 7-5-2. Use of Chart. a. The primary use of the charts is illustrated by the example. To determine the torque required to hover, it is necessary to know PA, FAT, GW, and desired wheel height. Enter the upper right grid at the known pressure altitude, move right to the temperature, move down to gross weight. Move left to desired wheel height, deflect down and read torque required for dual engine or single engine operation. b. n addition to the primary use, the hover ceiling charts (fig. 7-5-2) may be used to predict maximum hover height. This information is necessary for use of the takeoff chart found in figure 7-6-1. To determine maximum hover height, it is necessary to know PA, FAT, GW, and maximum torque available. Enter at the known pressure altitude, move right to FAT, 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 charts may also be used to determine maximum GW for hover at a given wheel height, PA, and temperature. Enter at known pressure altitude, move right to the FAT, then move down to the bottom of the lower grid, and read density altitude. Now enter lower left grid at maximum torque available. Move up to wheel height, then move right to density altitude and read GW. This is the maximum gross weight at which the helicopter will hover. 7-5-3. Conditions. a. The hover chart is based on calm wind, level surface, and 100% RRPM. b. Hover in ground effect (HIGE) data is based on hovering over a level surface. For normal transition from hover to forward flight, the minimum hover wheel height should be 10 feet to prevent ground contact. If helicopter is to hover over a surface known to be steep, covered with vegetation, or if type of terrain is unknown, the flight should be planned for hover out of ground effect (HOGE) capability. c. EAPS installation has negligible effect on hover torque figure 7-5-1. d. Hover ceiling charts, figure 7-5-2, with EAPS installed, reduce gross weight by 700 pounds.