W&B 6-2

Figure 6-1. Typical weight and balance data for a light twin-engine airplane. Datum Forward face of fuselage bulkhead ahead of rudder pedals Seats 2 at 37.0 2 at 75.0 1 at 113.0: 200 lb limit Fuel 213.4 gal (2 wing tanks, 105.0 gal each 103.0 gal usable at +61.0) Undrainable fuel: 1.6 lb at +62 Oil 24 quarts (12 quarts in each engine): −3.3 Baggage Forward 100 lb limit : −15 Aft 200 lb limit: +113 CG Range (+38) to (+43.1) at 5,200 lb (+43.6) at 4,800 lb (+32) to (+43.6) at 4,300 lb or less Straight line variation between points given Engine 2 240-horsepower horizontally opposed engines Fuel burn: 24 gph for 65% cruise at 175 knots 29 gph for 75% cruise at 180 knots Datum Front seats +37 2nd seats +75 3rd seat or baggage limit 200 lb +113 Fuel +61 100 lb baggage −15 EWCG 35.28 32.0 43.6 CG limits MAC = 61.620.1 Figure 6-2. Twin-engine airplane weight and balance diagram. Item Weight (lb) (5,200 max.) Arm (in) Moment (lb-in) CG 120,093 51,240 11,840 23,250 −1,500 10,170 215,093 42.47 Airplane Fuel (140 gal) Front seat Row 2 seats Foward baggage Aft baggage Total 3,404 840 320 310 100 90 5,064 35.28 61.0 37.0 75.0 −15.0 113.0 x = Figure 6-3. Determining the loaded CG of the sample airplane in Figure 6-2. The airplane in this example was weighed to determine its basic empty weight (BEW) and empty weight center of gravity (EWCG). The weighing conditions and results are: Weight with fuel drained and oil full: Right wheel scales ........................1,084 lb, tare 8 lb Left wheel scales ..........................1,148 lb, tare 8 lb Nose wheel scales.......................1,202 lb, tare 14 lb Determine the Loaded CG First, add the weights indicated by the individual scales and then subtract the tare weights to determine the BEW. Next, using the BEW and EWCG, the loaded weight and CG of the aircraft can be determined with data from Figure 6-2, using a chart such as the one in Figure 6-3. The aircraft is loaded as shown: Fuel (140 gal) ................................................ 840 lb Front seats ..................................................... 320 lb Row 2 seats.................................................... 310 lb Forward baggage ........................................... 100 lb Aft baggage ..................................................... 90 lb Chart Method Using Weight, Arm, and Moments Make a chart showing the weight, arm, and moments of the airplane and its load.