9-6 Determining the Correct Stabilizer Trim Setting Determining CG Changes Caused by  Modifying the Cargo Effects of Loading or Offloading Cargo Figure 9-12.  Determining thelocation ofCG in inches beforecargo  is removed. Figure 9-9.  Stabilizer trim setting in ANU units. Figure 9-11.  Determining the location of CG in percent MAC. Figure 9-10.  Determining the distance from CG to the LEMAC. It is important before takeoff to set the stabilizer trim for the  existing CG location. There are two ways the stabilizer trim  setting systems may be calibrated: in percent MAC and in  units airplane nose up (ANU).  If the stabilizer trim is calibrated in percent MAC, determine  the CG location in percent MAC as has just been described,  then set the stabilizer trim on the percentage figure thus  determined. Some aircraft give the stabilizer trim setting in  units of ANU that correspond with the location of the CG  in percent MAC. When preparing for takeoff in an aircraft  equipped with this system, first determine the CG in percent  MAC in the way described above, then refer to the stabilizer  trim setting chart on the takeoff performance page of pertinent AFM.  Figure 9-9  is an excerpt from the AFM chart  on the takeoff performance of a Boeing 737. Since large aircraft can carry substantial cargo, adding,  subtracting, or moving any of the cargo from one hold to  another can cause large shifts in the CG.  Both the weight and CG of an aircraft are changed when  cargo is loaded or offloaded. In the following example, the  new weight and CG are calculated after 2,500 pounds of  cargo is offloaded from the forward cargo hold Aircraft specifications are Consider an airplane with these specifications CG location................................................ station 635.7 LEMAC ........................................................ station 625 MAC .................................................................. 134.0 in Refer to  Figure 9-9  for all flap settings and a CG located  at 8 percent MAC; the stabilizer setting is 7 3 ⁄4 units ANU. LEMAC ................................................... station 549.13 MAC .................................................................. 141.5 in Forward cargo hold centroid...................... station 352.1 Weight change ................................................... 2,500 lb Loaded CG........................................ 22.5 percent MAC Loaded weight ................................................. 90,000 lb 1.  Determine the CG location in inches from the  datum before the cargo is removed. Do this by first determining the distance of the CG aft of the LEMAC.  [Figure 9-12] 1.  Determine the distance from the CG to the LEMAC  by using the formula in  Figure 9-10 . 2.  Determine the location of the CG in percent MAC by  using the formula found in  Figure 9-11 . Distance CG to LEMAC = Datum to CG – Datum to LEMAC = 10.7 inches = 635.7 – 625 ( ) CG in % MAC = × 100 Distance CG to LEMAC MAC ( ) = × 100 10.7 134.0 = 8.0 % MAC ( ) CG (inches aft of LEMAC) = × MAC CG in % MAC 100 ( ) = × 141.5 22.5 100 = 31.84 inches Stabilizer Trim Setting—Units Airplane Nose Up 6 8 10 12 14 16 18 20 22 24 26 28 30 32 8 7 3 /4 7 1 /2 7 6 3 /4 6 1 /4 5 3 /4 5 1 /2 5 4 1 /2 4 3 1 /2 3 2 1 /2 Flaps (all) CG