G-3 LEMAC.  Leading edge of the mean aerodynamic chord. A  reference point for measurements, and specified in inches  from the datum to allow computations to relate percent MAC  to the datum. Empty weight center of gravity (EWCG).  This is the center  of gravity of the aircraft in the empty condition, containing  only the items specified in the aircraft empty weight. This  CG is an essential part of the weight and balance record of  the aircraft. Empty weight center of gravity range.  The distance  between the allowable forward and aft empty-weight CG  limits. Load cell.  A componentinan electronicweighing systemthat  is placed between the jack and the jack pad on the aircraft.  Theloadcellcontains straingauges whoseresistancechanges  with the weight on the cell. Load factor.  The ratio of the maximum load an aircraft can  sustain to the total weight of the aircraft. Normal category  aircraft must have a load factor of a least 3.8; utility category  aircraft, 4.4; and acrobatic category aircraft, 6.0. Equipment list.  A list of items approved by the FAA for  installation in a particular aircraft. The list includes the name,  part number, weight, and arm of the component. Installation  or removal of an item in the equipment list is considered to  be a minor alteration. Loading graph.  A graph of load weight and load moment  indexes. Diagonal lines for each item relate the weight to the  moment index, eliminating the need for calculations. Fleet weight.  An average weight accepted by the FAA for  aircraft of identical make and model that have the same  equipment installed. When a fleet weight control program  is in effect, the fleet weight of the aircraft can be used rather  than requiring every individual aircraft to be weighed. Loading schedule.  A method of calculating and documenting  aircraft weight and balance prior to taxiing to ensure the  aircraft will remain within all required weight and balance  limitations throughout the flight Fuel jettison system.  A fuel subsystem that allows the fligh crew to dump fuel in an emergency to lower the weight of an  aircraft to the maximum landing weight if a return to landing  is required before sufficient fuel is burned off. This system  must allow enough fuel to be jettisoned that the aircraft can  still meet the climb requirements specified in 14 CFR part 25. Longitudinal axis.  An imaginary line through an aircraft  from nose to tail, passing through its center of gravity. Longitudinal balance. The balance around the pitch, or  lateral, axis. MAC.  Mean aerodynamic chord. Fulcrum.  The point about which a lever balances. Index point.  A location specified by the aircraft manufacturer  from which arms used in weight and balance computations  are measured. Arms measured from the index point are called  index arms. Major alteration. An alteration not listed in the aircraft,  aircraft engine, or propeller specifications (1) that might  appreciably affect weight, balance, structural strength,  performance, powerplant operation, flight characteristics,  or other qualities affecting airworthiness; or (2) that is not  done according to accepted practices or cannot be done by  elementary operations. Interpolate. Determine a value in a range between two  known values. Maximum landing weight.  (GAMA) The maximum weight  approved for the landing touchdown. Landing weight.  The takeoff weight of an aircraft minus the  fuel burned and/or dumped en route. Large aircraft (14 CFR part 1).  An aircraft of more than  12,500 pounds maximum certificated takeoff weight Maximum permissible hoist load.  The maximum external  load that is permitted for a helicopter to carry. This load is  specified in the POH Lateral balance.  The balance around the roll, or longitudinal,  axis. Lateral offset moment.  The moment, in pound inches, of a  force that tends to rotate a helicopter about its longitudinal  axis. The lateral offset moment is the product of the weight of  the object and its distance from butt line zero. Lateral offset  moments that tend to rotate the aircraft clockwise are positive,  and those that tend to rotate it counterclockwise are negative. Maximum ramp weight.  (GAMA) The maximum weight  approved for ground maneuver. It includes weight of start,  taxi, and runup fuel. Maximum takeoff weight.  (GAMA) The maximum weight  approved for the start of the takeoff run.