 G-4 Maximum taxi weight. The maximum weight approved  for ground maneuvers. This is the same as maximum ramp  weight. Maximum weight.  The maximum authorized weight of  the aircraft and all of its equipment as specified in the Type  Certificate Data Sheets (TCDS) for the aircraft Maximum zero fuel weight. The maximum authorized  weight of an aircraft without fuel. This is the total weight  for a particular flight minus the fuel. It includes the aircraft  and everything that is carried on the flight except the weight  of the fuel. Mean aerodynamic chord (MAC).  The average distance  from the leading edge to the trailing edge of the wing. METO horsepower (maximum except takeoff HP).  The  maximum power allowed to be produced continuously by an  engine. Takeoff power is usually limited to a given amount  of time, such as 1 minute or 5 minutes. Minimum fuel.  The amount of fuel necessary for one-half  hour of operation at the rated maximum-continuous power  setting of theengine, which, for weightand balancepurposes,  is  1 ⁄12  gallon per maximum-except-takeoff (METO) horse- power. It is the maximum amount of fuel that could be used  in weight and balance computations when low fuel might  adversely affect the most critical balance conditions. To  determine the weight of the minimum fuel in pounds, divide  the METO horsepower by two. M inoralteration.  An alteration other than a major alteration.  This includes alterations that are listed in the aircraft, aircraft  engine, or propeller specifications Moment.  A force that causes or tends to cause an object to  rotate. It is indicated by the product of the weight of an item  multiplied by its arm. Moment.  (GAMA) The product of the weight of an item  multiplied by its arm. (Moment divided by a constant is used  to simplify balance calculations by reducing the number of  digits; see reduction factor.) Moment index.  The moment (weight times arm) divided by  a reduction factor. Moment limits versus weight envelope.  An enclosed area on  a graph of three parameters. The diagonal line, representing  the moment/100, crosses the horizontal line, representing the  weight at the vertical line, representing the CG location in  inches aft of the datum. If the lines cross inside the envelope,  the aircraft is loaded within its weight and CG limits. Net weight.  The weight of the aircraft minus the weight of  chocks or other devices used to hold the aircraft on the scales. Normal category.  A category of aircraft certificat d under  14 CFR part 23 and CAR part 3 that allows the maximum  weight and CG range while restricting the maneuvers that  are permitted. PAX.  The abbreviation of passengers. Payload. (GAMA) The weight of occupants, cargo, and  baggage. Percent MAC.  The distance in inches of the CG from  LEMAC divided by the MAC. It is a good standard for CG  location in airplanes because it permits a standard weight and  balance program for different types of airplanes. Pilot’s operating handbook (POH). An FAA-approved  document published by the airframe manufacturer that lists  the operating conditions for a particular model of aircraft  and its engine(s). Potable water.  The water carried in an aircraft for the  purpose of drinking. Ramp weight.  The zero fuel weight plus all of the usable  fuel on board. Reference datum.  (GAMA) An imaginary vertical plane  from which all horizontal distances are measured for balance  purposes. Reduction factor.  A number, usually 100 or 1,000, by which  a moment is divided to produce a smaller number that is less  likely to cause mathematical errors when computing the  center of gravity. Residual fuel.  The fuel that remains trapped in the system  after draining the fuel from the aircraft with the aircraft in  level flight attitude. The weight of this residual fuel is counted  as part of the empty weight of the aircraft. Service ceiling.  The highest altitude at which an aircraft  can maintain a steady rate of climb of 100 feet per minute. Small aircraft (14 CFR part 1).  An aircraft weighing 12,500  pounds or less maximum certificated takeoff weight Standard empty weight.  (GAMA) The weight of a standard  airplane including unusable fuel, full operating fluids, and  full oil.