Management of Weight and Balance Control  Title 14 of the Code of Federal Regulations (14 CFR) part 23,  section 23.23 requires establishment of the ranges of weights  and CGs within which an aircraft may be operated safely. The  manufacturer provides this information, which is included in  the approved AFM, TCDS, or aircraft specifications.  While there are no specified requirements for a pilot operating  under 14 CFR part 91 to conduct weight and balance  calculations prior to each flight, 14 CFR part 91, section  91.9 requires the pilot in command (PIC) to comply with the  operating limits in the approved AFM. These limits include  the weight and balance of the aircraft. To enable pilots to  make weight and balance computations, charts and graphs  are provided in the approved AFM.  Weight and balance control should be a matter of concern to  all pilots. The pilot controls loading and fuel management  (the two variable factors that can change both total weight  and CG location) of a particular aircraft. The aircraft owner  or operator should make certain that up-to-date information  is available for pilot use, and should ensure that appropriate  entries are made in the records when repairs or modifications  have been accomplished. The removal or addition of  equipment results in changes to the CG.  Weight changes must be accounted for and the proper  notations made in weight and balance records. The  equipment list must be updated, if appropriate. Without such  information, the pilot has no foundation upon which to base  the necessary calculations and decisions.  Standard parts with negligible weight or the addition of minor  items of equipment such as nuts, bolts, washers, rivets, and  similar standard parts of negligible weight on fixed-wing  aircraft do not require a weight and balance check. The  following criteria for negligible weight change is outlined  in Advisory Circular (AC) 43.13-1 (as revised), Methods  Techniques and Practices—Aircraft Inspection and Repair:  The pilot should be familiar with the appropriate terms  regarding weight and balance. The following list of terms  and their definitions is standardized, and knowledge of these  terms aids the pilot to better understand weight and balance  calculations of any aircraft. Terms defined by the General  Aviation Manufacturers Association (GAMA) as industry  standard are marked in the titles with GAMA.  14 CFR part 125 requires aircraft with 20 or more seats  or maximum payload capacity of 6,000 pounds or more  to be weighed every 36 calendar months. Multi-engine  aircraft operated under 14 CFR part 135 are also required  to be weighed every 36 months. Aircraft operated under 14  CFR part 135 are exempt from the 36 month requirement  if operated under a weight and balance system approved in  the operations specifications of the certificate holder. For  additional information on approved weight and balance  control programs for operations under parts 121 and 135,  reference the current edition of AC 120-27, Aircraft Weight  and Balance Control. AC 43.13-l, Acceptable Methods,  Techniques and Practices—Aircraft Inspection and Repair  also requires that the aircraft mechanic ensure that the weight  and balance data in the aircraft records is current and accurate  after a 100-hour or annual inspection.  Before any flight, the pilot should determine the weight  and balance condition of the aircraft. Simple and orderly  procedures based on sound principles have been devised  by the manufacturer for the determination of loading  conditions. The pilot uses these procedures and exercises  good judgment when determining weight and balance. In  many modern aircraft, it is not possible to fill all seats,  baggage compartments, and fuel tanks, and still remain within  the approved weight and balance limits. If the maximum  passenger load is carried, the pilot must often reduce the fuel  load or reduce the amount of baggage.  Negligible CG change is any change of less than 0.05 percent  Mean Aerodynamic Chord (MAC) for fixed-wing aircraft  or 0.2 percent for rotary wing aircraft. MAC is the average  distance from the leading edge to the trailing edge of the  wing. Exceeding these limits would require a weight and  balance check.  • One pound or less for an aircraft whose weight empty  is less than 5,000 pounds  • Two pounds or less for aircraft with an empty weight  of more than 5,000 pounds to 50,000 pounds  • Five pounds or less for aircraft with an empty weight  of more than 50,000 pounds  •  Arm (moment arm)—the horizontal distance in inches  from the reference datum line to the CG of an item.  The algebraic sign is plus (+) if measured aft of the  datum and minus (–) if measured forward of the datum.  •  Basic empty weight (GAMA)—the standard empty  weight plus the weight of optional and special  equipment that have been installed.  •  Center of gravity (CG)—the point about which an  aircraft would balance if it were possible to suspend it  at that point. It is the mass center of the aircraft or the  theoretical point at which the entire weight of the aircraft  is assumed to be concentrated. It may be expressed in  inches from the reference datum or in percent of MAC.  The CG is a three-dimensional point with longitudinal,  lateral, and vertical positioning in the aircraft.  Terms and Definitions  10-4 