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## Determining the CG in Percentage of Mean Aerodynamic Chord (Percent MAC) 

This procedure is the same as found in Chapter 5, Single- Engine Aircraft Weight and Balance Computations. Refer to the load conditions and CG information found in Figures 7-5, 7-6,  and 7-7  to compute the CG in percent MAC: 

The loaded CG is +36.4 inches aft of the datum. 

The MAC is 58.0 inches long. 

 The leading edge mean aerodynamic chord (LEMAC) is located at station 25.98. 

The CG is +36.4 – 25.98 = 10.42 inches aft of LEMAC. 

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Use the formula in Figure 7-8  to determine CG in MAC percentages. 

<img src='content_image/556215.jpg'>

The loaded CG after alteration or repair is located at 17.9 percent MAC. 

## Empty Weight CG (EWCG) Range 

The fuel tanks, seats, and baggage compartments of some aircraft are so located that changes in the fuel or occupant load have a very limited effect on the balance of the aircraft. Aircraft of such a configuration show an empty weight CG (EWCG) range in the Type Certificate Data Sheet (TCDS). If the EWCG is located within this range, it is impossible to legally load the aircraft so that its loaded CG falls outside its allowable range. 

If the TCDS lists an EWCG range, and after the alteration is completed the EWCG falls within this range, then there is no need to compute a fore and aft check for adverse loading. But if the TCDS lists the EWCG range as “None” (and most of them do), a check must be made to determine whether or not it is possible by any combination of legal loading to cause the aircraft CG to move outside of either its forward or aft limits. 

## Adverse-Load CG Checks 

Many modern aircraft have multiple rows of seats and often more than one baggage compartment. After any repair or alteration that changes the weight and balance, the Airframe and Powerplant (A&P) FAA-certificated mechanic or repairman must ensure that no legal condition of loading can 

