If the TCDS list an empty-weight CG 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-Loaded 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 A&P mechanic or repairman must ensure that no
legal condition of loading can move the CG outside of its
allowable limits. To determine this, adverse-loaded CG
checks must be performed and the results noted in the
weight and balance revision sheet.
Figure 5-4.
Weight and moment index changes caused by a typical alteration.
allowable range.