Weight and Balance and Equipment Lists
The data chain
The TCDS establishes maximum weights, the datum, and the forward and aft CG limits, often expressed in inches from the datum and sometimes in percent of mean aerodynamic chord. The aircraft weight and balance report establishes empty weight, empty weight CG, and installed equipment. The equipment list is the inventory that supports that empty weight; alterations or equipment changes that shift weight or arm require a revised report and, for major alterations, Form 337 documentation.
Computation
The math is moments: weight times arm equals moment; total the weights and the moments, divide total moment by total weight for the loaded CG, and compare against the forward and aft limits for the applicable weight. Zero-fuel weight, maximum landing weight, and minimum fuel for weighing are frequent sources of error. Weight shifts move the CG by the amount of weight moved times the distance moved, divided by total weight.
Inspection points
During an annual inspection, verify the weight and balance report reflects what is actually installed, that the equipment list matches the aircraft, that required equipment is present and operative, that placards match the report, that permanent ballast is documented, and that the flight manual limits are aboard and legible.
Traps
Empty weight versus basic empty weight differ by included fluids. The CG envelope narrows at higher weights, so a legal forward loading at low weight may be illegal when heavy. Ballast added without documentation corrupts every subsequent calculation and is a recordkeeping discrepancy as well as an airworthiness one.
Rule of thumb
If you cannot trace installed equipment to the equipment list, the weight and balance report is unverified - treat it as a discrepancy until resolved.