FAA Aviation Mechanic General (AMG)Aircraft Drawings, Weight and BalanceHard
A technician completes a major repair on an aircraft and recalculates the empty weight CG at 83.2 inches aft of datum. The type certificate data sheet lists the empty weight CG range as 78.0 to 82.0 inches aft of datum. What action is required before the aircraft can be returned to service?
- AThe reference datum must be relocated so that the new CG falls within the printed empty weight CG range
- BBallast must be added or equipment relocated to bring the empty weight CG back within the specified range
- CThe empty weight CG range only applies during flight loading calculations, so no corrective action is needed
- DNone; the aircraft is airworthy as long as the loaded CG falls within the gross weight CG envelope
Show answer & explanationAnswer & explanation
Correct answer: B. Ballast must be added or equipment relocated to bring the empty weight CG back within the specified range
The empty weight CG range ensures that, across all approved loading conditions, the loaded CG will remain within limits. If the empty weight CG falls outside this range, corrective action such as adding/relocating ballast or equipment is required before further flight, regardless of where a particular loaded CG might fall.
Why the other options are wrong
- A. The datum is a fixed reference point defined by the manufacturer and cannot simply be moved to make numbers fit.
- C. The empty weight CG range is a fundamental limit that must be met for the aircraft's basic configuration, not just for flight loading.
- D. An out-of-range empty weight CG must be corrected even if one particular loading happens to fall within limits; other loadings could exceed limits.
Empty Weight CG Range
A specified range of CG locations, published for many small aircraft, within which the empty weight CG must fall to guarantee the loaded CG stays within limits across all approved loading conditions.
- Published in the TCDS or aircraft flight manual for some aircraft
- If empty weight CG falls outside range, corrective action is mandatory
- Prevents out-of-limit loaded CG under standard loading arrangements
Memory trick: Empty weight CG range is the 'safety zone' guaranteeing every load stays legal.