When should an aircraft be reweighed?

• A. After a flight to verify weight.
• B. After any maintenance, nothing changes.
• C. After an extensive repair or alteration that could change its weight or center of gravity.
• D. When removing the landing gear.

Answer: (C)

Reweighing is needed whenever changes to the aircraft could affect its weight or balance. The weight and balance calculations depend on the aircraft’s basic empty weight and its moments, so if you perform repairs or alterations that add, remove, or relocate mass, the empty weight and center of gravity will shift. Weighing the aircraft again and updating the data ensures that loading, fuel, payload, and trim calculations remain accurate and safe for flight.

Routine maintenance that doesn’t change weight or balance isn’t required to reweigh, and reweigh isn’t something you do after every flight just because fuel is burned. However, any extensive repair or alteration that could change weight or center of gravity—such as major component replacements, structural repairs, or significant modifications—mandates reweighing to keep the weight-and-balance data valid. Removing landing gear would be such an alteration and would necessitate reweighing for the same reason.