FAA Aviation Mechanic General (AMG)Aircraft Drawings, Weight and BalanceMedium
A large transport-category aircraft is being weighed using jacks because platform scales cannot be positioned under the main landing gear. Which precaution is most important during this jack weighing procedure?
- ALeave the landing gear struts fully compressed to obtain a consistent reading
- BFill all fuel tanks to their standard tank capacity before beginning the weighing
- CWeigh only the nose gear jack point since it supports the reference datum
- DRaise the aircraft on jacks until the wheels are just clear of the floor, keep the aircraft level, and read the load cells at each jack point
Show answer & explanationAnswer & explanation
Correct answer: D. Raise the aircraft on jacks until the wheels are just clear of the floor, keep the aircraft level, and read the load cells at each jack point
When weighing on jacks, the aircraft must be raised until the wheels/tires are just clear of the ground, leveled per the manufacturer's leveling points, and the load at each jack point read from calibrated load cells; all jack points must be included to determine total weight and CG.
Why the other options are wrong
- A. Strut compression state does not need to be fully compressed; leveling and clearing wheels are the key requirements.
- B. Weighing is normally performed with a known, minimal or drained fuel condition per the weighing procedure, not full tanks.
- C. All jack points must be weighed and summed; using only the nose point would give an incomplete and incorrect total weight.
Jack Weighing
A method of weighing large aircraft using calibrated jacks and load cells at each designated jack point when platform scales cannot be used under the gear.
- Aircraft is raised until wheels clear the ground
- Aircraft must be leveled at manufacturer's leveling points
- Load cells at each jack point are summed for total weight and CG
Memory trick: Jack it up just enough to float free, then level and read every point.