FAA Aviation Mechanic General (AMG)Aircraft Drawings, Weight and BalanceEasy
A structural repair manual lists a fuel quantity sensor location as 'WL 95.' What does this designation identify?
- AThe horizontal distance aft of the datum
- BThe lateral distance from the aircraft centerline
- CThe angular clock position around the fuselage
- DThe vertical distance above a horizontal reference plane
Show answer & explanationAnswer & explanation
Correct answer: D. The vertical distance above a horizontal reference plane
Water Line (WL) measures vertical distance, usually in inches, above a horizontal reference plane (often the ground or a point below the fuselage), used to locate components vertically on the aircraft.
Why the other options are wrong
- A. That describes Fuselage Station (FS), not Water Line.
- B. That describes Butt Line (BL), a lateral measurement.
- C. Aircraft location systems do not use clock positions for structural location.
Water Line (WL)
A location reference system that measures vertical distance, in inches, above (or occasionally below) a horizontal reference plane established by the manufacturer.
- Measured vertically, in inches
- Reference plane may be ground level or a fixed point below the aircraft
- Used with FS and BL to give a 3-D location on the aircraft
Memory trick: Water rises up, so Water Line goes UP the aircraft.