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Load cell sensing principle

Aviation Mechanic General (AMG) practice question 6 of 25 on Weight and Balance. ACS element AM.I.C.R2 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONThe electronic load cell in a platform scale senses the applied weight by means of

  1. Aa strain gauge whose resistance changes with the load
  2. Ba hydraulic piston whose pressure is read on a calibrated gauge
  3. Ca mechanical lever arm balanced against a sliding counterweight
Show the answer and explanation

Correct answer: A. a strain gauge whose resistance changes with the load

  • A — correct The handbook explains that inside the load cell is an electronic strain gauge that measures a proportional change in electrical resistance as the applied weight increases.
  • B — incorrect Electronic load cells use a strain gauge and produce an electrical signal, not hydraulic pressure.
  • C — incorrect Mechanical and analog scales of that kind have mostly been replaced by wireless and digital electronic systems.

BACKGROUND

Aircraft can be weighed with platform scales or with top-of-jack load cells. A platform scale sits level on the hangar floor and contains an electronic load cell that senses the applied weight and generates a corresponding electrical signal. Inside the load cell an electronic strain gauge measures a proportional change in electrical resistance as the weight increases; a cable or wireless link carries this to a display unit, computer, or tablet that converts the resistance change to pounds. Top-of-jack load cells work the same way, with a concave top that seats on the aircraft jack pad.

STUDY TIP

Remember that load cells convert weight to a resistance change through a strain gauge, and that leveling on jacks is done with the jacks while leveling on platforms requires deflating tires or struts.

KEY POINTS

  • Platform scales and top-of-jack load cells are the two weighing methods.
  • A strain gauge in the load cell changes resistance with load.
  • The display converts the electrical signal to pounds.

SOURCES

  • FAA-H-8083-30B ch06 "Weight and Balance Equipment - Scales"
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MORE ON WEIGHT AND BALANCE

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.