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Purpose of jack safety collars

Aviation Mechanic General (AMG) practice question 22 of 25 on Weight and Balance. ACS element AM.I.C.K9 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONWhile an aircraft is being raised on wing jacks, the safety collars are kept screwed down against the jack cylinders to

  1. Akeep the jack from sliding inward on spring steel landing gear
  2. Bprevent tilting if a jack loses hydraulic pressure
  3. Cdistribute the load over the jack pad in place of a stress plate
Show the answer and explanation

Correct answer: B. prevent tilting if a jack loses hydraulic pressure

  • A — incorrect Inward sliding of spring steel gear is a separate hazard when jacking at the wheel; collars protect against loss of jack pressure.
  • B — correct The handbook directs that safety collars be kept screwed down against the jack cylinder as the jacks are raised, to prevent the aircraft from tilting if one jack loses hydraulic pressure.
  • C — incorrect Stress plates or panels distribute weight over the jack pad; safety collars have a different job.

BACKGROUND

Many aircraft are weighed by jacking them and lowering them onto scales or load cells, and extra care is needed when raising an aircraft on jacks. The handbook's safety precautions include installing stress plates under the jack pads if the manufacturer specifies them, allowing no movement by anyone inside the aircraft while it is being jacked, placing the jacks straight under the jack pads before raising, and raising all jacks simultaneously. Safety devices are placed against the jack cylinder so the aircraft cannot tip if any jack loses pressure. Not all jacks have screw-down collars; some use drop pins or friction locks.

STUDY TIP

Tie each jacking precaution to its hazard: collars and locks guard against loss of jack pressure, simultaneous raising guards against slipping off the jacks.

KEY POINTS

  • Keep safety collars screwed down as the jacks go up.
  • They prevent tipping if a jack loses hydraulic pressure.
  • Some jacks use drop pins or friction locks instead of collars.

SOURCES

  • FAA-H-8083-30B ch06 "Jacking the Aircraft"
  • FAA-H-8083-30B ch06 "Safety Considerations"
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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.