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Marking a propeller before removal

Aviation Mechanic Powerplant (AMP) practice question 6 of 10 on Propellers. ACS element AM.III.M.K6 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONA mechanic removes a dynamically balanced propeller that will be reinstalled on the same engine. How are the matching orientation marks made on the hub and engine flange?

  1. AWith a metal scribe
  2. BWith a chisel-point steel punch
  3. CWith a felt-tipped pen
Show the answer and explanation

Correct answer: C. With a felt-tipped pen

  • A — incorrect A scribe cuts into the surface and creates a stress riser; the procedure allows a felt-tipped pen only.
  • B — incorrect Punching leaves a permanent indentation in the hub, which the procedure does not allow; only a felt-tipped pen mark is permitted.
  • C — correct The removal procedure specifies an identifying mark made with a felt-tipped pen only on the propeller hub, with a matching mark on the engine flange, so the original orientation is restored and dynamic imbalance is prevented.

BACKGROUND

Propeller removal and installation must always follow current manufacturer information. In a representative removal procedure, the spinner dome is removed, any safety wire on the mounting studs is cut away, and the propeller assembly is supported with a sling. If the propeller has been dynamically balanced and will be reinstalled, an identifying mark is made with a felt-tipped pen only on the propeller hub and a matching mark on the engine flange, so that the same orientation can be restored and dynamic imbalance avoided. On installation the engine and propeller flanges are cleaned, dowel studs are aligned with the corresponding holes, and the mounting nuts are installed dry and torqued evenly to avoid hub damage.

STUDY TIP

Remember that anything that scratches, gouges, or indents a propeller hub is prohibited for marking, and that mounting hardware is installed clean and dry.

KEY POINTS

  • Orientation marks on a dynamically balanced propeller are made with a felt-tipped pen only.
  • The hub mark is matched by a mark on the engine flange to restore orientation.
  • Mounting hardware is kept clean and dry, and nuts are tightened evenly to avoid hub damage.

SOURCES

  • sources/amp-powerplant/ch07.txt "Removal"
  • sources/amp-powerplant/ch07.txt "Installation"
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MORE ON PROPELLERS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.