AA.I.A.K3FAA-S-ACS-11A · Nov 2023Knowledge

Propellers–type, controls, feathering/unfeathering, auto-feather, negative torque sensi...

ACS element text (the applicant demonstrates understanding of)

Propellers–type, controls, feathering/unfeathering, auto-feather, negative torque sensing, synchronizing, synchrophasing, and thrust reverse, including uncommanded reverse procedures.

Bottom line

The pilot of a typical multiengine airplane can feather the propeller of an inoperative engine, and feathering minimizes propeller drag by stopping engine rotation with the blade streamlined with the relative wind. An uncommanded or inadvertent deployment of thrust reversers while airborne is an emergency. Reverse thrust is more effective at high speed than at low speed, so the pilot should use it as soon as is prudent after touchdown.

Key numbers

Key numbers for Propellers–type, controls, feathering/unfeathering, auto-feather, negative torque sensi...
NumberWhat it means
parasite drag as great as the entire airframe's, for a propeller windmilling at high speed in the low range of blade anglesWindmill drag
two types on a jet engine: target or cascadeReverser types

FAA references

  1. AFH ch. 13 (pp. 13-3–13-5) — FAA-H-8083-3C
  2. AFH ch. 16 (pp. 16-10–16-11) — FAA-H-8083-3C
  3. PHAK ch. 2 (p. 2-20) — FAA-H-8083-25C (2023)
  4. PHAK Glossary — FAA-H-8083-25C (2023)
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