Prop protective systems Flash Cards

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Title: Prop protective systems
Description: Prop protective systems P3
Number of Cards: 40
Save Count: 0
Author: ndbarber9
Created: 2012-01-03
Tags: 114
Private No

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    • Question
    • Answer
    • Side 3
    • Acronym for Prop Protective Devices?
    • BBAPPLAND
    • What are the Prop protective devices?
    • B - Brake(prop)
      B - Beta Followup
      A - Autofx
      P - Pichlock
      P - Pichlock reset
      L - Low pitch stop
      A - 45 deg Airstart protection
      N - NTS
      D - Decoupple
    • Decouple - What it does
    • If NTS fail, Decouple prevents excessive negative TRQ and DRAG
    • Decouple - How?
    • Physically disconnects prop/gearbox from the engine
    • Decouple - When?
    • -500 to -1700 SHP
      should have worked by -1700SHP
    • Indications of decouple?
    • SHP = 0
      RPM = 100%, unless caused by ovrspd
      TIT = 550 unless flameout
      FF = 600 ish pph unless flameout
    • 45 deg air start protection - What it does
    • Prevent rapid RPM increase & neg trq if NTS fails
    • 45 deg air start protection - How?
    • Powers Fx vlv sol to hydr move fx-valve to fx --> incr. bladeangle
    • 45 deg air start protection - When?
    • When fx button is held out, PCO not pressed & blade angle is 45 deg or finer
    • 45 deg air start protection - indications?
    • Accompanied by flashing NTS INOP light on vertical ann panel
    • Beta followup, what it does and why
    • To prevent excessive drag if NTS etc fail at high power settings;

      -Programs minimum blade angle at each power setting in the alpha range
    • Beta followup - when?
    • In flightrange
    • Beta followup - minimum blade angle range from flight idle to __ coord?
    • 11 deg angle FLT IDLE to 68 deg coord
    • Beta followup - minimum blade angle between __ and __ coord?
    • Between 68 deg and 88 - from 11 to 22.5 at 88 coord
    • Pitchlock - What?
    • Prevents excessive overspeed
    • Pitchlock - How?
    • Pitchlock teeth come together to prevent decrease in blade angle during overspeed. If there is controlling oil in the prop then blade angle can increase.
    • Pitchlock - When?
    • RPM exceeds 103.5% rpm,
      or a loss of prop fluid
    • Pitchlock - cammed out?
    • Above 57 deg blade angle to allow unfeather

      Below 17 deg blade angle to prevent pitchlock during reverse
    • Pitchlock reset - what?
    • Prevents pitchlock during rapid reverse
    • Pitchlock reset - how?
    • Resets pitchlock actucation speed to 109%

      -instead of the 103.5% normally pitchlock actuation-speed
    • Pitchlockreset - when?
    • Blade angle above 10 deg & Pwrlev below 28 coord
    • Pitchlock - other nots?
    • OVSPD above 103.5% rpm in reverse are normal and could cause pitchlock if blade angl is abv 17 deg...

      Pitchlock reset prevents this until 109% rpm
    • NTS - what?
    • Prevent prop from driving engine
    • NTS - how?
    • Mech moves fx vlv to fx, incr blade angl to overcome negative torque
    • NTS - when?
    • When negative trq is
      -100 to -500 SHP (ENG 2&3 inborad)
      -150 to -500 SHP (ENG 1&4 outboard)
    • NTS - cammed out when?
    • Below 24 deg COORD
    • NTS - notes
    • Prop will NTS until neg trq is overcome

      On restart, CTM, balanced by NTS walks blade out of fx to stabilized RPM of about 35% rpm
    • Autofx
      (Thrustsensetive system) - what?
    • Provides Auto-fx at takeoff
    • Autofx
      (Thrustsensetive system) - how?
    • Thrust sensetive plunger engages a switch assy pulling in the fx button
    • Autofx
      (Thrustsensetive system) - when?
    • Armed
      More than 60 coord or more
      Less than 500 SHP
      No other Fx'd
    • Autofx
      (Thrustsensetive system) - How many props can autofeather?
    • One - the first cuts out the others
    • Autofx
      (Thrustsensetive system) - priority?
    • 4-1-3-2
      Right to Left, Out and In
    • Low pitch stop - what?
    • Limits blade angle in flight mech to 13 deg
    • Low pitch stop - how?
    • Thee latch-type levers supported by a wedge that must be retracted in order for blade angle to decr below 13 deg
    • low pitch stop - when?
    • ALPHA range, blade increased to above 13 deg
    • low pitch stop - notes?
    • Through the rotation of cams on the alpha and beta shafts; these cannot be broken until an appropriate time, as when on the ground on landing rollout
    • Prop brake - what?
    • Prevents prop from windmilling when Fx'd and decreases rundown time when eng secured.
    • Prop brake - how?
    • Within RGB assy and as part of accessories drive train, slows the speed at which these turn
    • Prop brake - when?
    • When RPM below 21% rpm
      or prop starts to rotate backward
    • prop brake - positions and when?
    • RELEASED - RPM abv 21%,
      or starter trq applied

      APPLIED - RPM below 21%

      LOCKED - when prop starts to rotate backwards