REFLECTOR: Prop Cycling

[Scott Baker]

Cycling the propeller prior to take off verifies that the propeller control is working - and more importantly, introduces warm oil into the hydraulic hub.  The propeller governor actuation is designed to work (best) with warm oil.  As a proverbial "airport bum" and flight instructor, I've seen pilots use many methods of cycling hydraulic propellers, including a single "teasing" of the prop control (very little rpm drop) to "dragging" the engine rpm down as low as it will go.  Neither practice, it seems, causes harm to the engine.  My personal choice is to cycle the propeller twice, doing so at the normal run-up rpm, and allowing a 200 to 300 rpm drop, observing the oil pressure dropping and the manifold pressure rising, before pushing the prop control back in.  I look for a positive and smooth rpm drop response to pulling the prop control.  A two or three-second laps in response time is normal if the oil is cold - anything longer than that, especially if the oil is warm, is cause for mechanical examination.  I allow the engine rpm to stabilize before cycling the propeller the second or third time.
SB

  ----- Original Message ----- 
  From: Craig and/or Denise Woolston 
  To: 'Velocity Aircraft Owners and Builders list' 
  Sent: Thursday, September 07, 2006 9:23 AM
  Subject: REFLECTOR: Prop Cycling


  Okay another newbie checklist question.  How are most people cycling there prop during the run-up process.

   

  What RPM, how many times, how fast do you cycle it?  I found two different RPMs in the MT manual and I've heard of two different reasons to do it fast or slow.

   

  Thanks,

   

  Craig

  N541SW a "FLYING XL-5FG"

   



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