Decel Check

[Skidz]

Silly question:

 

Can someone share some technical notes on the decel check for these turbines ?

 

Thanks !

[heliskiguide]

From 100% N2 briskly roll throttle off, decel should be 3 to 5 seconds through 65% N1

 

For more detail than that you could talk to an engineer or consult the maintenance manual unless someone here has more to add.

[Max Continuous]

From 100% N2 briskly roll throttle off, decel should be 3 to 5 seconds through 65% N1

 

For more detail than that you could talk to an engineer or consult the maintenance manual unless someone here has more to add.

 

 

As above but also check for hunting of the N1 when it hits the flight idle range.

Max

[Skidz]

Thanks guys, that part was pretty clear. If memory serves, it's got to be done no less than 1 minute after N2 = 100%, right ?

 

It's just that I remember doing a much more complex decel check a couple years ago with an AME during I think a 500 hour inspection (could be wrong there). I vaguely remember a primary decel check, followed by a secondary decel check with a specific lapse of time before each check. If decel is too quick, gotta do it with gen off, etc etc.

[heliskiguide]

Did another decel check with an instructor once to check decel with engine loaded prior to practising autos. Bring machine light on skids, about 70% TOR depending on GW, then do decel check. If the decel is too fast/slow don't try an auto, AME needs to look at it.

[Coastal]

Hmmmmm. I'm on a machine right now (an L3) that might be going through 65% N1 a little too quickly. It's taking about 2 'mississippis' to get from 80% N1 (full throttle) through 65% N1. From what I understand, 3-5 seconds is the ideal range. More than 5 bad, less than 2 really bad. Anyone care to comment further?

[Skidz]

Have your wrench look at it. Could be something as benign as coking, or much worse...

[skullcap]

On C20 it is usually the rigging on governor more times than not. jwih