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When to consider Jet engine Spooled down

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When to consider Jet engine Spooled down

Old 3rd Aug 2017, 14:33
  #1 (permalink)  
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Join Date: Dec 2012
Location: Buenos Aires
Age: 43
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When to consider Jet engine Spooled down

I fly an A320. At parking beacon was turned off as soon N1 reached 5% or had amber crosses. Now the FCOM changed to turn beacon off when engine has spooled down. I'm trying to find what is the exact meaning of spooled down, as soon as you switch it down? As soon as its stopped? N1, N2? When should a jet engine considered spooled down for safety issues?
fernando78 is offline  
Old 4th Aug 2017, 00:35
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Join Date: Mar 2002
Location: Florida
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I don't know if this is an engine alone issue or an aircraft issue.

My simple understanding is that if the engine is below start pressure (compressor spool speed + ram air), it's probably a safety issue unless you do something to pump more air into it.
lomapaseo is offline  
Old 4th Aug 2017, 04:03
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Join Date: Jun 1999
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When the noise stops it's safe to say it's safe...
ACMS is offline  
Old 4th Aug 2017, 04:41
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Join Date: Jun 2005
Location: USA
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Even if only windmilling in a 10 kt breeze, the fan is still dangerous to any pax or ground personnel who might choose to stick their head or other appendages in!

For the purposes of when it's safe for trained ground personnel to approach the inlet danger zone, 5 % either N1 or N2 and reducing was perfectly safe with the fuel cut off as far as getting pulled in is concerned. So are we to interpret "spooled down" to mean zero percent on paper, even though we know the fan may not reach a complete stop as long as it remains parked in the wind? That's a nonspecific term and should be changed back to the way it was or replaced with another number. Some office weenie with nothing more productive to do?
westhawk is offline  
Old 7th Aug 2017, 01:52
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Join Date: Dec 2001
Location: FL, USA
Posts: 2,751
Let's not overthink this one.
To me "spooled down" means it's below minimum start ( fuel ) N1 and deceleration trend.
Inadvertent grabbing of the wrong lever/switch and turning the fuel back on would not cause the engine to spool up again.

This does NOT necessarily mean the engine is safe for ground personnel.
B2N2 is online now  
Old 7th Aug 2017, 07:12
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Join Date: Mar 2005
Location: N/A
Posts: 4,094
Only ever flew turbine helos and was taught to monitor EGT until N1 was zero to ensure there wasn't an after fire internally, in which case you of course motor the engine hopefully to blow it out and contain EGT rise. Featured in the "Emergency" section of the manual.
megan is offline  

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