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Citation X's and ASE

moonlight

Flyin' to fund my fishin'
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I was in ASE the other day on a drop off, and was standing on the ramp as a X took off. It made a loud, rhythmic popping noise as it accelerated down the runway, and I thought I was watching a jet shuck a motor. In talking to another pilot, he mentioned that he'd heard it before there at ASE, but only from X's. Anyone else heard this or know what is the underlying reason for it?
 

ProFracPilot

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I have several friends who fly X's, and I'm told the APU's are wont to burp. That's probably the sound you were hearing.
 

K.V.

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I have several friends who fly X's, and I'm told the APU's are wont to burp. That's probably the sound you were hearing.


I'm usually pretty good at figuring out what people are trying to say in their miss-types, but you've got me scratching my head on this one.
 

ProFracPilot

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It wasn't a mis-type.

wont


Pronunciation: \ˈwȯnt, ˈwōnt also ˈwənt, ˈwänt\
Function:adjective
1 : accustomed, used <got up early as he is wont to do>
2 : inclined, apt <revealing as letters are wont to be — Gladys M. Wrigley>
 

aveator

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guess you schooled him...mental note...word of the day,,wont.......
 

AA717driver

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He was just speaking "The Queen's English"...as he is wont to do. ;)

TC
 

NotFurloughed

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Apu

It was definitely the APU compressor stalling. Has happened to us at ASE and other high altitude airports.
 

cherry20's

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I was there the other day. What was the tail number? If it was one of XOJET's X's it wasn't the APU. It should have been off before takeoff... Would make sense that it could have been the APU.
 

Diesel

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APU.

We took off with the APU everytime.
 

X-rated

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I was there the other day. What was the tail number? If it was one of XOJET's X's it wasn't the APU. It should have been off before takeoff... Would make sense that it could have been the APU.

Cherry,

APU Shutdown is at the Captains discretion at XO. That's why the before Takeoff checklist says "as required", and APU also appears on the after takeoff checklist. When it is hot, I often leave it on for better cabin cooling, and for better engine performance out of places like ASE. I don't know if it was one of ours, but I'm pretty sure Dangerboy was hearing APU compressor stalls.
 

CRJFlyer

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I may be wrong but I'm pretty sure the APU does very little to help in cooling or performance, especially during T/O...(obviously on the ground, engines off it does everything)

Cabin air at high power settings is taken of LP air from the 8th stage.. Remember the HP/LP select valve closes when TL's are above 60degrees. Even on the ramp with engines started the air coming in is from the engines and HP 14th stage air...In max cool it may have a greater effect than turning the packs to HIGH, but right now I can't remeber if there is an increase in airflow or not.

APU has nothing to do with performance..

On the other hand, I think it's a great idea to have the APU on for T/O just for the sake of having a 3rd electrical back-up...just my .02
 
Last edited:

X-rated

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I may be wrong but I'm pretty sure the APU does very little to help in cooling or performance, especially during T/O...(obviously on the ground, engines off it does everything)

Cabin air at high power settings is taken of LP air from the 8th stage.. Remember the HP/LP select valve closes when TL's are above 60degrees. Even on the ramp with engines started the air coming in is from the engines and HP 14th stage air...In max cool it may have a greater effect than turning the packs to HIGH, but right now I can't remeber if there is an increase in airflow or not.

APU has nothing to do with performance..

On the other hand, I think it's a great idea to have the APU on for T/O just for the sake of having a 3rd electrical back-up...just my .02

I agree TOPI limits pressurization to 8th stage LP air for pressurization and therefore performance degradation is minimal, but every little bit helps. Also, the main reason I leave it on on hot days is for cabin cooling. The APU provides more flow to the pacs, and therefore cools the cabin better.
 

t-bone

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I agree TOPI limits pressurization to 8th stage LP air for pressurization and therefore performance degradation is minimal, but every little bit helps.

Sounds like someone just went to recurrent!!!
 

scangadah

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The popping you hear is the two pilots a$$ cheeks sucking up the seat cushions when trying to go all the way to KHPN/KBOS on a hot summer day.
 
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