taguilo
Posts: 73
Joined: Tue Aug 02, 2005 7:51 am

Duct Pressure For Engine Start

Sat Oct 29, 2005 9:57 pm

Hi,

Does any of you recall which was the minimum duct pressure where it was possible to start the engines? In this case, did you need almost the "standard?" 2 min starter ON for the spool process, I mean, was it a low spool rate?

Many Thanks
Tom
 
SlamClick
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RE: Duct Pressure For Engine Start

Sat Oct 29, 2005 10:50 pm

Well, an old MD-80 manual I still have says minimum of 36 PSI, minus 1 PSI for every thousand feet of airport elevation.

I have started DC-9 engines at Flagstaff Arizona and at Mexico City and don't recall them taking much more time to wind up than they did at lower elevations. Maybe some, but it really doesn't stand out in my memory.
Most pneumatic systems deliver plenty of pressure and volume.
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fr8mech
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RE: Duct Pressure For Engine Start

Sat Oct 29, 2005 11:05 pm

Different aircraft/engines have different pressures. The norm is somewhere around 35 psi with the valve open. Start times also differ with engine type and temperature.
When seconds count...the police are minutes away.
 
PhilSquares
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RE: Duct Pressure For Engine Start

Sat Oct 29, 2005 11:55 pm

Quoting Taguilo (Thread starter):
Does any of you recall which was the minimum duct pressure where it was possible to start the engines?

744 is 30 PSI. Start limit is 2 minutes from fuel on to stabilized at idle rpm.
Fly fast, live slow
 
320tech
Posts: 489
Joined: Mon May 17, 2004 11:38 am

RE: Duct Pressure For Engine Start

Sun Oct 30, 2005 12:14 am

A320 is minimum 28 psi, I believe, don't have the book handy. Max starter engagement is 2 minutes. Usually you see 30-35 psi from the APU, and 44 psi from the engine. Lots of pressure available.

If the starter's running for two minutes, there's a problem. I would say most starts are complete within 30 - 40 seconds.
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
 
taguilo
Posts: 73
Joined: Tue Aug 02, 2005 7:51 am

RE: Duct Pressure For Engine Start

Sun Oct 30, 2005 12:37 am

Thank you for the replies.

Now, minimum psi is measured BEFORE or AFTER switching starter to GND??
 
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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

RE: Duct Pressure For Engine Start

Sun Oct 30, 2005 2:14 am

B737 Min 30psi.Ideal 40psi.
regds
MEL
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B747FE
Posts: 217
Joined: Mon Jun 21, 2004 11:09 pm

RE: Duct Pressure For Engine Start

Sun Oct 30, 2005 3:36 am

Quoting Taguilo (Thread starter):
Does any of you recall which was the minimum duct pressure where it was possible to start the engines?

30 PSI (minus 1 PSI x 1,000 FT airport elevation) and time limit is 90 seconds to accelerate from "fuel on" to idle rpm, in the 747 Classic.

Quoting Taguilo (Reply 5):
Now, minimum psi is measured BEFORE or AFTER switching starter to GND??

Pressure must be checked after start valve is open.

Regards,
B747FE.
"Flying is more than a sport and more than a job; flying is pure passion and desire, which fill a lifetime"
 
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NZ1
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RE: Duct Pressure For Engine Start

Sun Oct 30, 2005 7:17 pm

767 is normally 34psi.

NZ1
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