Re: 777 Engine Startup

Date:         24 Oct 97 04:33:15 
From:         Matthew Willshee <96mjw@eng.cam.ac.uk>
Organization: University of Cambridge, England
References:   1
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On 16 Oct 1997, David Asher wrote:
> Does the Boeing 777 have a Autostart capability (a single switch that will
> perform all of the functions related to engine start)? I had read
> somewhere that one of the airlines involved with the design had requested
> this feature.

Yes.
This is the normal way of starting the engines.  Basically, you turn the
engine operation switch to start.  The airframe sends a message to the
Electronic Engine Control System (EECS) telling it to start.  EECS
controls all functions.

These are something like:
1) Starter Motor On (starter runs on compressed air)
2) Wait for shaft speeds to reach a preset level.
3) Fuel on, ignition on.
4) Check for evidence of start (there will be logic for dealing with
false starts).
5) Cut starter when engine is going fast enough to self-sustain.
6) Control to idle.
7) Send a message to the airframe to release the switch from the start
position.

I think you will find that autostart is fitted to most relatively new
aircraft/engine combinations.  I would suspect that airlines wouldn't
bother requesting it, as they would just expect it to be there.

--
Matthew Willshee                               E-Mail: mjw44@cam.ac.uk
Churchill College, Cambridge                         : 96mjw@eng.cam.ac.uk