744 Autostart

[BWBriscoe]

I will soon be starting my training on the 744, and I was flicking through the manual, and I had a query over the autostart system.

My question is, why would you want to start the engines without the autostart function? I recently purchased the ITVV video of the LHR-SFO flight, and the Captain on this flight used the manual start sequence (i.e. pull start switch, wait till 80% N2, then add fuel).

What situation would cause the other sequence to be used (fuel switch to run, then pull start switch)?

Cheers,

BWB

[A-FLOOR]

AFAIK the autostart is there to automatically and immediately relight a flamed-out engine inflight, no action from the crew would be required. The system handles the crossbleed, windmilling, fuel flow and ignition to get the engine running again.

[spannersatcx]

What situation would cause the other sequence to be used (fuel switch to run, then pull start switch)?

Autostart is a customer option and is not installed on every a/c.

Manual start would be starter on then fuel on, not the otherway round, or you'd be getting a lot of hot starts.

CX doesn't have it, the first BA ones didn't although this was retrofitted on them.

The system could be inop.

wait till 80% N2

That's a bit high (ok extremely high), depending on the engine could be anything from 10-25% N2 or N3.

[Carnage Matey!]

I will soon be starting my training on the 744,

Who with?

why would you want to start the engines without the autostart function

Inop autostart system or elevation above 6000 feet where autostart doesn't work so well.

What situation would cause the other sequence to be used (fuel switch to run, then pull start switch

Can't think of any situation where you'd want to do it in that order. Unles you want a really wet start.

[Harry G]

In our company we normally always use Autostart.

Two engines are started simultaneously. Eng 4 & 3, then 2 & 1. It's fairly quick and very straightforward, normally all 4 are up and running as the push is completed.

Between 2000' & 6000' (eg. J'burg) OR in ambient temps above 30C we still do an Autostart but only one at a time.

Above 6000' (eg. Mexico City) we use the Manual Start Procedure. (Autostart switch Off or "out"). The Autostart switch is then returned to the normal "on" posn after start ready for an in-flight autostart should it be needed.

These are RR motors.

Good luck, enjoy, it's a beautiful aircraft.

[BWBriscoe]

"That's a bit high (ok extremely high), depending on the engine could be anything from 10-25% N2 or N3"

Sorry, I did actually mean 20%! lol

So if autostart is installed and is operative, and we're below 6000', there is no other reason why a manual start should be used?

BWB

[Swedish Steve]

Just one point, before using Autostart make sure it is fitted!
Heard a tale about a chinese crew who picked up a B744 in CDG on a delivery flight. All their training had been on autostart equipped aircraft, but their company aircraft was not fitted with this option. Four engines overtemped and had to be changed.

[TotalBeginner]

BWBriscoe I also have the video that you refered to, and they definately use autostart. The capt pulls the start switch, but because the autostart switch is ON, the engine doesn't crank until the Fuel Control Lever is positioned to RUN.

If you watch the startup again, you'll see that imediately after pulling the start switch he moves the Fuel Control Switch to run, allowing the autostart system to sequence the engine start.

[gas path]

My question is, why would you want to start the engines without the autostart function?

Practice a manual start once in a while is not a bad thing.

What situation would cause the other sequence to be used (fuel switch to run, then pull start switch)?

Bad practice but it does work!