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Question about the 737NG Engine start switch

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Question about the 737NG Engine start switch

Old 16th Oct 2012, 07:11
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Question Question about the 737NG Engine start switch

There is a question comes up in mind during a flight,
if I select the engine start switch as Ground instead of Continue, what will happen? will it broken the start motor or sth else?
And if we need to us e anti ice, is it ok use the FLT instead of the continue position?
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Old 16th Oct 2012, 09:01
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CONT = continuous use of the selected igniter ( left or Right)
FLT = continuous use of all igniters

The start switches are selected to prevent a flame out situation I believe so using FLT shouldn't be a problem.

Say you get yourself into severe turbulence you will put the start switches to FLT then you encounter icing so you put the TAI on.
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Old 16th Oct 2012, 09:10
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If I select the engine start switch as Ground instead of Continue, what will happen?
- it happened to me with an 'over-excited' Captain. Result?

Cry of 'NO!' from me
Cry of 'Oh S**T!' from him
Rapid return to CONT
Much tittering from RHS
Nothing else

Engineers told me the clutch would not engage
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Old 16th Oct 2012, 09:12
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he got excited for a long time,cause you need to PUSH before you TWIST

Reedited from pull to push...got bit excited myself

Last edited by de facto; 16th Oct 2012 at 12:40.
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Old 16th Oct 2012, 11:39
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B737900er, thank you, it helps!

btw, will the switches automatically come to OFF like you start the engine on the ground when N2 above 56% if you do that in the air?

Last edited by jjleo; 16th Oct 2012 at 11:43.
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Old 16th Oct 2012, 11:48
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Well, almost....in the NGs I use, one needs to PUSH the start selector switch IN to select GRND.

Last edited by EW73; 16th Oct 2012 at 11:49.
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Old 16th Oct 2012, 14:14
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The start switch solenoid will not energize therefore the start valve will not open and the clutch will not engage.
The DEU remove the electrical ground for the start switch solenoid as long as N2 is above 55 N2.
btw, will the switches automatically come to OFF like you start the engine on the ground when N2 above 56% if you do that in the air?
Yes

Last edited by de facto; 16th Oct 2012 at 14:16.
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Old 16th Oct 2012, 14:44
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Originally Posted by DF
he got excited for a long time,
- I'm not sure how to break this to you, but it takes most agile folk pretty much the same time both to Ground and Cont. If you find the action troubling, perhaps ask your co-pilot to do the start for you? Don't want you straining yourself. Wrist action can be vital.
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Old 17th Oct 2012, 07:44
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perhaps ask your co-pilot to do the start for you? Don't want you straining yourself
They always do..
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Old 17th Oct 2012, 08:26
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Quite right to. I used to have them carry my flight bag and do all the walk-rounds, especially if it was windy or raining.
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Old 17th Oct 2012, 10:11
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I make sure that if it rains they carry my flight bag around the aircraft and then [email protected]@@ at them why its wet
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Old 9th Aug 2019, 15:42
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Hey guys !

Reading this old topic, the following came to my mind:

- If I select CONT for the start switches and
- Select ignition on BOTH (not L or R).

Do we agree it would have the same effect as selecting FLT ?

In that case, why did they put a FLT position ? (as the same could be achieved with the CONT and BOTH combination).

There has to be a reason...

Thanks !
👍


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Old 9th Aug 2019, 17:38
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Originally Posted by greg765 View Post
Hey guys !

Reading this old topic, the following came to my mind:

- If I select CONT for the start switches and
- Select ignition on BOTH (not L or R).

Do we agree it would have the same effect as selecting FLT ?

In that case, why did they put a FLT position ? (as the same could be achieved with the CONT and BOTH combination).

There has to be a reason...

Thanks !
👍


Now you're thinking like a Frenchman
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Old 9th Aug 2019, 22:02
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Originally Posted by greg765 View Post
In that case, why did they put a FLT position ? (as the same could be achieved with the CONT and BOTH combination).

There has to be a reason..
Good old American KISS at its best.

FLT is more or less only used when both engines have failed or when this could occur soon (severe turbulence). By providing pilots with FLT position Boeing has simplified the memory items by using one step instead of two.
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