Engine Restart in Flight

[Guest IAF747]

I know its not common, but I want to know the procedure for starting an engine in flight, should say restarting..... on the 777s.

[Chrjs]

Check the FCOM or FCTM. You will find them on the web easily. Everything is covered there.

 

Btw, the 777 has a digital checklist feature, so the plane will tell you on the screen what to do (well, besides the very few memory items).

[scandinavian13]

 

 

on the 777s.

 

In addition to what Chris said (everyone knows, after all, that I'm normally the one saying "read the manual" - I'd highly suggest taking a look at the QRH that will come with the 777 when it comes out):

 

On the 777, it's surprisingly easy:

The plane will display an in-flight start envelope to get the engine to restart.  This is because we're not using the APU to get the engine, so there is a range of speeds and max altitudes that are required for enough air to be pushed through the engine to get it restarted.  The AUTOSTART function (which is normally on) will continuously attempt to restart the engine.

 

Of course, verify this information yourself once you get your hands on the manuals.

 

You can also download the Engines and APU section from SmartCockpit.com.

[Guest IAF747]

In addition to what Chris said (everyone knows, after all, that I'm normally the one saying "read the manual" - I'd highly suggest taking a look at the QRH that will come with the 777 when it comes out):

 

On the 777, it's surprisingly easy:

The plane will display an in-flight start envelope to get the engine to restart.  This is because we're not using the APU to get the engine, so there is a range of speeds and max altitudes that are required for enough air to be pushed through the engine to get it restarted.  The AUTOSTART function (which is normally on) will continuously attempt to restart the engine.

 

Of course, verify this information yourself once you get your hands on the manuals.

 

You can also download the Engines and APU section from SmartCockpit.com.

Do you need to descend to 10000 feet to restart?

[scandinavian13]

 

 

Do you need to descend to 10000 feet to restart?

 

Haha - no.  10,000 feet is not some magical altitude in aviation, despite the sim attitude that it is.  I believe the altitude is variable, based on atmospheric conditions, but it's likely higher than FL220.  Otherwise, you'd just fire up the APU and start on bleed air at that altitude.

[Guest IAF747]

Haha - no.  10,000 feet is not some magical altitude in aviation, despite the sim attitude that it is.  I believe the altitude is variable, based on atmospheric conditions, but it's likely higher than FL220.  Otherwise, you'd just fire up the APU and start on bleed air at that altitude.

It might be the 757 I was thinking of that you needed to do that on.

[Chrjs]

I guess you think about the "emergency descent" altitude in case of a pressurization failure which is usually 10,000 ft or higher if there is higher terrain present. It should not have anything to do with engine inflight restart (better relight). Although flying with only one engine usually requires to descent (but more to an level of the mid 20's). There might be also some initial descent required if oyu want to do a windmill-restart (see a basic explanation here: http://en.wikipedia.org/wiki/Flameout)

[scandinavian13]

It might be the 757 I was thinking of that you needed to do that on.

 

Highly doubtful.  Forcing a crew to wait until that altitude to attempt a restart means you've killed 2/3rds-ish of your altitude just to try and get that all back.  That wouldn't make sense.

 

Again, there are no magical altitudes here: it's about the density of the air, and the speed of the fans to get the engine restarted.

[hopskip]

The 10,000ft altitude is about humans breathing. It's a conservative average altitude that humans should be able to breathe normally and be conscious at 10,000ft. Heavy unfit smokers and elderly people may even have trouble at 8,000ft, and fit athletic types may well be able to remain fully conscious and comfortable enough at FL180+. According to Wiki, the highest permanently settled village is in Peru, at 16,728ft altitude! And people live there for entire lifetimes. Obviously these people would find a decompression event even in the low FL200's quite bearable, even if their fellow passengers all start dropping unconscious around them.

 

Jet engines are not people and will not fall unconscious. They just need a certain volume of air running through them at the correct (high enough) velocity (airspeed) to spin the bits that need spinning fast enough.

 

On the ground the APU does this by sending bleed air down into the engine. In the air, your APU is likely to be off, and you have a readily available source of fast air available... your own airspeed.

 

at FL390 though, there's not much oxygen up there, and starting an engine requires a few things, a spark and burning fuel for one, and we all know that for something to burn, there needs to be heat, fuel and oxygen.

 

The jet engine itself is quite capable of running well up into the FL400's+ but the engine start requires a bit more effort as the big fan out front isn't spinning enough to push through enough air. The only way for that to happen is for the engine to be running. Before it is running, that fan needs some help to get running. Either APU air bleed, or by travelling fast through air of sufficient density.

 

And just like those athletes and Andes villagers, a Jet engine is quite capable of using the oxygen available well up into the FL200's to get started. Jet engines aren't overweight smoking unhealthy pensioners.

[EGLL77W]

From what I'm reading in my QRH about the LR/F - it doesn't mention a specific Altitude at all. 

 

There are differences in the start procedures if airspeed is at or below 270knts. Not sure if you really want me to recycle the entire QRH section here though...

[Airbusman330]

From what I'm reading in my QRH about the LR/F - it doesn't mention a specific Altitude at all.

 

There are differences in the start procedures if airspeed is at or below 270knts. Not sure if you really want me to recycle the entire QRH section here though...

Just give the cliff notes then.

[777simmer]

During a single engine failure, not severe damage, fire, etc but a failure without damage, the failed engine can be restarted if so desired/required.

 

Depending on your altitude, the remaining engine can or can not maintain current altitude.

 

If altitude can be maintained, nice :-)

open up the "Eng Fail" checklist which will guide you to securing that engine (fuel control switch cutoff) and thereafter restarting it (if desired/required).

 

if altitude can not be maintained (i.e cruising at FL380), then you will have to initiate a driftdown with the FMC (a very shallow Vnav descent with maximum continuous thrust on the remaining engine).

Then you can go into the "Eng Fail" checklist again.

 

If you have enough air going through the failed engine, then the checklist will guide you to perform a windmilling engine start. (typically at lower altitudes).

Just put the fuel control switch back to run and wait and see what happens.

 

If not enough air is going through the engine (i.e. during that driftdown from FL380), then the remaining engine can provide pneumatic pressure to turn the failed engine. This is called a crossbleed (Xbleed) engine start.

The EICAS system will display X-BLD, indicating that a cross bleed engine start is recommended.

The checklist will guide you through that as well.

(Start/ignition selector to start and fuel control switch to run, then wait and see).

(All valves in the pneumatic system will be set automatically as required for the Xbleed start)

 

So the APU is not normally used for an inflight engine start, as mentioned by others already

(but that does not mean it is not possible to do so. Just keep in mind that the APU might not be capable to provide sufficient air untill below about 22000ft! Xbleed can be used at any altitude)).

[Continental737]

I know its not common, but I want to know the procedure for starting an engine in flight, should say restarting..... on the 777s.

Here is the Non-normal procedure from my 777-200 Flight Manual. 

Edited July 24, 2013 by Chase
Removed manual pages

[PlainandSimplePaints]

http://m.youtube.com/watch?feature=m-ch-fea&v=vbxl3hc_pL8

Here's a video of what you would do in a engine failure they did not restart though

[johnsturm]

Erich Etter you may want to reread the forum rules reguarding posting of copyrighted material. Here is a quote of the relevant section:

 

"5) COPYRIGHTED MATERIAL IS NOT ALLOWED: Posting of copyrighted material such as flight manuals owned by Boeing or various airlines is not allowed in this forum. If you have questions related to copyrighted material, please contact a forum moderator for clarification."