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Single Engine Restart procedure using APU


bunraku

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Hi

 

 

What exactly is the process to restart an engine using the APU? I've seen some videos where people using the Motor Switch and some don't.

 

 

Is it as simple as

 

 

1) Bleed Air off

2) Start APU

3) APU gen on after decent time interval

4) Move throttle for affected engine over Indent?

 

 

Thanks

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See page 589 of the manual.

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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Ok, I need as much detail as possible in order to try to duplicate this. So

- Why is the engine off to begin? Left or Right engine?

- What missions is this happening?

- What versions are you using? (1.5.7.11476.394 or 2.1.1.11317.285.) please write the entire number of your version.

- What is your load out, speed, altitude?

- What time of the year? Time of the day?

- Atmospheric details: static or dynamic weather, temp, etc.

Any other information you can provide so anyone can try to duplicate.


Edited by mvsgas

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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Switching bleed air into off position isn't necessary if you try the APU restart (don't know if it is counterproductive by the way..)

Just follow the steps and it works.

- move throttle to OFF

- make sure you're below 20K ft and engine temp (of malfunctioning engine) is cooling down

- increase speed (dive) until you're below 15Kft

- move APU to START

- move working engine throttle to MAX

- set engine operate switch to MOTOR (of malfunctioning engine)

- move throttle to IDLE

- move engine operate switch to NORM

 

Works for me all the time...

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Thanks for replies guys. At work at the moment so doing this from memory. Not wanting to do a windmill start so just low level.

 

 

I am doing basic training campaign mission 2 in 1.5(Latest version just patched)

 

 

1) I am moving 1 engine to off.

2) Working engine to full and auto pilot on straight and level.

3) Bleed Air off

4) APU On

5) About 30 seconds later APU Gen on

6) Engine Operate Switch to Motor

7) Inoperative engine to Idle

 

 

Thanks

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Thanks for replies guys. At work at the moment so doing this from memory. Not wanting to do a windmill start so just low level.

 

 

I am doing basic training campaign mission 2 in 1.5(Latest version just patched)

 

 

1) I am moving 1 engine to off.

2) Working engine to full and auto pilot on straight and level.

3) Bleed Air off

4) APU On

5) About 30 seconds later APU Gen on

6) Engine Operate Switch to Motor

7) Inoperative engine to Idle

 

 

Thanks

It would be best if you try it in DCS and right after, come here and post while is fresh in your memory. I do not have that campaign so, again it would be best if you crate a simple mission, just place an A-10C in the air at 5000 feet, 50 percent fuel and no weapons. Can you restart left engine by following the manual then? Try the right engine. If not, come back and tell us the details.

 

I say this because I have no problem starting the aircraft as stated in the manual. Both engine start without issue.

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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The APU is designed to operate below 15k ft and engine APU restart should be performed below 10k ft.

Turn on the APU and APU generator --> engine operate switch to motor --> make sure itt is below 150°C then push throttle to idle --> engine operate switch to normal --> engine restarts itself.

[sIGPIC][/sIGPIC]

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I find difficulty with the supplied -1 or DCS procedure for single engine air start via APU.

 

The left engine is turned off by the lever in the off position and reduces eventually to 10.5% RPM and 50C ITT. The APU is stabilized at 100% RPM and normal EGT. Airspeed at 6,000' is 240-250 knots level. That's all normal.

 

However when the left engine operate switch is placed into motor the ENG START CYCLE caution illumiantes. Wtf? That shouldn't be. The cycle should only initiate when the lever is moved from off to near idle.

 

The RPM is 27% with right engine idle and 32% with right engine max as expected, the APU alone not providing the same quantity of bleed air energy as the combined effort.

 

If one does the same procedure omitting the motoring step the engine starts readily without the ENGINE START CYCLE caution illuminating while the lever is still in the off position. This happens even at 20,700'. Even without the APU a cross bleed engine start was accomplished with right engine max, level (180 IAS) at 20,700'!

 

Regardless of APU state, other engine idle or max, I get the engine cycle start with the affected engine lever off when I motor.

 

For those that have the procedure working properly, can you please test the following:

 

1. Left engine lever off

2. Left engine operate switch motor

3. Is ENGINE START CYCLE caution light on or off?

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Uhm, you’re incorrect about the “Engine Start Cycle” light, per the job guide when moving the ENG OPER switch to MOTOR the ENG START CYCLE light illuminates.

 

Or maybe I just don’t understand what you’re going on about.

 

I find difficulty with the supplied -1 or DCS procedure for single engine air start via APU.

 

The left engine is turned off by the lever in the off position and reduces eventually to 10.5% RPM and 50C ITT. The APU is stabilized at 100% RPM and normal EGT. Airspeed at 6,000' is 240-250 knots level. That's all normal.

 

However when the left engine operate switch is placed into motor the ENG START CYCLE caution illumiantes. Wtf? That shouldn't be. The cycle should only initiate when the lever is moved from off to near idle.

 

The RPM is 27% with right engine idle and 32% with right engine max as expected, the APU alone not providing the same quantity of bleed air energy as the combined effort.

 

If one does the same procedure omitting the motoring step the engine starts readily without the ENGINE START CYCLE caution illuminating while the lever is still in the off position. This happens even at 20,700'. Even without the APU a cross bleed engine start was accomplished with right engine max, level (180 IAS) at 20,700'!

 

Regardless of APU state, other engine idle or max, I get the engine cycle start with the affected engine lever off when I motor.

 

For those that have the procedure working properly, can you please test the following:

 

1. Left engine lever off

2. Left engine operate switch motor

3. Is ENGINE START CYCLE caution light on or off?

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What I'm going on about is the procedure to air start via APU if followed does not succeed.

 

OK, maybe cycle light should come on with lever off and engine motoring. But the problem is when you move the lever from off to idle the engine does not start!

 

But if you do not motor the engine you get a successful start when the lever is moved from off to idle. The procedure calls for motoring to get some core RPM before the attempt is made for a start (same for max bleed off good engine, high airspeed, etc.). But if you motor you spoil the attempt!


Edited by Frederf
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But if you motor you spoil the attempt!

No it does not. After you motor the engine, set the throttle to idle and move the engine operate switch back to normal ( as stated in the manual) and the engine will start.

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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On the track you left APU gen off and bleed air on. So I took control of the track, put left engine back to off, engine operate switch to normal, turn on APU gen and bleed air off, right throttle to max. Started to motor left engine, left throttle to idle and engine operate back to normal and engine started just fine.

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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Those actions may start the engine but I am referring to the procedure as written.

 

 

SINGLE-ENGINE RESTART.

1. Throttle (affected engine) - OFF.

NOTE


• If rapid cooldown is not observed within 5 seconds of shutdown, ensure that the affected throttle is positioned against the aft/OFF stop to shut off all fuel flow and permit engine cooling.

• If possible, descend below 20,000 feet MSL and increase airspeed to improve starting characteristics.

2. APU - START.

NOTE


APU starts can be made up to an altitude of 15,000 feet (most cases up to 20,000 feet).

3. APU generator switch - PWR.

4. Throttle (operating engine) - MAX.

5. Engine operate switch (affected engine) - MOTOR.

WARNING



















A 4% thrust loss will be experienced even with the APU running since above approximately 80% core RPM, engine bleed air is at a higher pressure than the APU can supply. This 4% thrust loss may be sufficient to preclude sustained level flight or seriously degrade single-engine climb performance in a critical thrust situation.




NOTE
• Starter is capable of motoring engine to approximately 24-28% core RPM.


• Placing the engine operate switch to MOTOR will provide rapid cooling of the engine. Cool engine until ITT below 150°C (100°C above 15,000 feet MSL).




6. Inoperative engine - Start.

7. Engine operate switch (affected engine) - NORM.

If restart was unsuccessful:

8. Throttle (affected engine) - OFF.

 

9. Crossfeed - As required.

 

10. Refer to SINGLE-ENGINE LANDING.

If restart is successful:

8. SAS switches - ENGAGE.

 

9. Crossfeed - As required.

 

10. Anti-skid - ENGAGE.

NOTE









There is a possibility for engine failure after successful engine restart.


 

 

 

Although it is not written explicitly. The wording may suggest that the engine should start completely (exceeding 56%) with the operate swtich in motor and then returned to norm. This has great similarity to the A-10A manual (ground, without automatic start) start process which does start with operate in motor and cautions against excessive time after engine start with operate in motor.

 

I did go back and try again APU GEN PWR to see if skipping that changed things.

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Those actions may start the engine but I am referring to the procedure as written.

Although it is not written explicitly. The wording may suggest that the engine should start completely (exceeding 56%) with the operate swtich in motor and then returned to norm. This has great similarity to the A-10A manual (ground, without automatic start) start process which does start with operate in motor and cautions against excessive time after engine start with operate in motor.

 

I did go back and try again APU GEN PWR to see if skipping that changed things.

Did you see page 589 on the DCS manual? It's the same thing I posted. You can argue all you want but I can get the engine re-started by the book all day long. You should work on it. I'm out

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To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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I'm referencing the -1 but the DCS manual is the same.

 

I am reporting that when I do the directed 7 steps I do not get an engine restart. There is no need to be upset about facts. We are either doing different steps getting different results or doing the same steps and getting different results.

 

(Affected) Off

APU Start

APU Gen Pwr

(Operating) Max

(Affected) Motor

(Affected) Start

(Affected) Norm

 

In each step I am allowing enough time for all relevant parameters to stabilize before continuing.

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As soon as you put the throttle to idle, turn engine operate back to normal, do not wait. AFAIK, putting the throttle to idle with engine motoring you are introducing fuel without ignition.

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To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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I'm referencing the -1 but the DCS manual is the same.

 

I am reporting that when I do the directed 7 steps I do not get an engine restart. There is no need to be upset about facts. We are either doing different steps getting different results or doing the same steps and getting different results.

 

(Affected) Off

APU Start

APU Gen Pwr

(Operating) Max

(Affected) Motor

(Affected) Start

(Affected) Norm

 

In each step I am allowing enough time for all relevant parameters to stabilize before continuing.

 

Obviously you're not, and you're not listening. As soon as you place the throttle over the hump set the switch from MOTOR to NORM and it'll start.

 

As soon as you put the throttle to idle, turn engine operate back to normal, do not wait. AFAIK, putting the throttle to idle with engine motoring you are introducing fuel without ignition.

 

You're correct.

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Indeed if the switch reposition from motor to norm is delayed by 2 seconds after the lever is positioned from off to idle the engine does not start. A start occurs if the switch reposition is made within a second.

 

That success or failure of the task is so time critical is not at all obvious from the written instruction. I humbly beg forgiveness for the audacity in investigating the matter.

 

Personally I will skip the motoring step entirely as there appears no situation which a start is successful from a motored RPM vice one which is unmotored.

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Thanks Snoop, always good to hear from you.

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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That success or failure of the task is so time critical is not at all obvious from the written instruction.

 

Very good point!

 

My in-flight restarts have had a certain hit or miss ratio that I couldn't really account for, but this might be the answer I didn't know the question to. :thumbup:

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Everything on engine starts is time critical. In real life is even worst, there is so many things we do not have to check or worry about in the sim. I never ran a RL A-10, obviously, but the first few times I ran an engine (F-16) I was 30 seconds behind the aircraft.

 

 

VOeXKWRxaMc

Try to check all of this while the video is playing, from the moment he turns the throttle to idle, light off should occur within 10 sec, you are looking for anticipated hot start (FTIT rapid rise through 750C on GE engine ), looking for hung starts, auto acceleration, engine fire, JFS off at 54% to 55%, stand by gen on by 58% to 60%, engine light out at 60%, main gen on within 5 to 10 seconds after standby gen. Oil pressure as soon as you reach idle and Hyd/oil pressure light should go out by 20 psid on the gauge but it should not go out prior to 15% RPM. And that is just the stuff I remember, I am sure there more I miss.

 

Maybe Snoopy can tell us more about what he had to check on RL A-10 engine start that we don't even think about within DCS.

To whom it may concern,

I am an idiot, unfortunately for the world, I have a internet connection and a fondness for beer....apologies for that.

Thank you for you patience.

 

 

Many people don't want the truth, they want constant reassurance that whatever misconception/fallacies they believe in are true..

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