Never stop engines from MAX power :)

[StrongHarm]

After 5 minutes at IDLE, set left throttle to OFF and confirm core RPM reaches 5% and ITT is below 200c

 

I like to motor the engines for 60seconds before shutdown. Paulrkiii can probably provide the RL procedure (motor while watching temp or time and how much). 60 seconds seems to work for me. Here's a pic of the ITT temps after motoring the left engine, but immediate shutdown of the right.

 

 

As per checklist the ITT gauge must be below 150c before restarting. As you can see, the left engine is at temp for restart after motoring it for 60sec. The right engine is at 400c. It took 12 minutes for the right engine to cool down to 150c since I didn't motor it.

 

Here's my shutdown procedure for quick turn around:

*Shut off pitot heat after landing

*Request ground power (since there's currently a bug when switching from APU to Engine Gen that causes a break in power to some systems)

*Start APU (don't need APU gen as you have ground power)

*Left Engine Operate Switch to Motor

*Left engine shutdown (ALT+END)

*Motor for 60sec - start refuel

*Left Engine Operate Switch to normal

*Right Engine Operate Switch to Motor

*Right engine shutdown (CTRL+END)

*Motor for 60sec - start rearm

*Right Engine Operate Switch to normal

*Shut down APU

*Wait 3min for repairs to take place

 

All systems will still be on line since you have ground power on, so alignment etc won't be necessary. After engine startup you should reload DSMS to reinitialize weapons. Don't forget to turn pitot heat and other systems from your post landing checklist back on before takeoff.

 

Take note that I use the reverse procedure for startup. I motor the engine to 30% rpm before putting the Engine Operate Switch to normal to start fuel flow and light the fires.

[MrYenko]

...but they differ greatly from engine to engine and jet to jet, based on the engine tuning. "

 

...And whether the hot sections look like someone took bites out of the turbine buckets. :megalol:

[MrYenko]

I like to motor the engines for 60seconds before shutdown. Paulrkiii can probably provide the RL procedure (motor while watching temp or time and how much).

 

*snip*

 

Take note that I use the reverse procedure for startup. I motor the engine to 30% rpm before putting the Engine Operate Switch to normal to start fuel flow and light the fires.

 

Using the air starter to rotate the engine is verboten in most engines I've dealt with, unless the core is at 0% RPM. The starter clutches don't like clash engagements very much.

 

Motoring the engine to a higher RPM on start isn't such a big deal, but it doesn't accomplish much on the A-10, due to the fully automated start. If the computer/fuel control doesn't see the proper RPM, temperature, and pressure in the combustion section, it's not going to squirt fuel. Simple as that.

 

On CF6-50s, flight manual procedure is fuel on at 10% N1 RPM, IIRC, whereas for maintenance, we'd motor to 15 or even 20% before fuel on. Less chance of fuel out the tailpipe, followed by a rather impressive light show. ;)

[Snoopy]

I like to motor the engines for 60seconds before shutdown. Paulrkiii can probably provide the RL procedure (motor while watching temp or time and how much). 60 seconds seems to work for me. Here's a pic of the ITT temps after motoring the left engine, but immediate shutdown of the right.

 

 

As per checklist the ITT gauge must be below 150c before restarting. As you can see, the left engine is at temp for restart after motoring it for 60sec. The right engine is at 400c. It took 12 minutes for the right engine to cool down to 150c since I didn't motor it.

 

Here's my shutdown procedure for quick turn around:

*Shut off pitot heat after landing

*Request ground power (since there's currently a bug when switching from APU to Engine Gen that causes a break in power to some systems)

*Start APU (don't need APU gen as you have ground power)

*Left Engine Operate Switch to Motor

*Left engine shutdown (ALT+END)

*Motor for 60sec - start refuel

*Left Engine Operate Switch to normal

*Right Engine Operate Switch to Motor

*Right engine shutdown (CTRL+END)

*Motor for 60sec - start rearm

*Right Engine Operate Switch to normal

*Shut down APU

*Wait 3min for repairs to take place

 

All systems will still be on line since you have ground power on, so alignment etc won't be necessary. After engine startup you should reload DSMS to reinitialize weapons. Don't forget to turn pitot heat and other systems from your post landing checklist back on before takeoff.

 

Take note that I use the reverse procedure for startup. I motor the engine to 30% rpm before putting the Engine Operate Switch to normal to start fuel flow and light the fires.

 

By the time the jets get back to the spot to shutdown and we've done our recovery requirements the engines are ready to shut down. No motoring just #1 off, wait for fuel drain then the same with #2.

 

 

Motoring the engine to a higher RPM on start isn't such a big deal, but it doesn't accomplish much on the A-10, due to the fully automated start. If the computer/fuel control doesn't see the proper RPM, temperature, and pressure in the combustion section, it's not going to squirt fuel. Simple as that.

 

)

 

Somewhat true, and in the 90s most pilots didn't motor first but every pilot I've launched in the last year always motors the engine before taking the throttle over the hump...I've seen a few A-10s not start correctly and fuel was steady pumping...

[MrYenko]

Somewhat true, and in the 90s most pilots didn't motor first but every pilot I've launched in the last year always motors the engine before taking the throttle over the hump...I've seen a few A-10s not start correctly and fuel was steady pumping...

 

Good to know. I figured the autostart would be a bit... Smarter... Than that. See what happens when I think?

[Temphage]

Not unique to the A-10. On -15s, the engines are motored for about fifteen seconds before being pushed over the hump. As well the same, on shutdown, you just shut them off. Never heard of motoring an engine prior to shutdown, even with P&W-229s which run quite a bit hotter than -220 engines. on the plus side, -229s don't piss fuel all over themselves... undoubtedly the engine's cooled itself adequately enough by the the time the aircraft taxi to EOR, dearm, taxi to the ramp, and then get pinned up.

Edited March 26, 2011 by Temphage

[EtherealN]

"Flying at max power is not uncommon, but most guys I flew with flew at something under max power so the wingman had some room to keep up. You never plan to fly at max because there is no way to catch up if you get behind.

 

Standard procedure for multi-ship operation - you'll often do this even with formation takeoff. Going back to 97% as opposed to MIL might seem like a small thing, but it can really make your wingman's life a lot easier and allow him to stay in rather than having to do an actual rejoin if he botched the timing on release.

[StrongHarm]

I motor them as part of the shutdown routine to cool them down so I can get in the air quicker on a turn around. It's the difference between 60sec of motor or 12min of cool down (see above pic). IRL does the engine cool down a lot quicker? I've had engine failures from restarting the engines above 150c.

[Rainmaker]

Not unique to the A-10. On -15s, the engines are motored for about fifteen seconds before being pushed over the hump. As well the same, on shutdown, you just shut them off. Never heard of motoring an engine prior to shutdown, even with P&W-229s which run quite a bit hotter than -220 engines. on the plus side, -229s don't piss fuel all over themselves... undoubtedly the engine's cooled itself adequately enough by the the time the aircraft taxi to EOR, dearm, taxi to the ramp, and then get pinned up.

 

 

-220's aren't motored, but they are scavenged. The 220's do not have a recirculation circuit in them, hense the reason we have to use fuel tubes to catch the overboard gas. The motors are scavenged to lube the engine bearings prior to shutdown. You'll hear a throttle up for 5-10 seconds to about 75%, then back to idle to allow engine to stabilize before going to idle cutoff.

[Snoopy]

I motor them as part of the shutdown routine to cool them down so I can get in the air quicker on a turn around. It's the difference between 60sec of motor or 12min of cool down (see above pic). IRL does the engine cool down a lot quicker? I've had engine failures from restarting the engines above 150c.

 

I motor them before restart for 2 reason....first is to purge residual fuel (although I doubt it's modeled in the sim) and second is to get the temp to proper levels.

[Temphage]

-220's aren't motored, but they are scavenged. The 220's do not have a recirculation circuit in them, hense the reason we have to use fuel tubes to catch the overboard gas. The motors are scavenged to lube the engine bearings prior to shutdown. You'll hear a throttle up for 5-10 seconds to about 75%, then back to idle to allow engine to stabilize before going to idle cutoff.

Yeah, forgot to mention that. Not 'motoring', but I assumed it was just to burn off excess fuel to limit the deluge that pours out the bottom.

 

God what a piece of crap engine.

[MrYenko]

Yeah, forgot to mention that. Not 'motoring', but I assumed it was just to burn off excess fuel to limit the deluge that pours out the bottom.

 

God what a piece of crap engine.

 

Civvie engines have a pressurization and dump valve that dumps the residual fuel pressure into what is essentially a catch-can, that is then recycled into the fuel system the next time the engine runs. If the P&D valve goes bad, you'll get a stream of fuel out the drain mast at every shutdown.

 

I know some military engines don't have this feature, but every civilian engine I've worked on does.

[Snoopy]

Civvie engines have a pressurization and dump valve that dumps the residual fuel pressure into what is essentially a catch-can, that is then recycled into the fuel system the next time the engine runs. If the P&D valve goes bad, you'll get a stream of fuel out the drain mast at every shutdown.

 

I know some military engines don't have this feature, but every civilian engine I've worked on does.

 

A-10 has a catch can.....but we have to connect it to the drain tube....

[StrongHarm]

I motor them before restart for 2 reason....first is to purge residual fuel (although I doubt it's modeled in the sim) and second is to get the temp to proper levels.

 

That makes sense Paul. I've been motoring on start as well, but only until it hits 30% rpm. I'll be changing my procedure to cooldown motor on restart rather than on shutdown. I just wonder if the engine damage I've experienced was from shutting down hot, or starting hot. I'll do some testing.

[MrYenko]

A-10 has a catch can.....but we have to connect it to the drain tube....

 

:laugh:

[robmlufc]

A-10 has a catch can.....but we have to connect it to the drain tube....

 

Harrier is similar you need to manually drain it, screwdriver and rags around your arm.

[Snoopy]

Harrier is similar you need to manually drain it, screwdriver and rags around your arm.

 

15 years ago with just let it dump onto the ramp then in 1996 we had to start catching the fuel, EPA and all that fun stuff.

[hassata]

What is motoring exactly? Running the engine with only the fuel flow remaining in the engine, or some such thing?

[fragged]

What is motoring exactly? Running the engine with only the fuel flow remaining in the engine, or some such thing?

 

Running the motor with ram air from the APU or some other source with no fuel.

 

Or I could be totally wrong.

[sobek]

I motor them before restart for 2 reason....first is to purge residual fuel (although I doubt it's modeled in the sim) and second is to get the temp to proper levels.

 

I have actually had failure to light off when not motoring on a restart. After the engine is purged, it lights off just fine. I remember that residual fuel buildup in some cases was modelled in BS too.

Edited March 26, 2011 by sobek

[sobek]

Running the motor with ram air from the APU or some other source with no fuel.

 

Or I could be totally wrong.

 

Nope, that's about right.

[Rainmaker]

What is motoring exactly? Running the engine with only the fuel flow remaining in the engine, or some such thing?

 

Sort of...

 

You are basically spinning the motors, in this case using the apu, without opening the main fuel shutoff or running the ignitor plugs in the engine. You can do this to accomplish such things as windmilling the turbine blades to cool the engine's core temp or to purch excess fuel away to prevent what's known as a hot start.

[airdog]

Most newer jet engines did away with the p&d valve they now squirt the last bit of fuel into the engine when shut off is selected......if you listen carefully on newer aircraft you will hear the engine surge a bit on shutdown

[Yo-Yo]

I motor them before restart for 2 reason....first is to purge residual fuel (although I doubt it's modeled in the sim) and second is to get the temp to proper levels.

 

No doubts - it's modelled. :)

[Snoopy]

No doubts - it's modelled. :)

 

Good to know!!

 

Now, if we don't and you try to start can we get the flame that shoots out of the tailcone like realworld when I pilot forgets :D