F-16.net

I think so … It’s nice to have the JFS bottles built back up, prior to ignition, just incase you need JFS start energy.

Common sense applies here though … if you’re on Alert start them like normal and kick a$$ like normal

Viper, Viper Twisted Evil

F-16.net Sponsor

This message from our sponsor will disappear if you log on as a member.

I guess it all depends if you want the extra wear and tear on the JFS and JFS geartrain. Pro's and Con's either way really... Evil or Very Mad

Enthusiast Joined: May 17, 2007 Posts: 46 Status: Offline

Why? That's why you have the "T" handle. Very Happy

-70JG-00-1 says to transfer to idle anywhere from 20% (90 degrees F or higher) - 32% (max motor/cold weather). Generally if your JFS is up and running, and your motoring the engine, chances are it's going to start unless having engine problems. If your troubleshooting a known problem you should already have a mule on the way so you don't have to pump it up every 10 seconds.

Motoring the engine causes increased wear on your JFS, and clutch servo. Would you rather have to pump it up every now and then, or change a clutch servo?

The 1-minute "Motor to cool" was a procedure designed for the F100-PW-220. Confused

If the engine were "hot" after being recently run, the top half of the compressor rotor would be hotter than the bottom half. (Heat rises, cool sinks) When this occurred, the compressor would warp or what the engineers called "bowed rotor".

If you motored to cool, the temperatures inside the rotor would normalize, and the bowed rotor would straighten out.

Without motoring the bowed rotor, the compressor blade-tips would dig into the abradable material around the blades, and increase the clearances of the compressor. After a couple times starting hot like this, compressor stalls could occur due to the blade tips "leaking" air through the increased gap. Sad

I don't think (guessing here) GE motors require the 1-minute "motor to cool" nor do the F100-PW-229s. They have a high-compressor with a different design that is more rigid and does not "bow" like the -220's. Very Happy

-229s don't require a oil scavenge at shut-down either, and the bucket requirement to catch the fuel dump has been eliminated. The dump fuel is redirected back into the engine's fuel system.

I think 1 minute start are crap... They tear up the JFS and if we are going on with the 1 minute starts why must we always do start 2 even when the book says to do start 1 at a specific temp?

No need to create more work for and engine that does not require it.

Newbie Joined: May 03, 2005 Posts: 10 Status: Offline

cdhstang - Start 2 is preferred due to the increase toque available to the hydraulic start motor (2 bottles verses 1 bottle) and less drag from using the lube deprime valve. (I know it’s no fun pumping both bottles back up manually if the "Magic" doesn't work Smile

)

I really don't like P&W engines, let's keep the band-aid fix for "rotor warp" to the crappy F-16 motor.

IMHO I don't belive max motoring really hurts the JFS or associated components as much as it seems. On a prior deployment we used to max motor(up to 4 mins) for borescope insps which come up nightly or bi-nightly on deployments, especially if you have 25 hr borescope insps to deal with. But we never had any unusally start problems or issues. At least not more than normal.

I dont see any reason why you would have to its not reqd in the 70jg. As soon as i get the sec lite off i'm going over the horn. I dont waana take the chance of screwing up anything on the jfs. The last thing i wanna do is fry a clutch servo or fuel control. As for motoring for a scope it really doesent do too much good anyways. the new video scopes we have are so sensitive your gonna have to wait the 4 hours after flight anyways before its cool enough to use it.

a1378 wrote:

As soon as i get the sec lite off i'm going over the horn. I dont waana take the chance of screwing up anything on the jfs. The last thing i wanna do is fry a clutch servo or fuel control. As for motoring for a scope it really doesent do too much good anyways. the new video scopes we have are so sensitive your gonna have to wait the 4 hours after flight anyways before its cool enough to use it.

Hope you're not running -220s you'll kill them... I know it's been found some bases were having stall issues with -220s and they found out people there (pilots/maintenance) weren't following tech-data. Scratch a few more core modules! Evil or Very Mad

(Which makes it hard on the rest of us engine folks who have to wait months to get a core module in the first place!)

As for the starter, if it's running properly it won't hurt it to run up to it's limit. If you're frying clutch servos or fuel controls, something isn't right. T/S your JFS system. Rolling Eyes

Motoring an engine for maintenance cool-down is an excellent idea that works well depending on the outside air temperature. Air-conditioning unit hoses stuffed in the intake/exhaust with covers will cool it down quickly when deployed to HOT AORs. (And any maintenance folks sitting under the aircraft Wink

)

The new video-scopes are bad for 'hot' deployments just for that reason... They do not deal with heat well. Even at the ramp temperature, those scopes can fail and if you don't have a fiber-scope backup you're $crewed. Doh

That_Engine_Guy wrote:

Air-conditioning unit hoses stuffed in the intake/exhaust with covers will cool it down quickly when deployed to HOT AORs. (And any maintenance folks sitting under the aircraft Wink

Never gonna for get them times stuffing a A/C hose in the rear just to do a flameholder or trying to cool the core off quiclky to hurry up and get the scope in cause you know the turbine is probally fXXked from all the heat and sand!! Doh

Mush

Enthusiast Joined: Aug 24, 2007 Posts: 86 Status: Offline

Good points, about the "warping" issue, heard that from MANY a PW eng troop. Something else mentioned one inch above ^ engine dudes, settle that old debate- Ya gotta do exhaust work, (flamehoulder, whatever) where to shove the C-10 hose, front or back? You'd think back, but lotsa eng guys say, no, then you're just blowing everything the wrong way, screwing up the intake RAM, etc. Also, MAT insts used to say the whole pipe would actually cool quicker coming from the front, just give it a minute... Who be right? Or not? i dunno, ah just wave muh arms & pump gas (grunt) Shocked

Cooling the engine with an A/C will not warp or damage anything. A good cold day (below 0) back in the US would have the same effect on cooling the engine.

As for blowing air "the wrong way" I've seen windy days pushing more air through and engine backwards, than any A/C hose could ever dream.

Best method is using a hose at both ends, place intake/exhaust covers, then hang a hose under the engine panels with safety wire so that the air blows into and around the bottom side of the engine bay. Very Happy

Sucks working on any engine hot, but sometimes it just has to be done to meet the next sortie... Cool

F-16.net

Forum: F-16 Procedures

Should GE’s do the 1-minute motor?