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Newbie Joined: Nov 08, 2006 Posts: 18 Status: Offline

It's getting cold again so now we have to watch for ice fod when the jets are starting or at EOR. just wondering what the deal with ice fod is all about?

Has ice actually foded out a engine, and what happens if ice forms on the intake when they are flying?

It just gets old standing and looking at the intake, which seems like for no reason. just want some information on this..

Thanks!

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Ice FOD is a very real thing. Have seen it many times. The outside temps and moisture levels have to be right for it to form. Once it begins to form, if you don't notify the pilot to shut down the engine, the ice FOD will build up and can come off the leading edges of the inlet in "chunks" and slam into the first stage of the engine blades. Bad News.....

I know it's cold outside this time of the year and a pain in the @*% to stand there and watch for it, but it sure beats having to pull that engine if it gets FODed out......

Ice can damage an engine just as badly as a bolt. I know it seems much softer but the damage can be just as severe. Check out the fuselage of an old C-130 right inline with the prop rotation.

Hi guys one question: what FOD means

It has something to do with safety - right ?

I know it's a stupid question Embarassed

It means Foreign Object Damage.

Newbie Joined: Nov 07, 2006 Posts: 18 Status: Offline

I know ice can damage an engine.. just about anythign can.. but can ice form on the intake when the jet is flying? If so what happens then?

It can, but there's a heated strut in the inlet that heats the engine inlet.

The purpose of the heated strut is prevent ice from forming on the strut, not to heat the engine inlet.

"but can ice form on the intake when the jet is flying? if so what happens then?"

Yes it can form in the intake while its flying, hence the reason for the inlet ice detector. The pilots can give you a better clue as to what they will do if they get inlet ice, my guess is an increase or a decrease in altitude. Or fly away from the conditions that are causing it.(and making sure the inlet ice switch is in the on position).

Ice is one of the hidden killers, all you will usually see is a lot of soft body impacts and some shattered ice impact panels.

I have seen it form on gas turbine and prop blades in flight. Attached is an NTSB Report on an engine ice incident on a Reno Air DC-9.

Salute!

OK, from the archives of ol' Gums "saves" of the Viper....

So we got slush at the EOR, maybe 30-35 degrees temp, and crew dawgs are looking and watching and ....

The heated strut works fine.

Take off and as I throttle back for the intermediate altitude my feet are knocked off the floor by a huge THUMP. I thot I had ingested a pelican or something. As I push throttle up I fel a slight vibration. So following Rule 1, I go back to where I was to begin with and retard throttle to maybe 85% rpm. Vibration lessens, but deep down inside I KNOW, ABSOLUTELY KNOW, that something is bad. Tell IP I'm chasing I gotta abort and I turn back for base.

I DO NOT MOVE the throttle again until on the runway. Speedbrakes, etc, keep speed under control.

So I get to the parking spot and shut down. Crew chief looks in the intake, then steps back hanging head down. This is bad, I'm thinking.

And it was!

How about 60+ blades bent, torn or missing? Right then I grew to love that P&W.

Seems clear ice had built up in the intake and broke loose shortly after takeoff.

If I had not had the "touch" to feel the slight vibration, I'll guarantee you all that the engine would have disintegrated during our scheduled ACM mission.

later,

501-tester wrote:

I know ice can damage an engine.. just about anythign can.. but can ice form on the intake when the jet is flying? If so what happens then?

Icing generally only occurs in a narrow range of conditions - too cold and it's snow - too warm and it's rain. The pilot can usually climb or descend a few thousand feet and stop the icing. Lindberg had to do that on his solo Atlantic crossing.

The 117 has a major problem with ice FOD. Has to do with those big ice trays it has for the intake. I was told that the alloy that they use for the motors in the 117 is a bit softer than most. Made this way so the blade will bend as as opposed to breaking. The first time I jumped an intake on one I about had a heart attack. gouges the size of nickles and quarters, Corners of blades missing. There is a windshield wiper deal right below the intake that squirts alcohol and knocks the big pieces off.

From the USAF F-16--OPERATIONS PROCEDURES manual volume 3 (11-2F-16):

3.3. Ground/Taxi Operations:

3.3.2. Ice/Snow Conditions. Do not taxi during ice and/or snow conditions until all portions of the taxi route and runway have been checked for safe conditions. When ice and/or snow are present on the taxiway, taxi on the centerline with a minimum of 300 feet spacing.

3.3.2.1. (USAFE) Units will specify minimum runway condition reading (RCR) for taxi operations. Units will establish local procedures to minimize inlet icing during ground operations.

3.3.3. Ice FOD Procedures. The following procedures apply when the conditions in T.O. 1F-16-1 indicate engine damage due to icing is possible.

3.3.3.1. If conditions warrant, the Supervisor of Flying (SOF)/Top 3 will have the first flight lead start 5 minutes early to check for inlet ice formation.

3.3.3.2. Position ANTI ICE switch to ON prior to engine start.

3.3.3.3. An ice FOD monitor must be available to monitor the engine inlet for ice buildup whenever the aircraft is stopped for an extended period of time (i.e. ramp/shelter and EOR). While taxiing, avoid unnecessary stops enroute to EOR. If possible, remain at ramp/shelter until traffic delays are eliminated. Avoid standing water and snow/slush accumulations. When pulling into the arming area, attempt to stop the aircraft over an area clear of water, ice, or snow.

3.3.3.4. Hold in the arming spot with an ice FOD monitor present until cleared for take-off.

3.3.3.5. Shutdown immediately if icing is visually detected and notify the SOF/Top 3. Make an appropriate entry in the aircraft forms. A qualified crew chief should accomplish an intake inspection prior to restarting the engine.

Anyone remember the "Ice FOD Dollies" they employed (at least at Hill) in the early 80s?

They were large, heavy sheets of metal on casters that one placed in front of the intake during ice FOD conditions. They were pulled out of the way by a large T handle prior to taxi.

I don't think they worked worth a damn. Much better was painting a black stripe on the lip of the intake so you could see the ice build up.

I remember one go where the ice formed so rapidly that six of the first ten lines had some sort of damage before we could get them all shut down.

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Ice FOD