What exactly would a hat do to a jet engine? Does it get burned to ashes or does it hit a fan and damage it?

Quote from: Littleguy on February 24, 2012, 02:18:00 AM
What exactly would a hat do to a jet engine? Does it get burned to ashes or does it hit a fan and damage it?

Damage and deform the fan blades.

It does not take a lot to ruin a high performance jet engine.

Having said that....the envionment on a civilan air port is a lot different then a military one.

F-16 with their low intakes are infamous for sucing up things...and the USAF spends a lot of time pushing the FOD mantra.

But at my air port in North Las Vegas we get a lot of buisness jets....and a lot of ramp workers wear hats and they are not nearly as anal about FOD as the military.

I think a lot of it is simply the military mind set.  There are some things we get into our heads that "this is critical" and you can't insert any common sense in the equation.

Force Protection and Safety are also areas where it is very hard to insert common sense once the FP or SE Gods have spoken.

More than likely, it would damage the compressor blades and possibly the gas-producer turbine blades. We typically never wore headgear on the ramp at Army air fields.

Man sucked into A-6 Intruder jet engine intake

Quote from: Eclipse on February 24, 2012, 12:38:16 AM

Quote from: lordmonar on February 24, 2012, 12:32:00 AM

Quote from: PHall on February 24, 2012, 12:29:45 AM

Quote from: Eclipse on February 23, 2012, 11:06:51 PM

Quote from: PHall on February 23, 2012, 10:59:04 PMNotice that the Cop is the ONLY person in that photo with a hat. Everyone else (i.e. the maintenance guys) is bare headed.

Incorrect.

Okay, other then the cop, who is wearing a hat? Because I sure don't see any hats besides that beret.

The guy with the back pack looks like he is wearing a black ball cap.

Yep.

Even looking at the picture under high magnification (400%) it looks like a bald spot to me.

Quote from: Littleguy on February 24, 2012, 02:18:00 AM
What exactly would a hat do to a jet engine? Does it get burned to ashes or does it hit a fan and damage it?

The turbine section at the rear of the engine is very hot and the blades are easily damaged.
Solid stuff like hats, especially hat devices or grade insignia, will knock the crap out of those blades.
With the potential of a uncontained turbine wheel failure being the worse case.
Turbine engines are expensive beasts to repair.

Quote from: PHall on February 24, 2012, 02:36:22 AM
Even looking at the picture under high magnification (400%) it looks like a bald spot to me.

A bald spot and a fairly misshapen head if that isn't a hat.

I have seen two fodded engines up close, and helped change one of them. I can say that the compressor blades take the brunt of the damage.

#1 was an A-6 that sucked the nose gear safety out of the BN's hans as he went in front of, instead of under, the intake in an attempt to install it. The fist-sized chunk of metal tore up the lower right quadrant of the stator blades, and the first two rows of compressor rotor blades. The flag made it all the way to, and through the hot section, and exited the exhaust a little bits pf charred red cloth. The J-52 is an olde style conventional jet engine. Helped change that one, and still have a compressor rotor blade somewhere in my collection of stuff.

#2 was a US-3A that sucked in an empty mail bag. (They didn't nickname them Hoovers for nothing.) The fan took the major hit, and the pilot shut it down soon enough that it saved the hot section. The TF-34 is a high-bypass, turbofan style jet engine.

Quote from: Eclipse on February 24, 2012, 02:33:03 AM
Man sucked into A-6 Intruder jet engine intake

I saw that on the Discovery Channel or some similar program. It's just incredible to me that he was able to survive that incident. I wouldn't be surprised if he changed his job after that one!

He survived because the first thing you hit in a J-52 is stationary parts. His head and shoulder were up against the inlet guide vanes, and the pilot shut it down quickly. His arms and hands were behind him.

Had he been sucked into a turbo-fan, he would not have survived.

I'm not sure what he did after his recovery.

First, he likely changed his shorts.

Quote from: SarDragon on February 24, 2012, 03:23:54 AM#2 was a US-3A that sucked in an empty mail bag. (They didn't nickname them Hoovers for nothing.) The fan took the major hit, and the pilot shut it down soon enough that it saved the hot section. The TF-34 is a high-bypass, turbofan style jet engine.

High bypass turbofans are much more damage tolerant.
Usually if the bird or whatever just goes through the fan section the damage is minimal. Usually a good visual inspection and blending the nicks in the fan blades will do the job.
Now if it goes through the core section (the hot section) then the engine is toast. At a minimum you gotta bore scope it and will probably require a teardown.
They usually just replace the engine so the airplane will be back in service quicker and so they can do the teardown in the shop.
If the FOD makes it to the turbine wheels, it gets expensive real fast!

That canvas sack really trashed the fan and stator vanes. Not just nicks, but bends. Some of the blades were bent enough to contact the outer casing.

Quote from: FlyTiger77 on February 24, 2012, 02:25:40 AM
We typically never wore headgear on the ramp at Army air fields.

Army Aviation is primarily helicopter and light prop/turboprop fixed-wing though, isn't it?  Wouldn't that mean a little bit less chance of FOD ingestion by an engine (not ZERO chance, LESS chance)?

My brother-in-law works for GE...I forget what he said just one of those compressor vanes costs, but it's big $$$.

I remember airshows with (mostly ANG) A-7's...there was a bird with a low-slung big mouth.



The Navy versions also probably didn't do wonders for carrier-deck safety...

Quote from: CyBorg on February 24, 2012, 06:05:01 AM

Quote from: FlyTiger77 on February 24, 2012, 02:25:40 AM
We typically never wore headgear on the ramp at Army air fields.

Army Aviation is primarily helicopter and light prop/turboprop fixed-wing though, isn't it?  Wouldn't that mean a little bit less chance of FOD ingestion by an engine (not ZERO chance, LESS chance)?

Agreed, but the major hazard is spinning airfoils, and folks chasing errant hats. It's a really hard thing not to want to do.

QuoteMy brother-in-law works for GE...I forget what he said just one of those compressor vanes costs, but it's big $$$.

The price of a new TF34-GE-400 is $1,953,400.

QuoteI remember airshows with (mostly ANG) A-7's...there was a bird with a low-slung big mouth.

The Navy versions also probably didn't do wonders for carrier-deck safety...

Due to the layout of the airframe, they were much harder to get complacent about. All of the stuff that needs attention while the engine is running is well away from the intake. The A-6s and F-4s had a higher incidence of sucking people in. A-7s, F-8s, and S-3s had bigger issues with just sucking trash off the ramps and flight deck.

Quote from: SarDragon on February 24, 2012, 07:01:39 AM

Quote from: CyBorg on February 24, 2012, 06:05:01 AM

Quote from: FlyTiger77 on February 24, 2012, 02:25:40 AM
We typically never wore headgear on the ramp at Army air fields.

Army Aviation is primarily helicopter and light prop/turboprop fixed-wing though, isn't it?  Wouldn't that mean a little bit less chance of FOD ingestion by an engine (not ZERO chance, LESS chance)?

Agreed, but the major hazard is spinning airfoils, and folks chasing errant hats. It's a really hard thing not to want to do.

With tail rotors spinning much faster and around a horizontal axis presenting a much greater danger.

Quote from: CyBorg on February 24, 2012, 06:05:01 AMArmy Aviation is primarily helicopter and light prop/turboprop fixed-wing though, isn't it?  Wouldn't that mean a little bit less chance of FOD ingestion by an engine (not ZERO chance, LESS chance)?

Less FOD ingestion, true, but not less potential for damage. Even a mild nick on a rotor blade has to be inspected, and I've seen blades replaced for things I didn't even realize would be a problem.

I haven't been around Army Aviation much, so I plead ignorance.

Yes, obviously there are FOD hazards there too.

I would say that CAP personnel wearing a hat there should be up to the senior Army commissioned/warrant officer or SNCO on scene.

Like what has been said about four times already, he who owns the airfield makes the rules on hat wear.
When in doubt, ask!

It is a national regulation. Covers are not to be worn on the flight line do to risk that they will be blown on to the airstrip and or be sucked into an engine of a jet.