Writing inside the F-16 exhaust

I was looking up the tailpipes of the F-16s at the Miramar air show (no off color jokes, please ), when I noticed writing inside the exhaust of each jet . I thought the writing was pretty funny myself, especially "The Love Dock" on 85-404 .

I just have one question. How do they write something in this location without it burning off in flight?! Thanks in advance for any help you guys can give me!

That section of the engine only gets hot, it doesn't get the effects of the afterburner. Even so chalk that you see it written with will withstand about four or five flights before it starts to fade when written on the liner of the engine. If graphite is used it will cause the material to fail and a burn though will result. BTW I think your looking at a PW engine by the looks of the spray rings and arangement of the flame holder.

IDCrewDawg, please take this as a compliment - is there anything you don't know? Thanks for the answer to my question! I shudder to think about how the bit about the graphite was discovered . The pilots couldn't tell me how it was done, but I figured someone around here would know . Is "artwork" like this a normal part of the F-16 life?

Your answer made me think of another question, too. Just what is the inside of the end of the tailpipe where the afterburner is hottest made out of? My guesses would be either titanium or inconel. Am I close?

It's not titanum, I think steel with a ceramic coating in the hottest parts, but I am not positive about that. Take a look up the intake of an F-16 sometime, if its dirty there is usually alot of art work, not usually ment for anyone who could get offended. The best thing to use on the exhaust to mark it is brake dust and a bit of grease, it leaves a mark for about 3 days during normal two sortie per day flights. Paint marker works well on the inlet blades and struts. Chalk is the best though for hot abrasive surfaces.

The best thing to use on the exhaust to mark it is brake dust and a bit of grease, it leaves a mark for about 3 days during normal two sortie per day flights. Paint marker works well on the inlet blades and struts. Chalk is the best though for hot abrasive surfaces.

That sounds like the voice of experience ! I'll have to keep that in mind. If I ever get close enough to a MiG, I might just have to get some "art supplies" and put a big "AIM HERE" in the exhaust along with a big old bullseye !

I looked up the intake on 85-404 while they had the cover off. No artwork in there. I guess they didn't want to take a chance on offending any airshow spectators . I can't think of a better place to put artwork like that - after all, who's going to look up there anyway?

Air show jets are usually cleaned very throughly, so you most likely wouldn't see anything. That you saw something on one in the exhaust is actually unusual.

In that case, I'm glad I got to see it! It's always neat to get a glimpse behind the scenes of the F-16 community .

Art, can often be found inside panels. Weapons troops often will write in pylon doors. The exhaust in those pics is in fact an old crappy Pratt. He knows about graphite burning through because in times past it was not uncommon for folks to mark cracks in the can with a pencil to keep up with them. Burner cans tend to crack. The newer Pratts are not as bad as those. They appear to be from a 220/220E which should be the case when looking at the tail numbers.

I never realized how much artwork is applied to aircraft! I was concerned that the graphite induced burn throughs might have caused some problems at just the wrong moment. I can see why people thought that graphite would be good to use for marking cracks in the burner cans since it would show up well against the lighter color and it's pure carbon, so it won't burn. I'm thinking the graphite retained the heat from the burner flame and transferred it in a concentrated area, causing the burn-throughs. Is this how they happened?

I have photographed several F-16 'burner art' examples, all at public air shows.

Either burn throughs or hot spots that induce cracking. I also suspect the graphite may negate some of the properties of ceramic lining. The liner gets really dark over time so color is not the problem.

Those chalk marks stay on forever. On my plane it lasted for about the time of a motor phase, 100 hrs. I wish I had some pictures of ours, some very interesting phrases end up there, either from us or the eng troops.

Marks on turbine blades are made with “TEC certified black markers or silver pencils” which will last many hours of operation at high temperature. These marks are numbers to identify individual blades during inspections. Marks in the augmentor are made with silver pencils or chalk, which also lasts quite long for the area it is in. Fan blades are also numbered for identification. In addition to identification, fan blades are marked in areas of previous damage has been repaired or “blended.” If additional damage occurs in the same area as the previous repair, it is made obvious by the damage to the colored marking. Other engine "repair" marks are often made on tubing or cases as required.

“CAUTION - Marking pencils shall not leave residues of carbon, zinc, copper, lead, or similar contaminate which could damage parts when subjected to high temperature.”

It is TRUE that using a “common #2 pencil” will contaminate high temperature parts and cause premature failure. Jet engine technicians won’t even point at an engine with a regular pencil. There have been horror-stories of technicians writing names or identifying personal information on engines/parts with a pencil, only to have it permanently “burned” into the surface (for the mishap investigators) prior to the part/engine failing.

“….Only applicable Pratt & Whitney marking methods herein shall be used…..”

Temporary marking technical data is VERY specific citing specific vendors and vendor part numbers. Marks are made to specification as well. (Type, length, width, height, special symbols, etc.) There are many different colors authorized for each particular method. Engine marking colors include white, blue, yellow, red, black, orange, silver, and green.

Some examples:
Chalk (Dustless)
Crayon (Soft China Marker)
Dyes (Layout Dye) ‘DYKEM’
Marker (Bullet Felt Tip) ‘Sharpie Marker, Marks-A-Lot, Fast Mark’
Marker, Paint ‘SANFORD CORP’
Marker, Pen ‘Redi-Sharp’
Marker, Pen, TEC (Trace Element Certified) Sharpie Marker
Pencil (Hard/Colored Pencil) ‘SANFORD CORP’

For those authorized the specific data is available in (NAVY) NAVAIR 02-1-517 / (AIR FORCE) T.O. 2-1-111 “STANDARD MAINTENANCE PROCEDURES, NAVY AND USAF, P&W AIRCRAFT ENGINES” Section 10 “Marking of Parts”

It is funny to look at old air show photos and see just how many photos you have of people looking up the afterburner of fighters. I wondered why people would find that so interesting. Regardless, I did spot this one in Niagara fall a few years back. This is clearly a GE engine.

IDCrewDawg wrote:That section of the engine only gets hot, it doesn't get the effects of the afterburner.

The radiant heat from the burner makes this area VERY hot. Ever tried to remove that cone from an engine that has been running for a few years? Forget removing the nuts, and hope the bolts break when you try. Don't forget to keep the pieces out of the turbine or you'll be tearing it down as well. (Watch your knuckles too!) The heat would melt any other type of mark other than chalk, but what this area doesn't get is the blast from the exhaust that would simply blow the chalk away. As for using "other writing materials" in this area a word of caution: Carbon from breaks also heats up without burning away and could cause thermal damage to whatever it is on. See my post above.

See you at the engine shop Dawg........ (I said that with a smile.....)