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How Does Dirt Form On Aircraft?  
User currently offlinerjm777ual From UK - England, joined Nov 2011, 246 posts, RR: 0
Posted (2 years 1 month 5 days 3 hours ago) and read 6501 times:

How exactly does dirt form on aircraft? My first thought was pollution, but that didn't seem right. Any ideas?


Greetings from Dulles!
24 replies: All unread, jump to last
 
User currently offlinebrilondon From Canada, joined Aug 2005, 4116 posts, RR: 1
Reply 1, posted (2 years 1 month 5 days 3 hours ago) and read 6473 times:

Dust, air pollution, grime from what ever is on the ground. How does dirt get under my fingernails when I don't leave my office all day?


Rush for ever; Yankees all the way!!
User currently offlineSeptember11 From United States of America, joined May 2004, 3623 posts, RR: 21
Reply 2, posted (2 years 1 month 5 days 2 hours ago) and read 6355 times:

Shoes? Dirt from underneath shoes are brought into planes.


Airliners.net of the Future
User currently offlinefr8mech From United States of America, joined Sep 2005, 5330 posts, RR: 14
Reply 3, posted (2 years 1 month 4 days 10 hours ago) and read 5549 times:

How does dirt get on cars. Same mechanism. Don't discount pollution.


When seconds count...the police are minutes away. Never leave your cave without your club.
User currently offlineALTF4 From United States of America, joined Jul 2010, 1206 posts, RR: 4
Reply 4, posted (2 years 1 month 4 days 10 hours ago) and read 5545 times:

I throw mud at Air France planes. Apparently I'm fairly effective - people on here complain about AF planes being so dirty!

In all seriousness, think about the smoke/exhaust you see trailing out of an engine on climb-out, especially if you're looking at a plane from the ground. Certainly enough of that is left in the air, at least on the runway, for the plane taking off behind to catch some of it.



The above post is my opinion. Don't like it? Don't read it.
User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 5, posted (2 years 1 month 3 days 6 hours ago) and read 5102 times:

Quoting ALTF4 (Reply 4):
I throw mud at Air France planes


Excellent!...Thrust reversing creates soot around the wing roots and whole area...Overtime, rivets and fasteners loosen and galling creates small dirty trails of dark grey aluminum. Think its called "fretting". Corrosion on bare metal and topcoat paint oxidation all add the make the airframe look like crap. Oxidized paint holds dirt , bird poo and all other stains forever.
Don't ever under estimate pigeon craps strength!. On a flight from NY to Germany, a New York pigeon pooed on the wing. That poo last the entire flight into Europe the next a.m.!


User currently onlineStarlionblue From Greenland, joined Feb 2004, 16991 posts, RR: 67
Reply 6, posted (2 years 1 month 3 days ago) and read 5035 times:

Quoting soon7x7 (Reply 5):
Don't ever under estimate pigeon craps strength!. On a flight from NY to Germany, a New York pigeon pooed on the wing. That poo last the entire flight into Europe the next a.m.!

Yeah that stuff is sticky! Also perhaps it was in a slight flow depression area. 



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently onlinefrancoflier From France, joined Oct 2001, 3735 posts, RR: 11
Reply 7, posted (2 years 1 month 2 days 23 hours ago) and read 5012 times:

Quoting ALTF4 (Reply 4):
I throw mud at Air France planes. Apparently I'm fairly effective - people on here complain about AF planes being so dirty!

B*tch, please.
Don't flatter yourself.
If anything, the water content of the mud cleans the crap that's underneath.



Looks like I picked the wrong week to quit posting...
User currently offlinehorstroad From Germany, joined Apr 2010, 243 posts, RR: 0
Reply 8, posted (2 years 1 month 2 days 17 hours ago) and read 4945 times:

grease, rubber, carbon dust, hydraulic fluid, oil, coffee, dust and dirt from the ground/atmosphere

User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 9, posted (2 years 1 month 11 hours ago) and read 4612 times:

Dust in the Atmosphere... adherence increases if there is an oil/fluid leak.


Think of the brighter side!
User currently offlineNorthwest727 From United States of America, joined Jul 2005, 491 posts, RR: 1
Reply 10, posted (2 years 4 weeks 1 day 18 hours ago) and read 4456 times:

Another thing is soot and oil blowing out of the exhaust of turbine engines. Ever notice on Pratt and Whitney Canada PT6A powered airplanes, there is a trail of soot and oil behind the exhaust stacks? I've seen what those engines do to a freshly polished/waxed Piper Meridian after just an hour's flight, so after several hours, you can imagine what the airplane looks like.

You can also see the stains on 727s, old 737-100/200s on the fuselage, DC-9s, Tupolev 154s, etc right around the vicinity on the thrust reversers.


User currently offlineTod From Denmark, joined Aug 2004, 1724 posts, RR: 3
Reply 11, posted (2 years 4 weeks 1 day 17 hours ago) and read 4442 times:

The stuff coming out of the drain masts can add pretty streaks too.

User currently offlineL-188 From United States of America, joined Jul 1999, 29791 posts, RR: 58
Reply 12, posted (2 years 4 weeks 1 day 6 hours ago) and read 4227 times:

My last airline had a white Metro III that at one point had been flown by Horizon Air.

Every summer it would get all these little red splats all over the nose from all the bugs and Mosquitos that it would hit inflight (this being Alaska, many blood sucking Mosquitos). Anyway that earned it a nickname amount the mechanics.

Since this is a family forum I will not repeat the nickname here, but it was called a feminine hygiene product,



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offlineL-188 From United States of America, joined Jul 1999, 29791 posts, RR: 58
Reply 13, posted (2 years 4 weeks 23 hours ago) and read 4149 times:

Another source of filth on aircraft you don't see nearly as much these days but get some photos of DC-10's taken back in the 1970's through the middle 1980's and you will often, especially on white painted aircraft see a long brown streak starting from the cabin outflow valve.

That is a nicotine stain. Basic back when you still had smoking on aircraft when the planes would land, the outflow valve would open and all the smoke filled air from inside the aircraft would exit through that valve and cause that stain down side of the airplane.

There used to be a really good photo of a Western DC-10 on this site with that streak in full evidence, but I haven't able to locate it.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offline737tdi From United States of America, joined Sep 2007, 785 posts, RR: 1
Reply 14, posted (2 years 4 weeks 22 hours ago) and read 4135 times:
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Quoting L-188 (Reply 13):
the outflow valve would open and all the smoke filled air from inside the aircraft would exit through that valve and cause that stain down side of the airplane.





Even with the outflow valve closed there is a tremendous amount of air leaving the aircraft, through the outflow valve, the galley and lav. vents etc. This is what caused the streaks, not when the outflow valve opened on landing, it partially opens and closes thousands of times during the flight. The amount of airflow into the cabin is pretty much constant, cabin pressure is maintained/controlled through the outflow valve modulating.

Keep in mind also that there are fluid leakage limits, whether it be 1 drop per minute etc.. It will create an environment for dirt to stick too.

Then you have air pollution as mentioned earlier. Walk outside at night and shine a flashlight vertically in front of your eyes. You will see tons of debris in the air, most being plant origin but it still makes an aircraft very dirty.


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 15, posted (2 years 4 weeks 20 hours ago) and read 4114 times:

Thats why routine washing followed by a polish does help visually and aerodynamically.


Think of the brighter side!
User currently offlineNorthwest727 From United States of America, joined Jul 2005, 491 posts, RR: 1
Reply 16, posted (2 years 4 weeks 14 hours ago) and read 4038 times:

Quoting L-188 (Reply 13):
That is a nicotine stain.

Very true; I think one of the "clues" investigators found behind the cause of JAL123 was nicotine stains around the failed doubler plate on the rear pressure bulkhead...stains left by cigarette smoke-laden air escaping passing by the failing seal.


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 17, posted (2 years 3 weeks 6 days 21 hours ago) and read 3847 times:

In those days of Nicotine fumes.....The clogging of the relief valve filters was a problem that occured a lot.


Think of the brighter side!
User currently offline737tdi From United States of America, joined Sep 2007, 785 posts, RR: 1
Reply 18, posted (2 years 3 weeks 6 days 6 hours ago) and read 3742 times:
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Hawk21: I see you remember those days, remember changing the outflow valves then? Wow they were a sticky mess plus anything behind the aft bulkhead in the aft. bag bin was coated in gunk.

User currently offlinecomorin From United States of America, joined May 2005, 4895 posts, RR: 16
Reply 19, posted (2 years 3 weeks 5 days 19 hours ago) and read 3668 times:

Would flying a plane through rain at 500 mph wash off all the dirt? Or does boundary layer effect get in the way?

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 20, posted (2 years 3 weeks 5 days 19 hours ago) and read 3651 times:

Quoting comorin (Reply 19):
Would flying a plane through rain at 500 mph wash off all the dirt? Or does boundary layer effect get in the way?

That will help only at the leading edges; boundary layer kills most of that off for most of the rest of the plane, especially towards the backs of things.

Tom.


User currently offlinecomorin From United States of America, joined May 2005, 4895 posts, RR: 16
Reply 21, posted (2 years 3 weeks 5 days 14 hours ago) and read 3579 times:

Quoting tdscanuck (Reply 20):
Quoting comorin (Reply 19):
Would flying a plane through rain at 500 mph wash off all the dirt? Or does boundary layer effect get in the way?

That will help only at the leading edges; boundary layer kills most of that off for most of the rest of the plane, especially towards t

Thank you for confirming that; somewhat like what happens when a car is driven through the rain.


User currently offline817Dreamliiner From Montserrat, joined Jul 2008, 2182 posts, RR: 1
Reply 22, posted (2 years 3 weeks 5 days 4 hours ago) and read 3480 times:

Quoting comorin (Reply 19):

Would flying a plane through rain at 500 mph wash off all the dirt? Or does boundary layer effect get in the way?

Not really. What you need to remember is that an aircraft fuselage is not a perfectly smooth surface and there will be areas where dirt will form regardless of the air friction as its flying.



Reality be Rent. Synapse, break! Vanishment, This World!
User currently offlinerfields5421 From United States of America, joined Jul 2007, 7571 posts, RR: 32
Reply 23, posted (2 years 3 weeks 5 days 2 hours ago) and read 3458 times:

Quoting rjm777ual (Thread starter):
How exactly does dirt form on aircraft? My first thought was pollution, but that didn't seem right. Any ideas?

Have you seen images of the amount of dirt thrown into the air by wind storms in the southwest US. PHX has been closed at times because the dirt in the air is too thick. We have dirt fall on our cars and outdoor furniture here near Dallas from those storms. And on the aircraft at local airports.

There are dozens of volcanos around the world throwing several tons of dirt into the air each month. It goes all around the world.

Right now we are seeing some particulate falling from the wild fires in Colorado and New Mexico.

Pollution is a contributor of course - but the air is filled with dirt from many natural sources.

One reason things seem so fresh after a rain is that the first thing rain does is wash the dirt out of the air.


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 24, posted (2 years 3 weeks 4 days 14 hours ago) and read 3379 times:

Quoting 737tdi (Reply 18):
Hawk21: I see you remember those days, remember changing the outflow valves then? Wow they were a sticky mess plus anything behind the aft bulkhead in the aft. bag bin was coated in gunk.

True....thats when todays aviation Maintenance is much cleaner & more electronic  



Think of the brighter side!
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