Mr Spaceman
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What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 12:31 am

Hi guys.

As you can see, the B737-6 in these 2 shots has a very prominent dark stain on it's belly that's obviously starting from the nosegear wheel well area.

My question is ..... What's causing this stain?

I suspect it's caused by either a hydraulic fluid leak (for the nosegear steering, etc), or maybe it's from rubber flying up off the nosegear tires apon landing.


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When this same 737 was clean ....
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There are many photos in the database that show airliners with dark stains trailing back from the nosegear, and they all seem to be aircraft that are low to the ground on their short gear struts. That's why I thought of burning rubber flying off the nose wheel tires and hitting the fuselage as a possible cause.


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Chris  Smile
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futureuapilot
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 1:26 am

Hey Chris. I clean planes at the airport. That is just grease and other fluids dripping out of the aircraft. There's alot of grease and such, you really notice it on the King Air's and Cessnas. Whoever decided to paint King Air's white... I wanna have a talk with them. Normally we would clean them off, but it looks like there's alot of accumulation there, might be a bigger job! I'm not an airliner expert, but i'm assuming they are the same as the king airs.

-Sam
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Mr Spaceman
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 2:25 am

Hello FutureUApilot.

Thanks for your reply. Big grin


Quoting FutureUApilot (Reply 1):
That is just grease and other fluids dripping out of the aircraft. There's a lot of grease and such



Quoting FutureUApilot (Reply 1):
I'm not an airliner expert, but I'm assuming they are the same as the king airs.

OK, so it's just grease & fluids that's leaking out of the wheel well and getting sprayed aft by airflow while flying.

These 3 shots show the hydraulic & oil lines, etc, in both the nose & main gear wheel wells on a 737. Many airliners have dark stains streaming backwards from the main gear too. When you see all the fluid lines in the main wheel wells .... I'm not surprised.


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I must say I'm still wondering why these nosegear stains appear mostly on aircraft that sit low to the ground ..... thus my thoughts about flying rubber. Don't airliners with tall gear struts leak fluids too?


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Chris  Smile
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citation501sp
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 11:22 am

Don't forget these aircraft speed down a runway that is covered in Rubber from landing aircraft.With the Sun Beatting down on the touchdown marks the rubber turns into a tar like substance. which easily gets sprayed on the aircraft belly. So what you see is a mix of rubber from tires, from the runway not from the aircraft's tires. Take a business jet that usually gets a bath every few days. A few trips and there is the start of a dirt trail.

It even happens on small aircraft. The inside of wheel pants is usually black and isn't painted that color.

501SP
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EMBQA
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 11:35 am

These 3 shots show the hydraulic & oil lines, etc, in both the nose & main gear wheel wells on a 737

That is a factory fresh aircraft. I'll bet you anything a month later it didn't look anything like that..!!
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videns
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 12:22 pm

maybe brake dust from stopping the wheels before they enter the wheel well?
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DeltaGuy
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 12:35 pm

Stand under a 767 and let your head rub along the belly of it (for guys like me who are 6'2", it's about the right height). Guarantee you'll get a nice goopy, oily mess in your scalp. Seems like there's a grease trail running from the main mounts all the way to the APU on some of these birds. It's a combination of the tar-like runway crap, hydraulic fluid, oil, etc...pretty sticky.

DeltaGuy
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Mr Spaceman
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 4:00 pm

>> Citation501SP, EMBQA, Videns, & DeltaGuy, Thank You for your replies.

Quoting EMBQA (Reply 4):
That is a factory fresh aircraft. I'll bet you anything a month later it didn't look anything like that..!!

I agree. I'm sure that 737's wheel wells normally look like this .... or worse!


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Quoting DeltaGuy (Reply 6):
t's a combination of the tar-like runway crap, hydraulic fluid, oil, etc...pretty sticky.

Well, I believe the above statement best explains what the causes of these stains are, with the addition of brake dust adding to the stains behind the main gear on the airliners. I'm sure the airliners with tall gear struts have cleaner bellies because the rubber flying up from the runways doesn't reach that high.

This Boeing -757 is the only airliner with tall gear struts that I could find that has a stain behind the nosegear that's visible from a distance.


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Quoting DeltaGuy (Reply 6):
Seems like there's a grease trail running from the main mounts all the way to the APU on some of these birds.

Just like this A320 .... what a mess!


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Thanks again for sharing your thoughts guys. Big grin


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MD11Engineer
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 10:02 pm

The movable joints on the landing gear get regularly lubricated by mechanics using grease guns. There are grease pins on each joint, into which greased is forced under pressure by the grease gun (usually during A-checks). The old grease gets pressed out of the gaps of the joint. There are lazy §#(% of mechanics, who don't bother to use a cleaning rag to remove the excess grease. During flight the grease gets then blown all over the place by the slip stream.
Some of the greases used are hygroscopic, like Aeroshell grease 7 and tend to run. Obviously the grease on the belly of the plane causes dirt and dust from the air to stick on it, giving it the black appearance.

Jan
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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 18, 2005 10:05 pm

Def a combination of Grease,water & Hydraulic fluid compounded by Splashing Water & rubber from the Gear.
When the Surface aft gets rougher,cleaning gets worse.
regds
MEL
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IFixPlanes
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RE: What's Caused These Stains - Rubber Or Fluid?

Fri Aug 19, 2005 4:17 pm

Quoting MD11Engineer (Reply 8):
...There are grease pins on each joint...

Here you can see the lower end component servicing:


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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Fri Aug 19, 2005 4:28 pm

Best way to reduce these stains would be more frequent & regular Washes.
regds
MEL
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MD11Engineer
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RE: What's Caused These Stains - Rubber Or Fluid?

Fri Aug 19, 2005 7:30 pm

Quoting IFixPlanes (Reply 10):
Quoting MD11Engineer (Reply 8):
...There are grease pins on each joint...

Here you can see the lower end component servicing:

Thanks, but I've been wielding the grease gun often enough myself (not my favourite job, on some aircraft you look like a pig when you are finished).

Quoting HAWK21M (Reply 11):
Best way to reduce these stains would be more frequent & regular Washes.
regds

Aircraft washes cost money. Also, at some airports it is not permitted to wash aircraft due to enviromentaly reasons, since they don't have special water / oil / grease seperators installed in the ramp drain sytem.

Many airines would only wash their planes if they could get it done for free.

Jan
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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Fri Aug 19, 2005 9:27 pm

Quoting MD11Engineer (Reply 12):
Also, at some airports it is not permitted to wash aircraft due to enviromentaly reasons, since they don't have special water / oil / grease seperators installed in the ramp drain sytem.

Interesting.
At Bom 9W Has an Entire Team devoted to Interior & Exterior Cleaning.
regds
MEL
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MD11Engineer
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RE: What's Caused These Stains - Rubber Or Fluid?

Fri Aug 19, 2005 10:35 pm

In CGN, the only place where aircraft are allowed to receive external cleaning in in the Hangar of LH Cityline, but they only allow their own planes to be washed inside.
Whenever we had a fuel spill on the ramp, the first job of the fire brigade was to prevent the fuel from running into the ramp drains, because they were not connected to a fuel / oil / water seperator and the pollution would have run straight into the river.

Jan
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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Fri Aug 19, 2005 10:49 pm

Quoting MD11Engineer (Reply 14):
prevent the fuel from running into the ramp drains, because they were not connected to a fuel / oil / water seperator and the pollution would have run straight into the river.

Why Wasn't Installation of a Filter considered.
regds
MEL
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futureuapilot
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RE: What's Caused These Stains - Rubber Or Fluid?

Wed Aug 24, 2005 1:37 am

Quoting HAWK21M (Reply 15):
Why Wasn't Installation of a Filter considered.

Um. Cost. Those aren't cheap and need replacing often. Plus you have to create a way to get to them to service them.

-Sam
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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Wed Aug 24, 2005 9:06 pm

Quoting FutureUApilot (Reply 16):
Those aren't cheap and need replacing often. Plus you have to create a way to get to them to service them.

Considering the use of the system by most Airlines,I would think the Investment was worth it.
regds
MEL
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Electech6299
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 25, 2005 5:52 am

Quoting HAWK21M (Reply 15):
Why Wasn't Installation of a Filter considered.

Don't forget that you are talking about a rainwater drain that serves a massive surface area. Think of the volume of water that runs down those drains in the event of even 1/2" of rain....and you see that filtering rainwater is not practical. Now in aircraft service bays, it's a different story. But initial civil engineering looks at moving rainwater from the AOA just like from a city park or multi-lane highway. You wouldn't think of filtering all those storm drains, just because of the occasional oil or fuel leak. (although that is exactly where the majority of surface and groundwater pollution originates)

The reference to containing the leak to prevent entrance into the storm sewer is a simple case of spill response- any potential pollutant spilled where it could impact the environment gets the same treatment (if the local authority is accountable...)

So the cost-effective solution is to create designated, engineered areas for high-pollution operations (i.e. washing the muck off of the belly), and just practice spill response for the occasional (hopefully unintentional) release that could affect the storm system. Apparently the service companies don't feel that the demand for a clean belly is strong enough to make a profit by installing appropriate service bays (with grease traps) at every airport.
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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 25, 2005 4:32 pm

Quoting Electech6299 (Reply 18):
Apparently the service companies don't feel that the demand for a clean belly is strong enough to make a profit by installing appropriate service bays (with grease traps) at every airport.

I guess it varies at different places on the Globe.Understandably so.
regds
MEL
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MD11Engineer
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 25, 2005 8:17 pm

The airlone we were taking care of didn't even want to pay us or a gang of cleaners to clean their planes. They expected us to do it for free, even though their pilots complained (as well as us), that it was very hard to look for leakages under the dirt. They told us that if the dirt disturbed us, we would have to clean it away at our own expense.
Do you think they want to pay for a proper waste water treatment plant? Only LH Cityline had such a plant installed in their MX hangar, but they wouldn't let anybody else use it.

Jan
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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 25, 2005 9:06 pm

Quoting MD11Engineer (Reply 20):
The airlone we were taking care of didn't even want to pay us or a gang of cleaners to clean their planes

What did the deal involve.May be it can be taken up at a higher level.
Most Pax consider clean & shiny Aircraft to be safe.Im surprised at the company attitude.Is it a Cargo Airline.
regds
MEL
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MD11Engineer
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 25, 2005 9:45 pm

It was an American cargo airline. LH keep all their planes clean, even the freighters. The planes get washed externaly at each A-check (depending on the flying hours appr. every 6 weeks).

Jan
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HAWK21M
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RE: What's Caused These Stains - Rubber Or Fluid?

Thu Aug 25, 2005 10:51 pm

Quoting MD11Engineer (Reply 22):
It was an American cargo airline

I thought so.Their logic would be Cargo does not notice the type of Aircraft & how clean it is  Smile
regds
MEL
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