sleekjet
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Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 5:33 am

This may appear as an effort to get cheap hits, but I'll press on. What is the lever with the red circle around it...and what is the significance of the yellow dot?


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CaptOveur
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 5:47 am

I think the lever is an angle of attack sensor.. I may be wrong though... I have no idea what the yellow dot is.. A guess is maybe an indicator for the status of the entry door.

I am also not a mechanic or pilot.

[Edited 2005-03-29 21:47:49]
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Fly2HMO
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 5:54 am

Static port?
 
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Starlionblue
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 6:01 am

Just as FLY2HMO, I'm going to guess it's part of the pitot/static system. Where's SlamClick when you need him?
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320tech
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 6:14 am

The device in the red circle is an angle of attack sensor.

Red, yellow, and green dots are blow out indicators for fire extinguishing systems and oxygen systems. Oxygen systems usually use green dots in my experience, though the placement of this one suggests that it could be the crew oxygen system.

The way they work is that there's a line from the bottle (O2 or fire ext) leading to the disk. If the bottle overheats or is fired, the disk gets blown out, giving an obvious indication that the bottle is empty.

Now, this could be something else on the MD-82 - I'm not familiar with it. But that's what it looks like to me.
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troubleshooter
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 6:19 am

It´s just a guess, too. It looks like a blow out disc which indicates an overpressure condition in its related system.

The "lever" with the red circle around is definately an AOA sensor.

Where are the MD 80 experts???
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danman
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 7:16 am

You have collectively got it right, O2 blow out indicator and AOA sensor 100%
 
SlamClick
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 8:21 am

Quoting Starlionblue (Reply 3):
Where's SlamClick when you need him?

Slam was looking for another MD-80 manual. The one nearest to hand did not depict the yellow spot.

Best I can recall DC-9/MD-80 had the oxygen blowout disk (green) on the lower right fuselage, just forward of the bag pit and very near the bottle.

A yellow blowout disk would be for overpressure discharge of the fire bottles but that should be somewhere within one airplanelength of the fire extinguishing system - in other words, near the engines and APU.

It also looks too big to be one of these plastic disks as I remember them being no bigger than a nickel. That object seems to be at least two fingers wide, measuring by the captain's hand.

Rain repellant blowout disk?

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Alias1024
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 8:32 am

As said by everyone else, the lever in the red circle is an AOA sensor.

The yellow dot is not a blow out disc. All AA MD-80s have them to help properly align the jetbridge with the aircraft. American paints a line on the floor of the jetbridge, and whoever is driving the jetbridge matches up the line with the yellow dot on the aircraft.
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DeltaGuy
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 8:51 am

Alias1024 got to it first...I was going to say, I had never seen these on the nose of a DL Mad Dog, but instead they carry an inverted T to help with jetbridge docking, located around the same place as AA's dot.

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DeltaGuy
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skywatch
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 3:10 pm

I'm kind of new at this, but are those fins below the windscreen vortice creators to reduce cockpit wind noise? I just read around on here to learn, and have never worked on any aircraft at all. Feel free to correct me!

[Edited 2005-03-30 07:10:52]
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bio15
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 3:39 pm

Those under the windscreen are the pitot tubes. I'm almost 100% certain

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Alfredo
 
320tech
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 4:00 pm

All AA MD-80s have them to help properly align the jetbridge with the aircraft.

There ya go. We can all learn something here.

Air Can is putting black and white discs on their A320's, to use with an automated bridge system at Toronto. Same idea.
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
 
Fly2HMO
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 5:03 pm

Quoting Skywatch (Reply 10):
are those fins below the windscreen vortice creators to reduce cockpit wind noise?

They are definitely pitot tubes, but I don't remember why there are three of them.  banghead 
 
FBU 4EVER!
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RE: Explain These Doo-dads On The MD-82

Wed Mar 30, 2005 5:31 pm

There are three pitot tubes forward of the windscreen,one for each pitot/static system (Captain's,First Officer's and the Auxiliary system).

Further down on the fuselage,there are strakes on either side of the fuselage.They serve to smoothen the airflow over the wing at high angles of attack and thus increase rudder effectiveness during flap extension/retraction.The old DC-9-41 has a hydraulically operated flap/rudder throw limiter that limits rudder deflection to 13 degrees under these circumstances.A complicated system that was replaced by strakes from the DC-9-50 onwards.
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n685fe
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RE: Explain These Doo-dads On The MD-82

Fri Apr 01, 2005 3:12 am

The 80's also have a rudder throw limiter, it also has a hyd assisted elevator when you push the stick past a certain number of degrees nose down. I forget the exact number, but it is to help during stalls, the 90's also have this system on the T/E of the engine pylons.
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DeltaGuy
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RE: Explain These Doo-dads On The MD-82

Fri Apr 01, 2005 8:39 am

I believe the strakes on the nose (as well as the ones on the tail) served the same purpose, that is to aid in stall recovery, specifically deep stalls? (I may be criss-crossing some of my facts here)

DeltaGuy
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FBU 4EVER!
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RE: Explain These Doo-dads On The MD-82

Sat Apr 02, 2005 12:09 am

No,the strakes on the nose are for aerodynamic purposes as mentioned.They are also anti-iced by pneumatics on the MD-80 and electrically on the MD-90.The strakes on the nacelles are for stall-recovery purposes by adding more horizontal area in the tail area.The idea is that this will allow the nose to fall somewhat faster than the tail area due to drag,thus making deep stall recovery more likely.These strakes are not heated in any way.
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