upsmd11
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AA MD80 Fuselage Strobes

Wed Oct 12, 2005 8:00 am

The other night I was taxiing in a US A319 at BOS and noticed an AA MD80 arriving at a gate. I noticed the red indicator lights on the top and bottom of the MD80 were flashing in unison. This is something that I have only seen 737NG, 757, 767, 777 and newer Airbii do. Did the AA maintenance staff do something to change this or was I seeing an anomaly?

Thanks,
John
 
AsstChiefMark
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RE: AA MD80 Fuselage Strobes

Wed Oct 12, 2005 10:19 am

Strobe power supplies have anywhere from 1 to 6 output jacks. Simultanous or alternating flashes are achieved by simply moving an output cable from one jack to another.

Similar strobe power supplies are used on emergency and maintenance vehicles.



Mark
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HAWK21M
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RE: AA MD80 Fuselage Strobes

Wed Oct 12, 2005 4:39 pm

Quoting Upsmd11 (Thread starter):
I noticed the red indicator lights on the top and bottom of the MD80 were flashing in unison.

I guess You are reffering to the Anticollosion lights on the top & Bottom Fuselage.The Strobe lights are the White Flashing lights at the Wingtips & Tail cone.

Quoting AsstChiefMark (Reply 1):
Simultanous or alternating flashes are achieved by simply moving an output cable from one jack to another.

Any Pics.

regds
MEL
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cdfmxtech
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RE: AA MD80 Fuselage Strobes

Wed Oct 12, 2005 7:47 pm

i believe simultaneous strobes are merely coincidence on those boeing airplanes u mentioned. some planes like the dc10 had a sync circuit to make sure the flash in unison.
 
upsmd11
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RE: AA MD80 Fuselage Strobes

Wed Oct 12, 2005 9:23 pm

Yes I am referring to the anti-collision lights. I notice the small things like that and this MD80 of AA never did falter from being in sync. I'm just wondering if some new circuitry could have been put in to make it do this?

John
 
SPREE34
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RE: AA MD80 Fuselage Strobes

Thu Oct 13, 2005 2:13 am

Quoting HAWK21M (Reply 2):
I guess You are reffering to the Anticollosion lights on the top & Bottom Fuselage.The Strobe lights are the White Flashing lights at the Wingtips & Tail cone.

The "anti-collision lights" in the MD80s case happen to be strobes. LEDs are coming to an aircraft near you soon as well.
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HAWK21M
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RE: AA MD80 Fuselage Strobes

Thu Oct 13, 2005 3:14 am

Quoting SPREE34 (Reply 5):
The "anti-collision lights" in the MD80s case happen to be strobes

The reference is Anticollosion lights.Strobe lights are a Different location.
regds
MEL
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AsstChiefMark
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RE: AA MD80 Fuselage Strobes

Thu Oct 13, 2005 8:55 am

Quoting HAWK21M (Reply 2):
The Strobe lights are the White Flashing lights at the Wingtips & Tail cone.

Many anticollision beacons ARE strobes. Some are LED. Not all are rotating or oscillating beacons.

Strobe:


LED:


I've seen the LED beacons in use. They are so much brighter than any other beacon. Their flash patterns are very unique and distinctive.

Some white wingtip lights are oscillating "beacons." They contain a light bulb with a filament and a reflector that "wobbles" back and forth. That's in addition to the typical red and green nav lights. I've seen them on a few 727-100's and some NW DC-9's.

Mark

[Edited 2005-10-13 01:57:55]
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cdfmxtech
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RE: AA MD80 Fuselage Strobes

Thu Oct 13, 2005 12:59 pm

To answer the posters question, while I can't speak for EVERY MD-80, the ones I worked on didn't have any synchronizing circuit. One CB powers both Upper and Lower Anticollision lights. The power should energize both lights simultaneously and if the respective assemblies are working correctly, then they will flash in unison. But if one of the assemblies' timing circuit is off a bit, then u might get stagger btwn lights.
 
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HAWK21M
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RE: AA MD80 Fuselage Strobes

Thu Oct 13, 2005 3:03 pm

Quoting AsstChiefMark (Reply 7):

Agreed Mark.....
I was refering to the Terminology to name the Light based on the location/purpose & not the operating principle.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
boeing767mech
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RE: AA MD80 Fuselage Strobes

Fri Oct 14, 2005 4:04 pm

I have been working for AA maint now for 6 years and have aways seen the Anticollision lights flashing together. Now if the wing anticollison lights are flashing on the ground at the gate you have a problem since these work
throught the air/ground relays. And the MD-80s do not have strobes on the tail.

David
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LMP737
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RE: AA MD80 Fuselage Strobes

Fri Oct 14, 2005 10:56 pm

What's really fun about the upper strobe on the MD-80 is when you have to change one. Unlike Boeing aircraft where you can change the strobe from inside the cabin on the MD-80 you have to do it from the outside. Which means getting a boom lift and crawling out onto the fuselage.
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HAWK21M
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RE: AA MD80 Fuselage Strobes

Fri Oct 14, 2005 11:37 pm

Quoting LMP737 (Reply 11):
Which means getting a boom lift and crawling out onto the fuselage.

Given the option it would be easier from the Outside,considering the Access.Only dont slide off the Fuselage  Smile
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Electech6299
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RE: AA MD80 Fuselage Strobes

Sat Oct 15, 2005 11:40 am

Quoting CdfMxTech (Reply 3):
i believe simultaneous strobes are merely coincidence on those boeing airplanes u mentioned. some planes like the dc10 had a sync circuit to make sure the flash in unison.

Yes, the old sync circuits....I never saw a DC-10 unplugged, but I can just imagine as many a lighting system used them. The number of steps to follow in stepping up the power for the light and down for the control circuit was mind-boggling. Too many moving parts, too...

With the newer LEDs the circuit will have just a low-voltage logic chip to send a low voltage "trigger" signal -- a step up from the logic circuits triggering the high-voltage rapid discharge flash...But neither one should go "out of sync"- timing circuits are inherent. Assuming more than one signal box on a power supply circuit (or even 2 differenct circuits), they might power up slightly off. But they will never flash at a different rate, unless at extremely different temperatures.

Now the old rotating beacons.. Sure, they went out of sync...again, too many moving parts. But they worked good for many years...

And I must say, I got quite a kick out of the variant terminology dialogue... function vs. operation!!!  rotfl  I love seeing the differences in language.

Yeah, Mel, I call the anti-cols beacon's too...I guess that's old mariner's terminology. To me, if it's a navigation warning in a horizontal plane it's a beacon, if it's flashing for some other reason it's (usually) a strobe. I don't try to distinguish by operation, not enough people know the difference between a beacon and a strobe, and if you say LED most people think of a digital clock...But everyone seems to know that the light in a lighthouse is a beacon, and it tells you where (not) to go. But among other elec techs I guess I just say lamp...unless it's an LED.

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