777DadandJr
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What's The Red Line For?

Mon Dec 26, 2005 10:57 pm

I have seen this on many a/c and always wondered what it's for. The line can be seen on the front landing gear door. Most of the time, I've seen it in red, which I'm guessing is a warning of some sort, but others I have seen in different colors.
See these examples:

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Photo © Tim Samples - CFI-CFII-MEI





Thanks in advance!

Russ
My glass is neither 1/2 empty nor 1/2 full, rather, the glass itself is twice as big as it should be.
 
aogdesk
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RE: What's The Red Line For?

Mon Dec 26, 2005 11:33 pm

Its a nose gear limit indication for the pushback driver. Depending on the condtions and the airframe, you can damage the towbar, the nose gear, or both.
 
777DadandJr
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RE: What's The Red Line For?

Mon Dec 26, 2005 11:39 pm

Thanks Aogdesk,
I knew it had to be some kind of warning.
Thanks!
Russ
My glass is neither 1/2 empty nor 1/2 full, rather, the glass itself is twice as big as it should be.
 
amtrosie
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RE: What's The Red Line For?

Tue Dec 27, 2005 12:39 am

The lines on the engine cowlings usually denote the area which is extremely dangerous to the individual when engines are in operation.
 
Matt72033
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RE: What's The Red Line For?

Tue Dec 27, 2005 2:01 am

Quoting Aogdesk (Reply 1):
Its a nose gear limit indication for the pushback driver. Depending on the condtions and the airframe, you can damage the towbar, the nose gear, or both.

just to add to that....you can turn beyond this max tow angle line if you disconnect the torsion links on the nose gear!
 
aya734
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RE: What's The Red Line For?

Tue Dec 27, 2005 2:15 am

A RED line painted on the Nose Gear doors indicates the MAXIMUM Turning Angle of the nose gear during tow.  duck 
 
EMBQA
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RE: What's The Red Line For?

Tue Dec 27, 2005 3:34 am

Quoting Matt72033 (Reply 4):
you can turn beyond this max tow angle line if you disconnect the torsion links on the nose gear!

Not in any case I know of. If you go beyond the tow bar max turning indication, you need to perform a special inspecion....and most likely will blow out the seals. Also, the only aircraft that has a torque link that I know of that has a pin to pull is the CRJ.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
Skydrol
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RE: What's The Red Line For?

Tue Dec 27, 2005 3:48 am

Is the max turn angle also indicated by the vertical red line on the fuselage by the pitot tubes (shown in the same photo), or does this represent something else?


On the door and fuselage here:

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Photo © Tim Samples - CFI-CFII-MEI





Only on the door here:

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Photo © Tim Goodwin



LD4
∙ ---{--« ∙ ----{--« ∙ --{-« ∙ ---{--« ∙ --{--« ∙ --{-« ∙ ----{--« ∙
 
September11
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RE: What's The Red Line For?

Tue Dec 27, 2005 3:48 am

See what happened to this A320 - after a tug overstressed the nose gear. Where is the "red line" on this plane?  wink 


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Photo © Paul Loughnane







[Edited 2005-12-26 19:54:16]
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fr8mech
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RE: What's The Red Line For?

Tue Dec 27, 2005 4:42 am

Quoting EMBQA (Reply 6):
Not in any case I know of. If you go beyond the tow bar max turning indication, you need to perform a special inspecion....and most likely will blow out the seals. Also, the only aircraft that has a torque link that I know of that has a pin to pull is the CRJ.

Off hand, the B727 and the DC8 both have torque links that must be disconnected in order to tow. Though I have seen some of both type with bypass valves.

Also, I believe I have read in the various AMM's of some of the aircraft I've worked that you can exceed the tow angle limits if you disconnect the links. That includes those without the quick disconnect features. I'll get into the AMM's tomorrow.
When seconds count...the police are minutes away.
 
Tristarsteve
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RE: What's The Red Line For?

Tue Dec 27, 2005 5:12 am

If you disconnect the torque links on a Tristar (easy disconnect pins) you can turn the nose gear through 360deg, subject to the oleo extension being normal.
 
aogdesk
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RE: What's The Red Line For?

Tue Dec 27, 2005 6:41 am

Quoting Fr8mech (Reply 9):
Off hand, the B727 and the DC8 both have torque links that must be disconnected in order to tow. Though I have seen some of both type with bypass valves.

And I believe that depending on the config, you can rotate the nose gear 360* on the B727 if you disconnect the taxi light wiring along with the links. Ain't steering bypass levers nice?
 
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HAWK21M
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RE: What's The Red Line For?

Tue Dec 27, 2005 6:19 pm

Quoting Matt72033 (Reply 4):
just to add to that....you can turn beyond this max tow angle line if you disconnect the torsion links on the nose gear

Don't forget the Taxi Light Cable.

Quoting Tristarsteve (Reply 10):
If you disconnect the torque links on a Tristar (easy disconnect pins) you can turn the nose gear through 360deg, subject to the oleo extension being normal.

Does the L1011 have a Taxi light mounting on the Lower Oleo Cylinder.

Quoting Skydrol (Reply 7):
On the door and fuselage here:

Why on the Fuselage.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
mikeyCpvd
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RE: What's The Red Line For?

Wed Dec 28, 2005 5:04 am

Quoting Skydrol (Reply 7):
Is the max turn angle also indicated by the vertical red line on the fuselage by the pitot tubes (shown in the same photo), or does this represent something else?

That's a warning for the jetway drivers to steer clear of those particular probes. Don't wanna swing the bridge past that line (since you won't get a clean alignment with the L1 door anyway) or else you risk damaging those components.
Some cats think i'm 6 feet, I'm so deep; I can get d-d-down like a pessimist - Common
 
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HAWK21M
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RE: What's The Red Line For?

Wed Dec 28, 2005 3:03 pm

Quoting MikeyCpvd (Reply 13):
That's a warning for the jetway drivers to steer clear of those particular probes

Is it on All Doors.
Out here its not present.So I guess its optional.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
KC135R
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RE: What's The Red Line For?

Fri Dec 30, 2005 3:09 pm

Quoting Amtrosie (Reply 3):
The lines on the engine cowlings usually denote the area which is extremely dangerous to the individual when engines are in operation.

True - specifically it indicates the turbine plane of rotation
 
abbs380
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RE: What's The Red Line For?

Fri Dec 30, 2005 4:44 pm

Where I work there are bold (big) red lines on the fuselage fwd and aft of both the R1 & L1 doors. These indicate where the entry stairs must be placed to clear the AOA probes and also to prevent the doors from hitting the entry stairs as they swing forward when opened.
 
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HAWK21M
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RE: What's The Red Line For?

Fri Dec 30, 2005 5:02 pm

Quoting KC135R (Reply 15):
True - specifically it indicates the turbine plane of rotation

Shouldn't it denote Line not to be crossed when working near running Engine.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
KC135R
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RE: What's The Red Line For?

Sat Dec 31, 2005 6:23 am

Quoting HAWK21M (Reply 17):
Shouldn't it denote Line not to be crossed when working near running Engine.

Yes, the turbine plane of rotation is the area you want to avoid when the engine is running. That's because if there is an uncontained turbine failure that is the area that parts would come flying from.
 
Matt72033
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RE: What's The Red Line For?

Sat Dec 31, 2005 8:32 am

Quoting KC135R (Reply 18):
Yes, the turbine plane of rotation is the area you want to avoid when the engine is running. That's because if there is an uncontained turbine failure that is the area that parts would come flying from.

i thought they were a "dont step forard of this or you'll get sucked in" line
 
amtrosie
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RE: What's The Red Line For?

Sat Dec 31, 2005 10:07 am

Quoting Matt72033 (Reply 19):
i thought they were a "dont step forard of this or you'll get sucked in" line

It is. The Boeing MM emphatically states that those areas are to be avoided "during powerplant operation", and to avoid these inlet areas.

Quoting KC135R (Reply 15):
True - specifically it indicates the turbine plane of rotation

My handy-dandy "Dictionary of Aeronautical Terms" (ASA Publication 1998)
PLANE OF ROTATION: THE PLANE IN WHICH THE ROTOR BLADES TRAVEL. refering to helicopter rotor; The plane of rotation is perpendicular to the rotor shaft...... Again, my search of the Boeing MM calls out no such term. I have NEVER heard it referenced to turbines.


I hate to spout the facts, but....... no, I always state the facts or else there is not STATEment.
 
KC135R
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RE: What's The Red Line For?

Sat Dec 31, 2005 5:38 pm

Quoting Amtrosie (Reply 20):
Again, my search of the Boeing MM calls out no such term. I have NEVER heard it referenced to turbines.

Hmmm...well that is what I have always heard as an aircraft maintainer for 10+ years in the USAF, but that doesn't necessarily mean anything in and of itself - there are lots of myths and half-truths out there.

But also, our ground air carts (which have their engine intake on the top) are marked with red lines on the side that specifically say "danger - plane of rotation".
For example:




I'll have to double check the tech data when I go back to work, I could be wrong but I am almost certain that is what that line means.
 
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HAWK21M
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RE: What's The Red Line For?

Sat Dec 31, 2005 6:00 pm

Quoting Matt72033 (Reply 19):
Quoting KC135R (Reply 18):
Yes, the turbine plane of rotation is the area you want to avoid when the engine is running. That's because if there is an uncontained turbine failure that is the area that parts would come flying from.

i thought they were a "dont step forard of this or you'll get sucked in" line

Thats what I was aware of too.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
ReidYYZ
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RE: What's The Red Line For?

Sat Dec 31, 2005 7:33 pm

Quoting Matt72033 (Reply 19):
i thought they were a "dont step forard of this or you'll get sucked in" line

I concur. The following will show, it is not a company thing, it's an engine manufacturer warning thing.


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HAWK21M
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RE: What's The Red Line For?

Sat Dec 31, 2005 10:27 pm

The Pic on the right depicts the Vertical line,the Man Figure with Red line diagonally accross, the Plan view of the Engine Danger zones & a Warning sign in Print.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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CCA
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RE: What's The Red Line For?

Sat Dec 31, 2005 11:04 pm

Quoting EMBQA (Reply 6):
Also, the only aircraft that has a torque link that I know of that has a pin to pull is the CRJ.

The 747 has a torque link disconnect pin as well.

Quoting KC135R (Reply 15):
True - specifically it indicates the turbine plane of rotation

Except the turbines are at the back in this case.
P1 in A330, A340, A346, B742, B744, B748.
 
SFOMB67
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RE: What's The Red Line For?

Sun Jan 01, 2006 3:37 pm

Getting back to disconnecting N/G torque links, I know UAL's 767's have quick disc pins on the torue links and elect connectors on the -322 for the taxi lite. I believe this may also be an airline ordered option. as I have seen 767 N/G's w/o quick disc. (probably a vendor gear during gear change) that had to changed over to quick disc.
Not as easy as originally perceived
 
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HAWK21M
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RE: What's The Red Line For?

Mon Jan 02, 2006 1:58 am

Cool it Folks.Lets stick to the topic.Relax its a New year.
Comming to the topic.Anyone having a Link or Pics to a closeup view of these Engine markings.Is it common on all types or does it differ slightly.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Matt72033
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RE: What's The Red Line For?

Mon Jan 02, 2006 3:14 am


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Photo © Simon Wong
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Photo © Erwin



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Photo © Ivan Coninx - Brussels Aviation Photography
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Photo © Ariel Shocron

 
KC135R
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RE: What's The Red Line For?

Mon Jan 02, 2006 5:49 am

Those 4 pictures do make it look like exactly what you guys are saying (which again - might very well be 100% right). But I also found this picture, which seems to clearly show one line as an intake hazard and a second line almost halfway back that means something else. The KC-135's (also CFM56 engines) I work also have the line not quite halfway back on the engine, which may or may not be too far to indicate an intake danger - which, according to some Boeing info I found on the web, is normally about 4-5 feet behind the intake, depending on engine type.


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Photo © Sergio Mota Aviation Photography of Mexico
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Photo © BigSkyBirds



At any rate, I thought our tech data indicated what I said before, but maybe not, I will check when I go back to work next week and let you know either way.

[Edited 2006-01-01 22:08:20]
 
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HAWK21M
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RE: What's The Red Line For?

Mon Jan 02, 2006 3:24 pm

The B737NGs have got a red line on the Fuselage Aft of the Entry doors to indicate Danger zone line during High power Grd Run ups.
regds
MEL
I may not win often, but I damn well never lose!!! ;)

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