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What's The Red Line For?  
User currently offline777DadandJr From United States of America, joined Feb 2005, 1516 posts, RR: 12
Posted (8 years 8 months 3 weeks 6 days 15 hours ago) and read 4784 times:

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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Click here for bigger photo!

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.
30 replies: All unread, showing first 25:
 
User currently offlineAogdesk From United States of America, joined Jun 2004, 935 posts, RR: 3
Reply 1, posted (8 years 8 months 3 weeks 6 days 14 hours ago) and read 4757 times:

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.

User currently offline777DadandJr From United States of America, joined Feb 2005, 1516 posts, RR: 12
Reply 2, posted (8 years 8 months 3 weeks 6 days 14 hours ago) and read 4751 times:

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.
User currently offlineAmtrosie From United States of America, joined Jan 2005, 274 posts, RR: 0
Reply 3, posted (8 years 8 months 3 weeks 6 days 13 hours ago) and read 4730 times:

The lines on the engine cowlings usually denote the area which is extremely dangerous to the individual when engines are in operation.

User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 4, posted (8 years 8 months 3 weeks 6 days 12 hours ago) and read 4701 times:

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!


User currently offlineAya734 From Indonesia, joined Dec 2005, 2 posts, RR: 0
Reply 5, posted (8 years 8 months 3 weeks 6 days 12 hours ago) and read 4694 times:

A RED line painted on the Nose Gear doors indicates the MAXIMUM Turning Angle of the nose gear during tow.  duck 

User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 6, posted (8 years 8 months 3 weeks 6 days 10 hours ago) and read 4655 times:

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"
User currently offlineSkydrol From Canada, joined Oct 2003, 972 posts, RR: 10
Reply 7, posted (8 years 8 months 3 weeks 6 days 10 hours ago) and read 4643 times:

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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Click here for bigger photo!

Photo © Tim Samples - CFI-CFII-MEI





Only on the door here:

View Large View Medium
Click here for bigger photo!

Photo © Tim Goodwin



LD4



∙ ---{--« ∙ ----{--« ∙ --{-« ∙ ---{--« ∙ --{--« ∙ --{-« ∙ ----{--« ∙
User currently offlineSeptember11 From United States of America, joined May 2004, 3623 posts, RR: 21
Reply 8, posted (8 years 8 months 3 weeks 6 days 10 hours ago) and read 4643 times:

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]


Airliners.net of the Future
User currently offlineFr8mech From United States of America, joined Sep 2005, 5443 posts, RR: 14
Reply 9, posted (8 years 8 months 3 weeks 6 days 9 hours ago) and read 4609 times:

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.
User currently offlineTristarsteve From Sweden, joined Nov 2005, 4008 posts, RR: 33
Reply 10, posted (8 years 8 months 3 weeks 6 days 9 hours ago) and read 4592 times:

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.

User currently offlineAogdesk From United States of America, joined Jun 2004, 935 posts, RR: 3
Reply 11, posted (8 years 8 months 3 weeks 6 days 7 hours ago) and read 4566 times:

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?


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 12, posted (8 years 8 months 3 weeks 5 days 19 hours ago) and read 4409 times:

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



Think of the brighter side!
User currently offlineMikeyCpvd From United States of America, joined Aug 2003, 162 posts, RR: 2
Reply 13, posted (8 years 8 months 3 weeks 5 days 9 hours ago) and read 4299 times:

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
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 14, posted (8 years 8 months 3 weeks 4 days 23 hours ago) and read 4206 times:

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



Think of the brighter side!
User currently offlineKC135R From United States of America, joined Apr 2005, 727 posts, RR: 4
Reply 15, posted (8 years 8 months 3 weeks 2 days 23 hours ago) and read 4036 times:

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


User currently offlineAbbs380 From United States of America, joined Mar 2005, 120 posts, RR: 0
Reply 16, posted (8 years 8 months 3 weeks 2 days 21 hours ago) and read 4012 times:

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.

User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 17, posted (8 years 8 months 3 weeks 2 days 21 hours ago) and read 4007 times:

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



Think of the brighter side!
User currently offlineKC135R From United States of America, joined Apr 2005, 727 posts, RR: 4
Reply 18, posted (8 years 8 months 3 weeks 2 days 7 hours ago) and read 3929 times:

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.


User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 19, posted (8 years 8 months 3 weeks 2 days 5 hours ago) and read 3895 times:

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


User currently offlineAmtrosie From United States of America, joined Jan 2005, 274 posts, RR: 0
Reply 20, posted (8 years 8 months 3 weeks 2 days 4 hours ago) and read 3882 times:

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.


User currently offlineKC135R From United States of America, joined Apr 2005, 727 posts, RR: 4
Reply 21, posted (8 years 8 months 3 weeks 1 day 20 hours ago) and read 3819 times:

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.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 22, posted (8 years 8 months 3 weeks 1 day 20 hours ago) and read 3811 times:

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



Think of the brighter side!
User currently offlineReidYYZ From Kyrgyzstan, joined Sep 2005, 536 posts, RR: 0
Reply 23, posted (8 years 8 months 3 weeks 1 day 18 hours ago) and read 3798 times:

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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Photo © Paul Markman
View Large View Medium
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Photo © Robin Zartos



User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 24, posted (8 years 8 months 3 weeks 1 day 15 hours ago) and read 3774 times:

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



Think of the brighter side!
25 CCA : The 747 has a torque link disconnect pin as well. Except the turbines are at the back in this case.
26 Sfomb67 : 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 ta
27 HAWK21M : 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 markin
28 Post contains images Matt72033 :
29 Post contains images KC135R : 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, w
30 HAWK21M : 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
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