Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
B777 Main Gear Steering Inop - WX?  
User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Posted (8 years 4 months 1 week 1 day 15 hours ago) and read 4650 times:

On a recent flight from hell, er I mean ORD, to DEN, on a UA 772, I heard a strange comment on channel 9. We pushed back, deiced, and taxiied out, but due to substantial delays, we had to return to the gate for deicing. A gate was not available, and the holding areas were full, so we just stopped on a small connector taxiway. The pilots never shut the engines down, but we were there for almost 3 hours. When we finally got to move again, the captian told the ground controller "We just lost the main gear steering, so we can't make that next turn. We'll have to go down farther." I was wondering, could the loss of the main gear steering have been due to snow/ice accumulation? If not, then what? Maintenance never checked out the plane, so I wouldn't think it was a MEL item, and we eventually (9 hours later) took off on the same plane. How does this system work, and what are its usual failure and recovery modes? Thanks!


Position and hold
26 replies: All unread, showing first 25:
 
User currently offline777WT From United States of America, joined Jan 2005, 874 posts, RR: 1
Reply 1, posted (8 years 4 months 1 week 1 day 14 hours ago) and read 4623 times:

I wouldn't think it would've been from the snow/ice accumulation. The main gear steering allows the rear 2 wheels on each mains to turn for tight turns and to ease up the stress on the main gear.
Failure mode would prob just lock the gear in line with the other wheels. I wouldn't know, a 777 tech could explain better.

Sounded like UA burned up alot of fuel in this case.


User currently offlineCdfMxTech From United States of America, joined Jul 2000, 1338 posts, RR: 27
Reply 2, posted (8 years 4 months 1 week 1 day 12 hours ago) and read 4599 times:

Main gear Steering uses inputs from the Nose Gear steering system to provide steering for the aft main gear wheels. The 777 monitors itself and if it determines different levels of faults that may exist in the system. The level of message will determine whether the crew can go or not. For instance, if the wheels were not locked and centered, then an advisory message will let them know about it. If they were to advance the throttles to take off position, then a higher level WARNING message would alert them.
If an actuator failed in the closed position, it would be a status message, and returning to the gate might not be necessary.

The Main gear Steering system is placardable, but maintenance must ensure the system is locked. The lockout is done on the gear.

There is a way to access a display in the flightdeck which will show the position of the MGS steering system. Not sure if it's on the regular pilot synoptinc pages ot on maintenance pages. Don't work the airplane often enoguh to remmeber that.


User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 3, posted (8 years 4 months 1 week 1 day ago) and read 4519 times:

Quoting Bri2k1 (Thread starter):
Maintenance never checked out the plane, so I wouldn't think it was a MEL item, and we eventually (9 hours later) took off on the same plane.

Wouldn't an MEL entry necessatite a Paperwork Entry.
regds
MEL



Think of the brighter side!
User currently offlineTristarsteve From Sweden, joined Nov 2005, 3930 posts, RR: 34
Reply 4, posted (8 years 4 months 1 week 22 hours ago) and read 4502 times:

Quoting HAWK21M (Reply 4):
Wouldn't an MEL entry necessatite a Paperwork Entry

In my airline, once the aircraft starts to move under its own power then the MEL does not apply. If the crew get a message they can decide to look in the MEL to see what it says, then decide to take off if no maint action is required.


User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 5, posted (8 years 4 months 1 week 21 hours ago) and read 4481 times:

Quoting Tristarsteve (Reply 5):
once the aircraft starts to move under its own power

That's interesting. I don't know what would have applied here. We did return to the gate for refueling, but I could clearly see the aircraft door from where I sat, and no crew member left the plane, nor did a maintenance person board the plane. We eventually pushed back, de-iced again, and took off. I heard no other mention of the MLG steering on the radio (although I could only hear communications with ramp metering and ground, and not the company frequencies.)



Position and hold
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 6, posted (8 years 4 months 1 week 14 hours ago) and read 4430 times:

Quoting Tristarsteve (Reply 5):
In my airline, once the aircraft starts to move under its own power then the MEL does not apply. If the crew get a message they can decide to look in the MEL to see what it says, then decide to take off if no maint action is required

Interesting.Is this SOP in tune with FAA/JAA/CAA of your Countrys regulatory board.
Out here its Different.
regds
MEL



Think of the brighter side!
User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 7, posted (8 years 4 months 1 week 13 hours ago) and read 4424 times:

Quoting Bri2k1 (Reply 6):
nor did a maintenance person board the plane.

surely if fuel was uplifted then an entry into the tech log must be made, also here we have to deliver the fuel card to the captain so he can make his calculations and decide he's happy with what he has!


User currently offlineSabenaboy From Belgium, joined Feb 2001, 187 posts, RR: 2
Reply 8, posted (8 years 4 months 1 week 12 hours ago) and read 4418 times:

Quoting HAWK21M (Reply 7):
Quoting Tristarsteve (Reply 5):
In my airline, once the aircraft starts to move under its own power then the MEL does not apply. If the crew get a message they can decide to look in the MEL to see what it says, then decide to take off if no maint action is required

Interesting.Is this SOP in tune with FAA/JAA/CAA of your Countrys regulatory board.
Out here its Different.
regds
MEL

Hi, this rule is also applicable in my airline. Once we started taxi, we are not obliged anymore to take out the MEL if a failure occurs. Of course, the crew can always decide to do so, if in doubt about a certain failure. Even if the MEL would say that the failure is a no go-item, the crew can still legally decide to continue the flight. For instance, if the Flight date (DFDR) AND the voice recorder (CVR) fail after the taxi has started, the captain may decide to continue the flight. If the failure had occurred during the pushback, a repair would have been necessary before takeoff.

And yes,Hawk, this SOP is in tune with the rules in my country and JAR.

Regards,
Sabenaboy


User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 9, posted (8 years 4 months 1 week 11 hours ago) and read 4413 times:

Quoting Matt72033 (Reply 8):
surely if fuel was uplifted then an entry into the tech log must be made,

United don't have a "tech log". Neither do they have an MEL on the aircraft.

Quoting HAWK21M (Reply 7):
Out here its Different.

No surprise there then.

Quoting Bri2k1 (Thread starter):
Maintenance never checked out the plane, so I wouldn't think it was a MEL item,

Very common that a 777 fixes itself. IOW, status messages come and go regularly. Main gear steering is common, is MELable but requires a maintenance procedure. However, it regularly goes away (the message, that is) all on it's own. No message, nuthin' to fix.


User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 10, posted (8 years 4 months 1 week 6 hours ago) and read 4390 times:

Quoting Charliecossie (Reply 10):
United don't have a "tech log". Neither do they have an MEL on the aircraft.

Pls elaborate Charlie.
Isn't MEL a part of the On board Docs.
regds
MEL



Think of the brighter side!
User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 11, posted (8 years 4 months 1 week 6 hours ago) and read 4387 times:

There is no "tech log" on the aircraft. It's totally computerised.
The only paperwork normally in the cockpit is the Maintenance Release Document which details defects recorded on the previous sector and the action taken, open MEL items and a few other things. The MRD is usually transmitted to the aircraft via ACARS. There is a (never used) paper backup system in case the computer system dies but it's never needed in reality.
Defects are transmitted (via ACARS) by the crew or the CMC (certain status messages). If the defect is a status message that self-erases, the defect disappears from the online tech log automatically.
As there's no tech log, fuel figures cannot be entered into it.
United use a computer printed fuel sheet. Loading fuel is not an engineering function. It's carried out by ramp staff who bring the completed fuel sheet to the cockpit.
There is no MEL on a United 747 or 777. Any EICAS/status messages/defects seen by the crew are transmitted back to the online tech log. If a status message occurs during, for example, taxi to the runway, the crew either call local engineering on VHF or Systems Aircraft Maintenance Control (aka SAM-C) via satcom or ACARS. If SAM says it's a go-er, they go and SAM makes the online tech log entry and defers it. The aircraft receives (again via ACARS) a copy of the MEL placard.
Seems complicated. Is complicated. Works well.


User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 12, posted (8 years 4 months 1 week 5 hours ago) and read 4385 times:

sounds good! paperworks such a huge part of the job here....anything that can cut it down a bit has to be good.

so if there's no paper tech log, does the licenced engineer have to sign anything to release the aircraft? does the captain sign anything to accept the aircraft? or is this all done on the MRD?


User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 13, posted (8 years 4 months 1 week 5 hours ago) and read 4383 times:

Quoting Matt72033 (Reply 13):
does the licenced engineer have to sign anything to release the aircraft?

Electronic "signature" on the MRD. If you aren't qualified, you can't release it.

Quoting Matt72033 (Reply 13):
does the captain sign anything to accept the aircraft?

No, not required.


User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 14, posted (8 years 4 months 1 week 5 hours ago) and read 4376 times:

looks like its the way forward...hopefully it'll be implemented here soon!

User currently offlineCX flyboy From Hong Kong, joined Dec 1999, 6533 posts, RR: 55
Reply 15, posted (8 years 4 months 1 week 4 hours ago) and read 4366 times:

Quoting Charliecossie (Reply 10):
Very common that a 777 fixes itself. IOW, status messages come and go regularly. Main gear steering is common, is MELable but requires a maintenance procedure. However, it regularly goes away (the message, that is) all on it's own. No message, nuthin' to fix

In my years on the 777 I cannot say that I have ever seen a Main Gear Steering message, although you are correct in that sometimes we do get messages which appear and then vanish sometime later, although I would not say that it is regular. Maybe once every 30 flights or so with our fleet. More common is the status message which the engineers reset and then the system passes a check and it is declared serviceable.


User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 16, posted (8 years 4 months 1 week 4 hours ago) and read 4357 times:

Quoting CX flyboy (Reply 16):
a Main Gear Steering message

I wasn't privy to the actual message, of course. I simply overheard the captain tell ground control "we just lost our main gear steering" and, as a result, we couldn't make the very next 90-degree turn, we had to taxi down a ways.

It's interesting that the message would come and go. I assume while it was completely safe, the designers didn't intend for the plane to sit, fully loaded, both engines turning, for 9 hours, in an ice storm, every single flight. That's why I wondered if the steering issue could have been related to the weather. So, I guess I'll never know if it was fixed or not, but I do know we eventually left on the same plane, and I never saw anyone fixing anything mechanical. Thanks for all the responses!



Position and hold
User currently offlineCdfMxTech From United States of America, joined Jul 2000, 1338 posts, RR: 27
Reply 17, posted (8 years 4 months 4 days 23 hours ago) and read 4257 times:

Quoting Bri2k1 (Reply 17):
I wasn't privy to the actual message, of course. I simply overheard the captain tell ground control "we just lost our main gear steering" and, as a result, we couldn't make the very next 90-degree turn, we had to taxi down a ways.

yes, the only way the crew would have knowwn about the loss of MGS is a message. There are no Annunciators for this condition on the 777, just the message.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 18, posted (8 years 3 months 3 weeks 20 hours ago) and read 4122 times:

Quoting CX flyboy (Reply 16):
although you are correct in that sometimes we do get messages which appear and then vanish sometime later

Very comforting Big grin



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineLarspl From Netherlands, joined Apr 2002, 473 posts, RR: 0
Reply 19, posted (8 years 3 months 2 weeks 5 days 8 hours ago) and read 4005 times:

Quoting Bri2k1 (Reply 6):
We did return to the gate for refueling, but I could clearly see the aircraft door from where I sat, and no crew member left the plane, nor did a maintenance person board the plane. We eventually pushed back, de-iced again, and took off. I heard no other mention of the MLG steering on the radio (although I could only hear communications with ramp metering and ground, and not the company frequencies.)

on many a/c types there are more ways to enter and exit the aircraft than the 'normal' doors. i.e.: the A330 has a hatch in de cockpit floor into the bay and another hatch into the 'outside'.



i'm not implying that this happened on your flight, i'm not even sure if it is possible on the 777. Just a reminder that there is so much you don't see in the cabin happening in aviation



I would guess that forward or e/e access is located in the cockpit, and that under the left seat is some sort of hatch.



facebook.com/ddaclassicairlines
User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 20, posted (8 years 3 months 2 weeks 5 days 7 hours ago) and read 3990 times:

Quoting Larspl (Reply 23):
I would guess that forward or e/e access is located in the cockpit, and that under the left seat is some sort of hatch.

Don't guess, you'd be wrong.


User currently offlineLarspl From Netherlands, joined Apr 2002, 473 posts, RR: 0
Reply 21, posted (8 years 3 months 2 weeks 5 days 2 hours ago) and read 3969 times:

Quoting Charliecossie (Reply 24):
Don't guess, you'd be wrong.

alright  Smile

can you tell me where to they do refer?



facebook.com/ddaclassicairlines
User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 22, posted (8 years 3 months 2 weeks 5 days ago) and read 3951 times:

On the triple, the "lower 41" hatch (e&e bay hatch) is just inside door 1 left.
On United, the latch handle (for the hatch) is secured, from above, with a very large screw.


User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 23, posted (8 years 3 months 2 weeks 5 days ago) and read 3945 times:

Quoting Charliecossie (Reply 28):
On the triple, the "lower 41" hatch (e&e bay hatch) is just inside door 1 left.
On United, the latch handle (for the hatch) is secured, from above, with a very large screw.

anyway out through the nose gear bay?
Edit: or into the cargo hold?

[Edited 2006-01-01 20:53:37]

User currently offlineLarspl From Netherlands, joined Apr 2002, 473 posts, RR: 0
Reply 24, posted (8 years 3 months 2 weeks 5 days ago) and read 3942 times:

Charliecossie, thanks!

and do you know where and what the 'forward access' is?



facebook.com/ddaclassicairlines
25 HAWK21M : Any Pic/Sketch. regds MEL
26 Charliecossie : There's a small electronics bay fwd of the nose gear bay. Not much up there.
Top Of Page
Forum Index

Reply To This Topic B777 Main Gear Steering Inop - WX?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
A340-600 Why No Body Gear Steering? posted Fri Nov 3 2006 18:16:18 by BALandorLivery
An-225 Main Gear Maintenance posted Fri Jul 14 2006 04:46:00 by 2H4
737 Main Gear Question posted Mon Jul 3 2006 23:28:50 by RMD11
Trailing-Link Main Gear Pivot Wear posted Thu Jun 15 2006 05:59:25 by 2H4
Push-back Using Main Gear?! posted Mon Apr 17 2006 21:58:05 by A342
MiG 31 Main Gear posted Wed Feb 8 2006 04:00:33 by Ar1300
Dash-8 Pilots - Landing Without A Main Gear posted Tue Nov 8 2005 15:55:33 by Vio
Main Gear On A380 posted Fri Oct 28 2005 18:53:34 by Logan22L
A380 Main Gear Doors posted Thu Jun 23 2005 09:27:08 by DH106
Experimental DC-10 Main Gear? posted Tue Mar 16 2004 00:12:45 by Musang

Sponsor Message:
Printer friendly format