Creaking Sounds On 747-400 Nose Gear — Tech Ops Forum

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Creaking Sounds On 747-400 Nose Gear

744lover From Brazil, joined Nov 2000, 164 posts, RR: 0
Posted (6 years 1 month 3 weeks 5 days 10 hours ago) and read 3553 times:

Hello everybody

During the last month I've been working in Argentina for my company. I've flown on LH 747-400 (D-ABVS) from GRU to EZE on Feb 25th and on D-ABVT from EZE to GRU on March 22nd.

Since I was at the Business class I was near the nose gear and I could hear, when the captain steared it, a creaking noise comming from it. I could hear it on both planes that I've flown, so I think that it was not a isolated problem in one aircraft only.

BTW I recorded the backtrack procedure at RWY 35 at EZE and you can hear that creaking sound in it.

http://www.youtube.com/watch?v=5Y_a4gjhnmM

and here you can see the takeoff: http://www.youtube.com/watch?v=NKnB-gBgrW0

So, what is this creaking sound and why is it produced???

Thanks and best regards!
GHN

2 replies: All unread, jump to last

Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17
Reply 1, posted (6 years 1 month 3 weeks 5 days 1 hour ago) and read 3485 times:

The "creaking" noises are vibrations in the hydraulic system which drives the nosewheel steering. It is normal, not a problem. These kind of vibrations occur especially when a servo valve hits an endstop, like when the nosewheel is at maximum deflection. It can also be caused by a resonant frequency in the system, or a servo valve slightly out of adjustment.

I'm talking very generally. A hydraulics expert would be able to provide much better information.

The glass isn't half empty, or half full, it's twice as big as it needs to be.

Nonfirm From United States of America, joined Sep 2005, 434 posts, RR: 0
Reply 2, posted (6 years 1 month 3 weeks 4 days 19 hours ago) and read 3433 times:

I am not sure about the 747 but in the 737 we get a moaning or popping noise from the nose gear and it comes from the trunnion bearings.It is deferable item per Boeing for up to 25 flt hrs (for the airline i work for) after you check the bearings.Then to repair the noise you need to jack the nose spray the bearings with dry lube and swing the gear. airplane