744lover From United States of America, joined Nov 2000, 209 posts, RR: 0 Posted (8 years 10 months 2 weeks 6 days 12 hours ago) and read 6209 times:
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.
Jetlagged From United Kingdom, joined Jan 2005, 2612 posts, RR: 25
Reply 1, posted (8 years 10 months 2 weeks 6 days 3 hours ago) and read 6141 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 (8 years 10 months 2 weeks 5 days 20 hours ago) and read 6089 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.