Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Landing Gear Knocking Sound In Airbuses  
User currently offlineOD-BWH From , joined Dec 1969, posts, RR:
Posted (10 years 12 months 4 days 4 hours ago) and read 11984 times:

I've recently flown onboard the A330-200 and A321, and in both aircraft, a loud knocking noise was heard everytime the landing gears are deployed before landing. I've heard that many times. What is this noise from?

I've flown the 777 also, and i'm sure there's no such noise...

OD-BWH


12 replies: All unread, jump to last
 
User currently offlineLimaFoxTango From , joined Dec 1969, posts, RR:
Reply 1, posted (10 years 12 months 4 days 2 hours ago) and read 11916 times:

im guessing that noise you hear is when they locked into place when fully extended. you will tend to hear this knock on any aircraft that has retractable gears. you will also hear that knock as the retact as well. i guess some are louder than others. i guessing someone here will elaborate on the technical side of it.

User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 2, posted (10 years 12 months 4 days 2 hours ago) and read 11902 times:

Well, I've noticed this in every plane I've flown and I made this conclusion:

The smaller the airplane, the stronger the knock.

 Smile/happy/getting dizzy


User currently offlineLimaFoxTango From , joined Dec 1969, posts, RR:
Reply 3, posted (10 years 12 months 4 days 2 hours ago) and read 11900 times:


Well, I've noticed this in every plane I've flown and I made this conclusion:

The smaller the airplane, the stronger the knock.


probably because the smaller the plane, the closer you are to the landing gear.


User currently offlineBuckfifty From , joined Dec 1969, posts, RR:
Reply 4, posted (10 years 12 months 3 days 22 hours ago) and read 11842 times:

That's just the noise of the oleos hitting the stops as the gear is fully extended.

User currently offlineMYT332 From , joined Dec 1969, posts, RR:
Reply 5, posted (10 years 12 months 3 days 10 hours ago) and read 11768 times:

When your sitting right above the gear wells, it sounds like the dam things breaking off!

Very loud on the A332, scared me sh*tless at one point!


User currently offlineA/c train From , joined Dec 1969, posts, RR:
Reply 6, posted (10 years 12 months 3 days 5 hours ago) and read 11739 times:

Buckfifty, can you elaborate on that, it doesnt sound right or ''healthy'' to me. Could be wrong though

User currently offlineAir2gxs From , joined Dec 1969, posts, RR:
Reply 7, posted (10 years 12 months 3 days 3 hours ago) and read 11719 times:

The oleos are already at full extension when the enter the gear well. Thus, when the gear is extended there should be no noise from shock strut (oleo) extension. There is a small variety of things you may be hearing. I'm no Airbus expert (worked Boeings and Douglas most of my career), but I suspect you're hearing the doors closing after the gear extension cycle is complete. You may also be hearing the gear locking mechanism going over-center, but I doubt it.

User currently offlineWirelock From , joined Dec 1969, posts, RR:
Reply 8, posted (7 years 9 months 3 weeks 3 days 17 hours ago) and read 11331 times:

Oleos are pressurized so the are always at full extend unless with aircraft weight on them. done a few functional tests of the A320 LDG in my time. from looking at this from the outside the things that make noise are the sound of the over centre locks engaging, doors closing. sometimes the PTU will kick in so maybe you are hearing this

User currently offlineHAWK21M From , joined Dec 1969, posts, RR:
Reply 9, posted (7 years 9 months 3 weeks 3 days 7 hours ago) and read 11252 times:

From your description it looks most likely like the Uplocks releasing mechanical sound.
regds
MEL


User currently offlineTdscanuck From , joined Dec 1969, posts, RR:
Reply 10, posted (7 years 9 months 3 weeks 2 days 21 hours ago) and read 11184 times:

Quoting Air2gxs (Reply 7):
The oleos are already at full extension when the enter the gear well.



Quoting Air2gxs (Reply 7):
Oleos are pressurized so the are always at full extend unless with aircraft weight on them.

There are a (very) few airliners that can retract the oleos prior to stowage for space reasons...I seem to remember the A340 center post does this.

Tom.


User currently offlineJetMech From , joined Dec 1969, posts, RR:
Reply 11, posted (7 years 9 months 3 weeks 2 days 16 hours ago) and read 11161 times:

Quoting Air2gxs (Reply 7):
The oleos are already at full extension when the enter the gear well. Thus, when the gear is extended there should be no noise from shock strut (oleo) extension.



Quoting Tdscanuck (Reply 10):
There are a (very) few airliners that can retract the oleos prior to stowage for space reasons

The A330 / A340 has a gear shortening mechanism on the wing gears. The external crank mechanism for this can be seen just ahead of the rear wing landing gear trunnion point in this photo.

http://i94.photobucket.com/albums/l118/Jet-Mech/IMG_0824.jpg

What you both say is true however. The pressurised nitrogen and landing gear fluid are housed in a "shock cartridge" that is free to slide up and down inside the main landing gear casting. Thus, when the A330 / A340 wing landing gear retracts, the crank pulls the sliding shock cartridge into the main landing gear casting via a mechanical linkage internal to the landing gear casting. The sliding shock catridge in turn pulls the inner cylinder, bogie beam and hence wheel and brake assemblies towards the main gear casting as well. The end effect is a physical shortening of the wing landing gear.

The internal mechanism is so arranged that upon extension of the wing gear, an overcentre lock is formed inside and against the wing gear main casting upon full lengthening of the gear. This overcentre mechanism locks the sliding shock cartridge inside the main gear casting, and allows it to take the landing shock as well as the weight of the aircraft.

Quoting Tdscanuck (Reply 10):
I seem to remember the A340 center post does this.

I not too sure about this one. I am quite cetrain that the A342 / A343 centre post does not shorten. I am reasonably sure that this is the same case with the A345 / A346 centre gear as well.



One point of interest seems to be that all Airbus oleos are of the double chamber design, which supposedly gives smoother absorption of landing shocks.

Regards, JetMech


User currently offlineReidYYZ From , joined Dec 1969, posts, RR:
Reply 12, posted (7 years 9 months 3 weeks 1 day 19 hours ago) and read 11070 times:

Quoting JetMech (Reply 11):
centre post does not shorten

You are corrrect. As you know, but I will explain for those who don't, the wing gear for both A330/340 shorten because it is the same gear for both aircraft. It has to shorten due to the lost space where the ctr gear stows on a A340 but be long enough for ground clearance for A330 larger engines. Jean Dixon predicts: But the A330 has no center gear? Again, correct, but the big empty space is still there.


Top Of Page
Forum Index

Reply To This Topic Landing Gear Knocking Sound In Airbuses
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...
Wierd Creaking Sound On EMB-145 Landing Gear posted Wed Jul 7 2004 23:54:56 by Cancidas
Landing Gear Handle In The 737 posted Thu Apr 8 2004 23:06:50 by Yousef727
Landing Gear Failure posted Sun Sep 10 2006 16:12:48 by A320ajm
A380 Main Landing Gear posted Mon Jul 17 2006 05:30:09 by WingedMigrator
MD-80 Landing Gear posted Thu Jun 1 2006 18:52:52 by B737200
Aircraft Landing Gear Wheel Allignment posted Thu May 11 2006 14:07:40 by IsuA380B777
Landing Gear Deployment posted Tue May 2 2006 06:42:33 by Slovacek747
Why The "wheel" On Landing Gear Levers? posted Fri Mar 3 2006 11:52:41 by Slinker
737 Main Landing Gear posted Wed Feb 1 2006 00:26:16 by Letsgetwet
Why Is The Gear Called Main Landing Gear? posted Tue Dec 13 2005 03:02:52 by Airfoilsguy
Wierd Creaking Sound On EMB-145 Landing Gear posted Wed Jul 7 2004 23:54:56 by Cancidas
Landing Gear Handle In The 737 posted Thu Apr 8 2004 23:06:50 by Yousef727
Great Video of 747 landing gear. posted Tue Apr 17 2012 12:13:06 by famfflores

Sponsor Message:
Printer friendly format