A320 landing gear usual noise on extension

[IFLY_INDIGO]

I wonder what is the reason for that common initial 'bang' noise LG makes when we extend it in A320? is it the noise of uplock release?

[J.L.Seagull]

It's the doors.

If you have time on ground, and situation permitting, ask a technician to open and close the NLG doors for you. It sounds like a sharp knock.

[nitpicker330]

Not on the A330, the main gear first makes a loud crack/bang as the uplocks release.

[spannersatcx]

A330

RETRACTION
Doors Open
Gear Locked Up
Doors Closed
EXTENSION
Doors Open
Gear Locked Down
Doors Closed

Doors are unlocked and opened before anything happens with the gear, this is done through proximity sensors and door selector valve inputs to the LGCIU's.

[nitpicker330]

Mmmmmmm,

Well it's either the door uplocks or the gear uplocks making the loud crack/thump that makes you feel like the Aircraft just jumped up!!

Either way its quite loud....

[rudderrudderrat]

Hi Ifly_indigo,

I wonder what is the reason for that common initial 'bang' noise LG makes when we extend it

On the L1011, the gear made the same loud "bang" when selecting down. We had "Up", "Off" and "Down" selector positions, and Off was used to unload the hydraulic pressure once the gear was locked up.
It became common practice to initially select "Up" then "Down" to remove that "bang" noise completely. Unfortunately the number of hydraulic pressure cycles on the main gear doubled per sector and we had premature failures of the main hydraulic ram cylinders.

Since there was no "bang" noise when selecting Up first - I guess the gear was not resting on the Up Locks, so when selecting down it allowed the up locks to open before the weight of the gear rested on them.