A330 L/G hydraulic isolation when V>280

[zonnair]

Hey there,

Please help me out.

The hydraulic supply for L/G operation is automatically isolated by closing a safety valve above 280kts. It is maintained closed until the L/G lever is moved down and the a/c speed is below 280kts.

Cruising at FL390, my speed turned out to be around 260kts. This is below the 280kts from the FCOM. If I select te lever down, I forfill the requirements to open the safety valve again. What will happen?

Is there a other safety feature installed, but not written about, or is it only a safety feature for unwanted gear extension at climb and descent, hence 280kts?

There is nowhere anything written that the max altitude of 21000' blocks the operation of the gear. So i disregard this.

Thanks in advanced,

ZNA

[Colin Oskopi]

If you are below 280 kts the only thing to stop you lowering the gear is not to move the handle.

[PappyJ]

The depressurization of the landing gear hydraulic suppy at speeds above 280 kts, is a design feature to eliminate the need for a gear lever "neutral" position.

I'm certain that there is, in fact, electronic logic to prevent activation of the LGCIU below 21000, but I'll be dambed if I can find a reference to it.

However, I've got drinkin' plans with our local Airbus Tech Service rep tonight, so I'll throw the question at him and let you know later.

Cheers

[zonnair]

Cool thanks pappyJ,

Drink one for me in the meanwhile :ok:.

[PappyJ]

Colin is correct.

I called my mate and asked (Couldn't stand not knowing).

After a check of the MX Manuals and Tech supplements for ADR's, etc, the findings are....

CAS (IAS for all intents and purposes) from ADR 1 or 3 below 280 kts, move the gear handle down, and you get....Noise!

The gear will go down irrespective of altitude.

(Above quoted from an Airbus Employed, A330 Technical Services Manager)

Which certainly explains why There is nowhere anything written that the max altitude of 21000' blocks the operation of the gear

I learned something new today.:8 Now it's time for those drinks....:ok:

Cheers

[NVpilot]

http://i63.photobucket.com/albums/h159/180MPH/A330.png

Will this help? :E

[zonnair]

hehe thanks pappyJ. enjoy the booze.