A320 G+Y Hyd Failure

[Citation2]

G+Y summary says : For diversion , If Flaps jammed at zero: SELECT CLEAN CONFIGURATION Maintain speed close to VAPP (due to pitch trim unusable)

My question : how do you maintain speed close to Vapp if you have to select clean configuration?

[vilas]

This is a very good question. This is the change Airbus made from old QRH which said if flaps jammed at zero select clean configuration. Normal operating speeds(MAX SPEED= 250 KTS). The problem is the elevator is trimmed for Vapp but to retract slats(flaps are jammed) you will have to increase speed. When you moved the lever to position3 it was merely procedural as the slats have the same position for 2 and 3 so the lever can be put to 3. But from 2 to 1 and 1 to zero you will have to reverse the procedure VFE -5 and retract. Closest to Vapp will be VLS for flaps zero since VLS is always correct for the configuration.

[MD83FO]

whats the approximate speed delta between Vapp and clean Vls in this failure?

[vilas]

With dual hydraulic MAX speed for diversion is 250K because of doors remain open due to gravity extension. G+Y is different because elevator is trimmed for Vapp. For a weight of 60Tons normal Vls is 130+25=155 for G+Y. S speed is 185 that should be the Vls. So you could retract to flaps zero above that and maintain at least 195kts for safety. It will be tough because higher thrust will pitch up the nose. I think Airbus needs to give more details because if you retract early you can stall. Must try this in the SIM.

[Citation2]

Thanks for your input. Aircraft trimmed for Vapp , this could obviously lead to controllability issues if aircraft is accelerated to Vls conf 0, in direct law .I believe the safest way to divert , fuel permitting, would be to maintain current config , what do you think?

Fuel permitting : gear down + slats extended--> 180% +60%= 240% . Means trip fuel x3.4

[vilas]

Diversion with G+Y with gear down is only hypothetical. Why would you? The selection of the airfield for the first approach should have rule out any weather deterioration aspect. You won't be going far anyway. It will be a dire emergency. The aircraft control is difficult but not impossible.

[Jonty]

I agree with villas, if you're diverting in that situation, you're in a whole world of pain! Personally I would rather go off the end of the runway, than try it.