UA A320 at DEN: "Total Hydraulic Failure"?

[ableone]

wrong rookie. Is possible to fly it for extended periods of time or can it be landed? Yes. But Airbus intended mechanical backup to be a temp. situation. It is almost impossible to fly an instrument approach. You better have a long and wide rwy and vfr.


M

As usual, wrong again.

Though the airplane can be flown and landed just fine in the emergency electrical configuration it is this configuration that airbus intended to be a temporary flight condition allowing the crew time to restore at least partial main power.

Mechanical backup was not viewed as a temporary condition but one that would result from the complete failure of all electrical systems.

It was required under part 25 that there be a way to control and land the airplane sans electricity.

Try again.

 

[MCDU]

So, if you can not land in mechanical backup, do you fail your checkride? Answer. No
Airbus does not expect you to be able to land in mech. backup. There are too many redundant systems. Just a battery is enough for direct law. Mech backup is designed to keep the plane flying til you establish lost systems.

M

 

[MCDU]

In case of a complete loss of electrical flight control signals, the aircraft can be temporarilycontrolled by mechanical mode.

• Pitch control is achieved through the horizontal stabilizer by using the manual trim wheel.
• Lateral control is accomplished using the rudder pedals.
• Both controls require hydraulic power.
• A red MAN PITCH TRIM ONLY warning appears on the PFD.

 

[ableone]

So, if you can not land in mechanical backup, do you fail your checkride? Answer. No
Airbus does not expect you to be able to land in mech. backup. There are too many redundant systems. Just a battery is enough for direct law. Mech backup is designed to keep the plane flying til you establish lost systems.

M

If the manufacturer could not demonstrate the aircraft could safely land in mechanical backup it would not have been certifiable.

Airbus never expects one of their airplanes to be landed with anything less then partial main power. Emergency electrical is there to provide the crew time to restore power.

The only time airbus envisions an aircraft in mechanical backup is after a complete and unrecoverable electrical failure which includes ships batteries.

Should the aircraft degrade to this condition it is not thought that there would be an electrical recovery mode available.

Your characterization of this as a temporary flight condition is incorrect. Mechanical backup is viewed as a theoretical last resort.

Try again.

 

[MCDU]

Mechanical backup is viewed as a theoretical last resort

Kind of like Nukes.

I agree with that statement.

M

 

[Dogwood]

As usual, wrong again.

Though the airplane can be flown and landed just fine in the emergency electrical configuration it is this configuration that airbus intended to be a temporary flight condition allowing the crew time to restore at least partial main power.

Mechanical backup was not viewed as a temporary condition but one that would result from the complete failure of all electrical systems.

It was required under part 25 that there be a way to control and land the airplane sans electricity.

Try again.

I believe I agree with the statement that without Hyd you are an uncontrolled lawn dart.

Mech Back up is for a complete lack of Flight Control Computers, not for a complete loss of Hyd.

With no Hyd, how do you move the control surfaces? Answer is ... you can't.

 

[MCDU]

Dogwood is correct.

M

 

[MCDU]

I would give anyone a million bucks if you land an airbus in mechanical law in IFR conditions.

M

 

[ableone]

MCDU you have read but not understood the manuals.

If an instructor wishes to degrade the sim to mechanical control he/she disables all the flight control computers which then places the airplane in mechanical and generates the "man pitch trim only" message.

However, the complete loss of electricity, (the primary reason certification authorities required mechanical backup) will not generate any of the messages you have cited as the screens they are displayed upon will be unpowered.

You keep stating that mechanical backup is for temporary failures to allow the crew time to restore power. Once generators and batteries are lost there is no recovery mode available.

Following the loss of the generators and batteries, all the switches on the overhead panel will be unpowered and useless. There is no longer any way to try and reset and recover power.

Once all electricity is lost and the airplane is in mechanical backup there is no going back.

 

[Dogwood]

I must have been hallucinating when I watched the test pilots land the airplane in mechanical backup as part of its original certification program.

Further I guess I was dreaming when I landed the airplane with the trim wheel and pedals as part of my original training.

Further I must have also hallucinated the mechanical backup landings that my sim partner and I performed when I returned to the airplane several years ago.

Are you saying you did this with a complete Hyd failure? Or Elect Failure?? Big difference.

If you did this with a Total Hyd Failure, then I need to back to school, but I doubt that you did.

The purpose of Mech Backup is to give you time to reset the flight control computers. That's about it.