A330/A340 2.60.9 Flight Controls
FCTM REV 1 (6 JUN 05)
When high speed protection is triggered, the autopilot disconnects, the pitch trim is frozen, the spiral static stability is reduced from 33° to 0° of bank and the limit bank angle is reduced from 67° to 45°. If high speed protection is active with the aircraft established in a turn, when the sidestick is released the aircraft will roll wings level. This increased spiral stability reduces the risk of a spiral dive.
2.60.10
A330/A340 General Information REV 1 (6 JUN 05)
FCTM Flight Controls
Bank.Angle.Protection
On commercial aircraft, 30° bank angle is normally not to be exceeded. A bank angle of 67° in level flight corresponds to the aircraft limit of 2.5 g. Therefore, 67° has been established as the bank angle limit. Approaching this limit, the roll rate is progressively reduced to avoid over-banking.
This 67° bank angle limit is reduced to 45° in case of high speed protection.
ALTERNATE.LAW
In some cases of double failure, e.g. double hydraulic failure, the integrity and redundancy of the computers and other required systems are not sufficient to achieve normal law with its protections. In this case, Alternate Law is triggered. VLS remains, but á prot and á max disappear, replaced by a single black and red strip, the top of which is the stall warning speed VSW. Unlike VLS which is stable, VSW is g sensitive so as to indicate margin above stall during turns. The autopilot may be available depending on the cause and type of failure(s). During landing, alternate law reverts to direct law at 100 ft RA.
If the aircraft is operated outside the normal flight envelope, the pilot must take appropriate corrective action to avoid losing control and/or to avoid high speed excursions, since the normal law protection features may not be available.
Handling.Characteristics
In pitch, handling remains similar to normal law.
In roll, depending on the failure level, control is either normal (ALTN 1) or direct (ALTN 2). In roll direct, the aircraft appears to be very sensitive and bank stability is no longer active.
Protections
In Alternate Law the protections change as follows:
.
High angle of attack protections are replaced by stall warning at 1.03 VS1g
.
The load factor protection is maintained
.
The pitch attitude protection is lost
.
The high speed protection is replaced by overspeed warning
.
The bank angle protection is maintained if roll is normal (ALTN 1) but lost in roll direct (ALTN 2)
A330/A340 2.60.11 Flight Controls
FCTM REV 1 (6 JUN 05)
DIRECT.LAW
In most cases of triple failure, e.g. triple ADR failure, direct law is triggered. Autopilot and auto-trim are not available.
Handling.Characteristics
The handling characteristics are similar to a conventional aircraft. Any tendency to roll stick free can be corrected by conventional use of the rudder. Rudder trim can be used in the conventional way, but note that the sideslip index may be slightly displaced from the centre once the rudder forces have been trimmed out. Rapid speedbrake application and large thrust changes will result in significant pitching moments, i.e. nose-up with thrust increase and nose down with thrust reduction.
In pitch, elevator deflection is proportional to sidestick deflection. It is important to note that the controls are very powerful. Consequently, use small inputs when at high speed. As there is no auto-trim, use manual trim making small inputs on the trim wheel.
In roll, aileron and spoiler deflection is proportional to sidestick deflection. Direct law works with the yaw damper to provide a minimal turn coordination.
Protections
No protections are available but overspeed and stall aural warnings remain available.
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