IFALPA - Klart angrep på Airbus` filosofi

13POS02 31 August 2012

Electronic Flight Control systems

Handling qualities

In order to preserve pilot feel of electronic flight control systems, the minimum acceptable criteria are those specified in SAE International ARP 4104, which provides design objectives for civil transport aeroplane handling qualities in the following sections:

1) Longitudinal flying qualities, section 2.3;

2) Lateral directional flying qualities, section 2.4;
3) Miscellaneous flying qualities, section 2.5;
4) Characteristics of the flight control system, section 2.8

 

In addition, flight control systems which serve reduced statically stable aircraft (by their aerodynamic characteristics), such as the fly-by-wire system, should provide a back-up system, totally independent of the primary system.

Note: It is acceptable that the flight envelope becomes restricted when using the back-up system.

 

Dual control capability

The system design should ensure:

a) that all inputs from one side are reflected in equivalent simultaneous movement of the other side; and
b) that all inputs into the control system from the auto-pilot are reflected in equivalent simultaneous movements of both
control devices.

Thrust/power control

Where an automatic thrust/power control device is used the system design should ensure that all the device’s outputs aimed at changing the thrust/power level are reflected in equivalent simultaneous movement of the thrust/power levers. Throttle movement (reflecting power modulation) is essential to enable the pilot to monitor effectively the change in power levels achieved by the automatic full authority digital engine control (FADEC) device.

Note: Monitoring of power levels by observation of engine instruments is not adequate due to the fact that the engine instrument panel does not lie in the normal scan pattern of the pilot.

Stall protection system

Where a stall protection system is fitted to an aircraft, the pilot should be informed by an appropriate means when the system is limiting the angle of attack.

The target angle of attack and the actual angle of attack should be displayed so that the pilot can monitor any system discrepancy and correct manually to provide the optimum angle of attack in the event of a discrepancy.
Stall protection should be available at all heights, right down to the flare on landing.
The system should be set to maintain conventional margins to the stall and should not be used as a device to allow reduced margins in all flight phases.