Title: Airbus Flight Control Logic: Landing Gear Extension and Trimming in Direct Law (A321)
Introduction:
As professional pilots operating Airbus aircraft, a comprehensive understanding of the Quick Reference Handbook (QRH) is paramount to ensuring the safety and efficiency of our flights. One crucial aspect covered in the PRO-ABN-ENG section, page 11/128 (A321), revolves around the flight control logic during landing gear extension. This article delves into the specifics of this procedure, emphasizing the importance of correct aircraft trimming for approach and the necessity of extending the landing gear only under certain conditions.
Background:
In the event of an abnormal situation leading to the extension of the landing gear, Airbus aircraft, including the A320 series, transition to Direct Law. Direct Law is a flight control mode that bypasses the usual protections offered by Normal Law, such as load factor protection and angle of attack protection. This transition occurs to maintain control authority in abnormal situations, allowing the pilot to have a more direct influence on the aircraft's control surfaces.
Direct Law and Landing Gear Extension:
The QRH procedure, as outlined in PRO-ABN-ENG P 11/128, specifically highlights that flight controls revert to Direct Law at the moment of landing gear extension. This shift in control logic necessitates a heightened awareness of the aircraft's behavior and a precise approach to managing control inputs.
Correct Aircraft Trimming:
To ensure a stable approach and smooth transition into Direct Law, it is crucial to observe two key conditions before extending the landing gear. Firstly, the aircraft should be configured to CONF 2, referring to the second stage of flap deployment. Secondly, the landing gear extension should occur at VAPP, which is the approach reference speed.
Configuring the aircraft to CONF 2 ensures that the aerodynamic configuration is suitable for the lower speeds associated with approach and landing. This configuration sets the stage for a more predictable response to control inputs during the transition to Direct Law.
Timing the landing gear extension at VAPP further refines the approach procedure. VAPP represents the reference speed for approach and landing, ensuring that the aircraft is at an appropriate airspeed for the extension of the landing gear. This meticulous timing minimizes potential disruptions in the approach profile and contributes to the overall stability of the aircraft.
Conclusion:
As professional pilots, understanding the intricacies of the QRH procedures, such as the one outlined in PRO-ABN-ENG P 11/128, is fundamental to our role in ensuring the safety and efficiency of Airbus operations. The logic behind the transition to Direct Law during landing gear extension emphasizes the need for a disciplined approach, with a specific emphasis on configuring the aircraft to CONF 2 and extending the landing gear at VAPP. Adhering to these guidelines enhances our ability to manage the aircraft effectively, even in abnormal situations, and contributes to the overall safety of our flights.