A400M Handling Qualities and PIO Resistance Analytical Criteria and Operational Manoeuvres with Respect to the Specific Problems of a Large Military Transport Aircraft with Full Authority Fly-by-Wire Flight Controls

Abstract

The A400M is the new military transport aircraft procured by the German government to replace the aging C-160(Transall).As a modern military transport aircraft with full authority fly-by-wire flight controls the A400M has to fulfil a great variety of highly demanding mission requirements under challenging conditions, especially during wartime operations.To ensure the successful completion of tasks which make up the design the aircraft and to keep the pilots' workload at an acceptable level, very good handling qualities and excellent controllability of the aircraft need to be ensured for the complete operational envelope. The introduction of fly-by-wire flight controls has solved many problems and has led to a new quality of mission variety; however, new handling quality-related problems have been introduced as well.The only aircraft currently in operational use which is comparable to the A400M from a flight control system point of view is the C-17; and its developmental and operational history has shown that designing for good handling qualities (HQ) and pilot-in-the-loop-oscillation (PIO) resistance is still a goal which is hart to achieve. After PIO problems that occurred during developmental flight tests were cured, the aircraft was believed to be PIO resistant and no incident was reported for several years. However, with the deployment to Iraq (operation enduring freedom, OEF) in 2001, new PIO problems sufaced, mainly triggered by the raised increased pilot gains in the during tight manoeuvring demanding in a hostile environment occurred and led to several wing scrapes and hard landings.