Proposed special considerations include one for the effects of flight-control systems, both in normal and failed conditions, on the structural capability and aeroelastic stability of the 787. Another requires that "suitable annunciation be provided to the flightcrew when a flight condition exists in which nearly full control surface deflection occurs".
Flight-control laws come in for attention from the FAA, which calls for special conditions governing the 787's flight-control system and its laws in the roll axis. The FAA appears to be concerned that "non-linearities or other effects on aileron actuation may be caused by electronic flight controls". Current Part 25 airworthiness laws cover control laws where aileron deflection during a design roll manoeuvre is proportional to control stick deflection, and are not updated to deal with the 787.
In particular, the FAA's special condition for the roll axis "requires an additional load condition at design manoeuvring speed, in which the cockpit roll control is returned to neutral following the initial roll input".
The proliferation of critical electrical and electronic systems throughout the 787 design mean the aircraft must pass rigorous high-intensity radiated fields protection tests. There is also a requirement for engine mounts and structures able to support maximum torques "without detrimental permanent deformation".
Source: Flight International
