The Primary computers (PRIMs) have different computation laws, divided into three levels.
– Normal
– Alternate
– Direct.
These levels are in relation to the availability and reliability of the A/C attitude and air data sensors.
The control laws give protection to keep the airplane attitude in the flight envelope with a security margin.
The normal control law has the highest level of protections while the alternate law has less protections and the direct law has no protection.
The direct control law deflects the surfaces directly proportional to the side-stick or rudder pedals deflection.
On ground, only the direct control laws are available.
The normal control laws supply some of the protections that follow:
– Load factor protection
– Angle Of Attack (AOA) protection
– High speed protection
– Bank angle protection
– Maximum rudder deflection protection.
Author – Mohamed Freihat
(C130/L100 , A&C approved consultant)