LAF(LOAD ALLEVIATION FUNCTION) in Aircraft

1) Generally spoiler 4&5 of each wings are fully deployed in turbulent weather or in gust conditions under LAF. This behavior seems to occur when the G load demand by the pilot (input from control stick) and the current G load of the aircraft differs from 0.3G. 

However, LAF is inhibited when FLAP config is different from 0, Speed below 200 KIAS or above Vmo+10, alternate or direct law. This means LAF orders will only be available in NORMAL LAW or clean configuration.

2)The LAF permits to alleviate the wing structure loads. The function is achieved through the upward deflection of :

   a) the two ailerons only or,

   b) the two ailerons associated with the Spoilers 4&5.

             The LAF has two sub functions:

​- A sub-function activated in case of stable manoeuver. (aileron deflection only).

- A sub-function activated in case of gust detection. (aileron and spoiler 4&5 deflections).

In case of continuous turbulence, the two LAF sub-functions can be activated independently( the highest alleviation is taken into account).

It has a independent accumulator/ actuator installed for the actuation orders in compliance from EFCS and ACCELEROMETER (for G load)  located in inboard of aileron of each wing. It was there in older versions of A320 and again reintroduced in sharklets. In sharklets, accumulator has been replaced by LAF functions in flight control computers.