Oct 25

Airspeed unreliable and flap load relief

You have airspeed unreliable, you perform the approach to land, but due to false high speed indication it is impossible to extend flaps (Flap load relief) beyond F5 (SFP) or 25 (Non SFP) what to do in that situation? Is it advisable to use alternate flaps to extend flaps up to landing flaps (30/40)?

Hi Matt,

We were discussing this recently on our Facebook page. It has happened to one of the crews, where unreliable airspeed on the captain's side triggered flap load relief. The flap load relief retracts the flaps only one setting up from the selected flap setting. That means that you can set flaps 30 even with flap load relief active.

Note: According to one of the engineers on the FB forum the flap load relief should not activate with IAS DISAGREE. He said that ADIRU should send a discreet to FSEU to inhibit flap load relief. I wasn't able to verify this as he hasn't provided any reference and there is no mention about this in the AMMs.