A system failure may affect the flight characteristics, the braking capability, both of them or none of them.
Maybe you have to increase the Vapp because the failure by the delta Vref, thus increasing your ground speed and your landing distance.
Maybe you have a decreased braking capability, thus increasing your landing distance.
Maybe you have both of them or none of them.
If you have none of them you will not find the case in the tables (FPE-IFL-LD with failure) and delta Vref = 0, in a way that Vapp determination with or without failure is the same, you don't have to apply any landing distance correction and you use LD without failure tables.
In any case there is a V APPRoach CORrection which takes into account the ice accretion in the unprotected areas.
The ice accretion in the protected areas is taken into account in the "with failure" tables. For instance DC ESS SHED BUS failure will cause the wing A/I valve to close.
In the engine case if you push the Fire p/b the associated engine shutdown procedure will ask you to closed the cross bleed and the wing A/I OFF (to avoid asymmetrical anti ice) and in case of ice accretion the ice protection (secondary) failure must be reflected in the tables. But if you don't push the Fire p/b (undamaged engine) the shutdown procedure will request you, when in icing conditions, to open the cross bleed, one pack OFF and wing A/I ON, and the protected areas are then anti iced with no failure.
And where to look in for landing distance assessment as the table in QRH is not applicable during engine with no fire pushbutton pushed and ice accretion. Really need explanations with reference to appropriate documents.
if you cannot find the case in the "with failure" tables, use the without failure ones and the APPRoach CORrection for the VAPP determination to deal with the ice accretion in the non-protected areas.
Too long? Sorry. Vilas had the short answer
