How does the LIP package which is standard on the A320NEO enable to approach at a slower speed? Could someone kindly explain as to how the lift improvement package on the A320NEO enable it to approach at a slower speed compared to the IAE CEO. I have the list of the modifications which is done but it doesn’t explain how it helps.

They are:


Slats (de icing slay/track shutter modifications and stiffened slat/track seals)
Slat 1 enlarged horn
Adding an outboard nacelle strake
Fuselage wing fairing root fillet aerodynamic improvement 
Wind shroud close to flap 1 and 2 junction 
Introduce extended trailing edges on spoilers 1 and 2 and on fixed wing box trailing edge between spoilers 1 and 2.


These modifications mainly allow the aircraft to approach up to 5 knots slower than our CEOs. But how exactly do the modifications work in reducing the approach speed?
On first impressions, all of those (except the nacelle strake and the fillet) seem to modify the high lift system (slats/flaps), presumably to optimise air flow in the gaps between slat and main wing or main wing and flaps. This is probably done to increase the maximum attainable angle of attack or lift coefficient, which will reduce stall speed and thus allow a lower approach speed.

The nacelle strakes normally are used to optimise flow around the engine nacelle at high angles of attack, either to prevent premature wing stall around the nacelle or to at least improve aircraft handling qualities by preventing localised flow separation at the nacelle. Adding another strake on the other side will, I imagine, again allow a slightly higher angle of attack to be sustained and thus will lower the permitted approach speed.

The wing body fairing modification most probably, too, will allow a more optimal local air flow.

All of this is my speculation based on the list of changes in the question; I don’t have additional knowledge on this particular aircraft performance package.