Fleet commonality: minor difference, same manufacturer

[HungryBus]

Hey there,

I have a question about fleet commonality. Actually, multiple questions :/

Firstly, as far as I know, it is considered a good practice to collect fleet belonging to the same fleet group. In my case, I am trying to fill in the A319-100 that seemingly belongs to A318/A319/A320/A321 group. Does it mean that if I will mix, let's say, 319 and 320 and 321, these all will be in a same group and fleet maintenance costs will be as low as for the fleet consisting only from A319?

Also, a question about engines. Right now, I have engines from 2 manuifacturers: CFM and IAE, and within these 2, I have multiple variants (I was a little bit uncautious while negotiating a lease of the aircraft), like CFM56-5B7 and CFM56-5B5. Do these small differences in engine indexing (5B5 vs 5B7) affect the maintenance cost and will the more noticable difference (CFM vs IAE) will affect the cost?

Thank you in advance!

[groundbum2]

with your eye for detail you'll make  a fine AWS player! But the answers are yes no and no, The experienced player doesn't pay any attention at all to engine commonality, in the big scheme of things the sums are trifling.

And yes a fleet is exactly that, the members of the fleet (eg 737-800,737-900,737-900ER) are treated as if they are the same aircraft for the purposes of commonlity. So you can have lots of different aircraft types within that fleet and commonality will be the same,

Look at a big airline and you'll hopefully see they have 3 fleets but lots of aircraft types within those 3 fleets. Also bear in mind commonality penalties don't start until 450 aircraft approx. So all the big warnings you'll see about commonality will kill your airline only matter when you get huge. If you have say 20 aircraft and a healthy profit 4 fleets won't matter a bit. Likewise 5 fleets when you're larger. But you need to have a plan to be down to 3 fleets by the time you get 400+ aircraft for sure. Sometimes the used market is so short of aircraft you get to 4 or 5 fleets just to expand quickly.

Simon

[HungryBus]

Thanks a lot! So it means I can exapnd more quickly, since A319-100 with the same type of engine is way harder to find than couple of days before.

with your eye for detail you'll make  a fine AWS player!

As you can see, I accidentally leased an aircraft with different engine modification, so my eye for detail is not that good lol  Happens when you have millions of tabs open in browser

[gazzz0x2z]

(.../...)when you have millions of tabs open in browser

This is the way