Yes. Sounds about right.
~ Fleet commonality works roughly
like a tax bracket. As you move up, down, add or subtract, your costs increase/decrease.
So you start w/ 11 small
aicraft as your only fleet. Excellent fleet common!!
But now, you add a DC-9. So one, you add another fleet type. That in itself adds 30k (for example). Ok, well you added a "medium
" class aircraft. So because its not in the same group, (small class, medium class, large class ect) that adds an extra 15k for not having the same class
But wait, wait no.. you added another fleet type. So + 30k again. Well... its another medium
class so that's 15k extra as well. Oh wait.. you already have 1 medium class of aircraft.. thats not good fleet common... thats going to be an extra 10k for having two medium class of aircraft.
So walaa! 100k more a month in fleet common costs on your Otters for adding two, different fleet types and classes to your fleet. Taadaa!
Kinda make sense now?
Now, if your costs double.. which aircraft will feel the most pain by doubling fleet common costs.. an Otter or 747?
So in your case, doubling your expenses have a more profound effect then someone who flies bigger aircraft. Thus, its same fleet common break down for everyone, just some people feel it more then others
If you plan to operate small aircraft, stick with small aircraft. It helps, cost wise were your $$$ doesnt go as far as running a big airline.
Hope this helps