Hi,
I was wondering if it makes sense to have a standardized fleet, even within the maintainance categories in terms of administration cost.
For example
3x A320neo light
2x A320 light
vs
5x A320 light
Will more different airplanes increase me administration costs?
Thanks a lot!
Hello 
I see this is your first post - welcome !
The maintenance categories are set by the “Type Rating” for the aircraft.
In your example both aircraft are part of the A318/319/320/321 series and for maintenance purposes are the same aircraft. ie: you can fly any combination of them and they are “1” type.
You can fly any three “types” before you start to have a penalty to overall maintenance costs.
Cheers
No good reason to have standardized fleet as long as they are in the same family. Later on you will get bored of the used market and just order hundreds of the same plane (due to efficiency). For example, when I ran the Global Group there was no way of getting the amount of planes I needed on the used market. Therefore I settled on the most efficient plane in each class and got tons of them. I had over 1000 A320NEO and A321NEO taking care of the short and medium haul. Over 100 A350s taking care of the long haul and 100 A380s taking care of high density. I got to bored of diversity so I just operated my 3 large airlines them same, using the same planes and same model. I personally think commonality should be rewarded in AS as it is in real life.
That’s wrong. Type ratings affect the categories in which aircraft pilots are set in - they do not influence maintenance categories. Each aircraft has, on its information page, the maintenance category listed. Yes, the groupings are mostly similar (and for your example of the Airbus A320 correct), but there are differences.
For example, A330, A340 and A350 share the same type rating, but only A330 and A340 share the same maintenance category, while the A350 has its own. The Boeing 747 is split in three type ratings, but only one maintenance category, and so is the whole DC-9/MD-80/MD-90/717 family. The Boeing 757, 767 and 777 are even more complicated: While each famly has its own maintenance category, the type ratings are partially shared: 757/767-200/767-300 is the first, 767-400/777 is the other one.
wow - i have played this game on and off since 2012 and I did not know this. I thought that the type code was the determining factor. I had never in all my years noted the maintenance category code in the 2nd column at the bottom just above the “go to performance check”.
Thank you for this I wish we still had a wiki or place to put stuff like this so we could refer people to it. Even old guys like me don’t know how stuff works sometimes 
Thank you again for the correction !
After playing for years I think I have been doing this all wrong. I just want to make sure I am understanding everything above correctly.
For example I have 757, 767 and 777 in my fleet. I assumed the 757/767 crew type rating covered maintenance costs for fleet type. However, if I am understanding correctly for example a 757-200 with maintenance category of 6 and a 767-300ER with a maintenance category of 7 are driving up my costs because they are two separate categories? Although I have savings with one pilot type rating I am not gaining maintenance category commonality?
Thanks for the clarification in advance!
3 maintenance categories / aircraft types are ok. More than 3 makes the maintenance expensive. 15% surcharge per new type added (2 additional types means 30% more maintenance costs etc.).
Maintenance has nothing to do with pilot type ratings.
Martin stated in one of his past videos that maintenance was basically wrong. At the moment A B737-200 and a B737 Max are both category 1. I suspect the plan was to make the engine a much more important factor of the maintence cost. Just look at how many B787 operators also use A350s. The commonality is the Rolls Royce Trent engine. The 700 and 1000 are essentially the same design.
I wouldn’t call it wrong, but overly simplified.
True, engines can be the major cost contributor to maint. Usually I think of somewhere around 30-40%.
I agree that a 731 doesn’t have much in common with a 7M9, but where to start for a more realistic picture?
Maint could be carried out in-house or be contracted to a third party. In the latter case, the per engine cost might be higher, but an additional type of engine might factor in to a much lesser extend.
Particularly for engines, costs for maint depend on cycles and costs stongly rise the “older” the engine gets. Cycles aren’t counted at all.
I’d love to have a more complex simulation of maint, but this would be a much too complex task IMO. Right now we don’t even simulate shop visits for our airframes but have them on schedule all year long…
Would a change to a system that allows more maintenance categories, but also more categories maybe help? Lets say if 5 maintenance categories were allowed, but 737NG and 737MAX have a different category. I see the point, that the engine does not make the majority of spare parts and required training, but there a so many other differences between 737classic and 737MAX that different maintenance categories would make sense as the interieur and the cockpit have only very few things in common too. I would basically even go further and split A330 and A330neo or even A340-200 and A340-500 because there are huge differences too. It will be difficult to decide where to draw a line and of course like always there will be complaints. If you allow a fw categories more without cost penalties that can be compensated, if you dont that is an extra bonus for airlines with a straight forward fleet management.
To make it even more complicated a in house maintenance would make it even more interesting, but I guess that will never happen just like terminal customations like shops, restaurants… as long as PU is not done. And even afterwards most propably not the focus of Martin.
I don’t see where this would improve things in AS. IMO lots of work for little to no effect. And it wouldn’t make things more realistic.
The 330neo and 330 have a 95% commonality btw, that hardly would justify two categories. The neo’s difference is mainly around engines.
The exact opposite could be said about DC-10 vs. A300:
While they are completely different, the 10-30 and A300classics not only share the same engine but also use a common nacelle.
Consequently, a realistic approach would be to split maint costs into the three major contributors: