Line maintenance is still going to be a cost for most airlines. The few MROs I know make 25-40% on line services. That is what "weekly" maintenance is in this game, or at least how I interpret it. Every time the plane lands, you have to pay the mechanics to inspect the plane, check the log books, change tires, rotate the data disks, advise the pilot during the preflight, pushback/engine starts, etc. Also, since ABCD checks are not going to be noob friendly, especially with simplistic used aircraft market, I am also gonna assume that the weekly maintenance is also including the amortization of the checks.
Let's go back to the same manufacturer thing.
I am not disputing that a maintenance with a single manufacturer group is going to make it cheaper, I am saying the amount is negligible. The saving you get is from bulk acquisition of parts. Eg. 100 Airbus parts instead of 50 Boeing and 50 Airbus, assuming your fleet is split 50/50. Maybe a bit from loyalty if you have special maintenance that can only be done by the manufacturer like AOG (usually stuff the pressure bulkhead damage or tail strikes and the like) or transitions.
Lets say a 727 and a 777-200. You are going to need another engineer, another set of tools, another set of training, another set of parts. Maybe the same avionics guy.
Now lets look at a 737-800 and A320. You are going to need another engineer, another set of tools, another set of training, another set of parts. A different avionics guy. See how it is similar to above? You might have to spend a bit more in comparison, but not a lot.
Consider scenario with A319 and A320. You can get the same engineer to sign off, tooling will be the same, only 1 set of training since Airbus certifies in families, and shared pool of parts. This is when you are going to save significant amounts of money.
Another reason why same type does save is parts swapping. Like engine swaps and the like. But you are not going swap an engine between a 787 and a 737, even though both are Boeing.
And with learning aspect, maybe for the mechanic to learn quicker or something, but from a legal, and from a company standpoint, each type family is completely separate, and they all require separate tests, ratings, and training courses. When my brother did his type rating for the 777 it took him ~1 month, total, including practical and courses and the cert. When he did the 737, about the same. 3.5 weeks for the A320.
Your maintenance company isn't going to charge less if you own an all Boeing or an all Airbus fleet. With large maintenance companies like ST Aero or HAECO, they are probably not going to care for type or manufacture. A C check for a 777 is $XX and a 737 is $YY. Maybe a bulk discount, but that is committing to amount of checks and is not dependent on manufacturer. As with all maintenance related activities in every industry, the largest cost is going to be labour.
Let's go back to the same manufacturer thing.
I am not disputing that a maintenance with a single manufacturer group is going to make it cheaper, I am saying the amount is negligible. The saving you get is from bulk acquisition of parts. Eg. 100 Airbus parts instead of 50 Boeing and 50 Airbus, assuming your fleet is split 50/50. Maybe a bit from loyalty if you have special maintenance that can only be done by the manufacturer like AOG (usually stuff the pressure bulkhead damage or tail strikes and the like) or transitions.
Lets say a 727 and a 777-200. You are going to need another engineer, another set of tools, another set of training, another set of parts. Maybe the same avionics guy.
Now lets look at a 737-800 and A320. You are going to need another engineer, another set of tools, another set of training, another set of parts. A different avionics guy. See how it is similar to above? You might have to spend a bit more in comparison, but not a lot.
Consider scenario with A319 and A320. You can get the same engineer to sign off, tooling will be the same, only 1 set of training since Airbus certifies in families, and shared pool of parts. This is when you are going to save significant amounts of money.
Another reason why same type does save is parts swapping. Like engine swaps and the like. But you are not going swap an engine between a 787 and a 737, even though both are Boeing.
And with learning aspect, maybe for the mechanic to learn quicker or something, but from a legal, and from a company standpoint, each type family is completely separate, and they all require separate tests, ratings, and training courses. When my brother did his type rating for the 777 it took him ~1 month, total, including practical and courses and the cert. When he did the 737, about the same. 3.5 weeks for the A320.
Your maintenance company isn't going to charge less if you own an all Boeing or an all Airbus fleet. With large maintenance companies like ST Aero or HAECO, they are probably not going to care for type or manufacture. A C check for a 777 is $XX and a 737 is $YY. Maybe a bulk discount, but that is committing to amount of checks and is not dependent on manufacturer. As with all maintenance related activities in every industry, the largest cost is going to be labour.