As your question is for a university, they will want to see a logical argument presented so here arte some points I believe you can expand on. The following are just ideas you toss around in your report. No costs listed as its impossible to quote exactly as they vary due to local conditions.
You need to consider where the aircraft area based and where they are flying to and when there next major checks are due and are the aircraft bought or leased. Things to think about:
(1) Aircraft based in Europe has access to many third party maintenance facilities dealing with up to B747 size within close proximity; so many checks can be outsourced, with facilities stretching from Madrid to Hamburg, to Shannon etc. If aircraft is based in say Africa and its routes are only within Africa (or the middle of the Pacific), it does not make sense to ferry an empty B747 aircraft to say Europe or South Africa for an A check, but if the routing involves flying to Johannesburg, you can plan your checks to be done by a firm based there.
(2) A leased aircraft usually has a clause specifying what check type to be performed prior to return to leasee (regardless if it is due or not)
(3) Is the aircraft being bought by the operator (using its or the banks money) then ask the question is a major mod, inspection due soon? Aircraft can be bought cheap but a mojor mod may be due. If you do the mod inhouse (assuming you have the expertise) doing it may cover the cost of tooling, stand etc that can be used to do other checks in house, as opposed to getting a third party facility to do it.
With the fleet you have quoted, out sourcing makes the most sense. Think of the following.
(1) There are no economies of scale with three different types of aircraft, particularly of the different sizes you quote. Notice how the low costs carriers, such as Ryanair, keep a standard aircraft.
(2) Local regulations may state that all maintenance has to be carried out under cover. Building a hanger of B747 size is prohibitive for three aircraft fleet.
(3) Local staff availability. You may not have local B767 experienced persons, so you have to take into account training and learning curve costs
(4) How does local law effect labour productivity (overtime limitations, paid leave etc)
(5) Tooling and access/stand costs
(6) Spares costs (you will be surprised at the cost of keeping spares and three different aircraft increase you costs for rotable spares. Some consumables are calendar life limited)
(7) Manuals and their revision service and engineering services costs.
If outsourcing maintenance, there are still costs involved,
(1) keep the maintenance planning inhouse so you know what’s coming due and the third party maintenance facility is not dictating the check requirements. It is not in the third party maintenance facility interest to help you phase your checks over a longer period of time (it cuts down the money they earn). Maybe that AD they insist on doing now is not due till next year and you can ask to do it when the galley is coming out for the corrosion inspection due next. You can specify exactly what you need done, therefore keeping your costs down
(2) You still need experienced mechanics on your staff even if the maintenance is outsourced, but they are there to do line maintenance at home base. Ensure they rep the maintenance checks.
(3) You need a good contract with the maintenance provider, so you need the lawyers. Insert clauses for late delivery penalties etc. (but keep money aside in case you do have to lease an aircraft while you aircraft is still stuck in the hanger, you got a small fleet) You will not get the penalty money immediately (everybody will be busy blaming everybody else) but your good rep on the check should be able to tell if the check running late, so you fore warned.
But remember if you pay peanuts you get monkeys. Sometimes the cheap outsourced maintenance can prove more expensive than if you did it inhouse, if the aircraft come back with more snags than they went in with.
There are many variables to consider and I have just scratched the surface. Accountants like the simple answer, on the ground its not so simple (anyway get a good ex-accountant from Anderson or Worldcom and he can write off all the costs for setting up a maintenance facility and the maintenance costs somewhere, ha)