I am sure there is a bug. The monthly aircraft mantainance number shown in the Airline Finance report, is the year number and no the monthly number.
For example in Aircraft Mantainance in the Airline report i have USD$10 Million of Montly Cost
However the Montly expenses shown in the aircraft reports states a montly cost less than USD$1 million.
So this way is difficult to keep profit.
Please check it, thanks