Little Orange Maintenance Symbol

Hi, I’ve got quite a few fleet planes, and I know that the orange gear/spanner symbol that pops up on the aircraft’s card indicates that the plane requires maintenance at the end of its current contract.

However, sometimes my planes need maintenance even though the symbol hasn’t shown up, and sometimes the symbol is visible, but the plane doesn’t need maintenance.

Is there something I am missing here? Is there a better way to tell if a plane needs maintenance?

Thanks.

the MP remaining should be greater than or equal to the streak times per trip MP for example if you have
40MP LEFT for small check and you have contract which has 10 streak AND per trip MP cost is 4 or less than 4
then it can do the contract if its more then it requires maintenance