RunTheModel - Aircraft Maintenance Checks - Transportation & Logistics

Aircraft Maintenance Checks

In the agent based models of aircraft, rail car, or truck fleets, or, in general, of any pools of assets that are subject to periodic maintenance
statecharts can be efficiently used to model the maintenance rules and the resulting availability of the assets. Consider an aircraft.
The periodic maintenance checks have to be done after a certain amount of time or usage. The most common checks are:

- A Check – due every month or each 500 flight hours; done overnight at the airport gate.
- B Check – due every 3 months; also done overnight at the gate.
- C Check – due every 18 months or each 9000 flight hours; performed at a maintenance base or at a hangar and takes about 2 weeks.
- D Check – due every 5 years; performed at a maintenance base and takes 2 months.

The statechart in this model can possibly be used for aircraft maintenance. When not on a maintenance, the aircraft is either Available, i.e. is
ready to fly, or in the Flight state. The transitions TakeOff and Landing can be triggered by timeouts.

Upon each landing the statechart determines if the aircraft is subject to maintenance, starting from the most “heavy” D Check. The
condition in a branch to DCheck state is: differenceInDateUnits( YEAR, DateOfLastDCheck, date() ) >= 5. Here date() is the current model
date, and DateOfLastDCheck stores the date of last D Check (it is updated be done in the transition from the DCheck state). If that condition
is false, the statechart evaluates the next one – for C Check: differenceInDateUnits( MONTH, DateOfLastCCheck, date() ) >= 18 ||
FlightHoursSinceLastCCheck >= 9000. The variable FlightHoursSinceLastCCheck is updated on each landing. It is important that when a
maintenance is done, it resets the dates and flight hours for itself and for all lighter maintenance types. The transitions outgoing the
maintenance states represent maintenance times: 2 * week(), 15 * hour, etc.