A Simulation Model for Aircraft Maintenance in an Uncertain Operational Environment

1. A Simulation Model for Aircraft Maintenance in an Uncertain Operational Environment Ville Mattila, Kai Virtanen and Tuomas Raivio Systems Analysis Laboratory Helsinki University of Technology

2. Objective • Modeling and simulation of flight and maintenance operations of the aircraft fleet of the Finnish Air Force (FiAF) • Prediction of supportability requirements and fleet performance • Effect of operating conditions • Effect of operating policies and supposed system improvements • Special interest in conflict operations • Uncertainty involved in the operational environment

3. Development Early considerations in FiAF, static failure models Initiative for simulation of aircraft maintenance, joint project between FiAF and Systems analysis laboratory Discrete-event simulation as approach, Arena software as tool Simulation model of one airbase Model with multiple airbases, normal and conflict operations A simulation tool for FiAF Introduction in FiAF Simulation of helicopter maintenance Scheduling of aircraft maintenance 2000 2004

4. Discrete-event simulation • Widely applied in analyzing logistic systems • Conceptually simple approach • Intuitive consideration of uncertainty • Allows the inclusion of highly complex processes and interactions in a model • Possibilities for visualization • Powerful software tools for model construction and analysis, flowchart modeling

5. Aircraft availability • Reliability • Deterioration • Preventive measures • Maintenance • resources • operating policies • environment • Battle damages • threat scenarios • tactics • Flight activities • modes of flying • intensity • selection of aircraft

6. Conflict operations • Limited knowledge on how the presence of the enemy affects the fleet’s operations • Unpredictable flight pattern • Battle damage rates • Changed maintenance requirements • Decentralization of airbases • Material supply • Assaults on airbases

7. The simulation model Aircraft availability

8. Construction and validation of the model • Based on incomplete information • Emphasis on expert knowledge • Conversations with FiAF representatives • Presentations to maintenance professionals • Available data on normal operations, exercises and contingency plans • Affects the way the model can be used • Definition of input data • Interpretation of results • Sensitivity analyses

9. Utilization of the model • Implemented with Arena -software • Appears as a stand-alone tool to the user • Customized user interface and simulation reports • Simulation analyses for maintenance designers • Allocation of maintenance personnel, spare parts and equipment • Comparison of flight and maintenance policies • Effect of reliability improvements... • Applicable for training of maintenance personnel • Demonstrates the significance of maintenance and support logistics to performance of the fleet

10. Example analysis • Change of maintenance policy during a dynamically evolving conflict • Periodic maintenance is suspended to release aircraft to flight activities • At what time should this occur? • A scenario with 4 phases • Increased flight intensity • Further increase in flight intensity, decentralization of airbases • Aerial battles • Decreased flight intensity due to losses

11. Example analysis: results

12. Conclusions • A simulation model for the aircraft fleet of FiAF • Quantitative assessment of supportability requirements and fleet performance • Diverse operating policies and conditions • A tool for maintenance designers and training of maintenance personnel • Introduced to Air Force units