Date post: | 18-Dec-2015 |
Category: |
Documents |
Upload: | ursula-whitehead |
View: | 220 times |
Download: | 0 times |
1
S ystemsAnalysis LaboratoryHelsinki University of Technology
A Simulation Model for Aircraft Maintenance in an Uncertain Operational Environment
Ville Mattila, Kai Virtanen and Tuomas Raivio
Systems Analysis LaboratoryHelsinki University of Technology
2
S ystemsAnalysis LaboratoryHelsinki University of Technology
Objective
• Simulation of flight and maintenance operations of the aircraft fleet of the Finnish Air Force (FiAF)
• Importance for maintenance designers– Predicting supportability requirements
– Evaluating performance of operating policies
• Special interest in operations of crisis situations– Uncertainty due to limited knowledge of such
circumstances
3
S ystemsAnalysis LaboratoryHelsinki University of Technology
Flight and maintenance operations• A complex logistic system
– Overall performance greatly influences the fleet’s operational capability
Flight policy
Periodic maintenance
Failure and damagerepairs
Equipment reliability
Personnelresources
Supply of materials
Operatingconditions
Crisis situations
4
S ystemsAnalysis LaboratoryHelsinki University of Technology
Operational environment
• The fleet operates under a threat of an enemy
– Limited knowledge of actual encounters
Uncertainty of operating conditions
Uncertainty of model parameters and model form
5
S ystemsAnalysis LaboratoryHelsinki University of Technology
Flight operations in crisis situations
• Increased and uneven flight intensity– Reacting to enemy’s actions
• Engagements– Battle damages
6
S ystemsAnalysis LaboratoryHelsinki University of Technology
Maintenance operations in crisis situations
• Changed maintenance requirements– Emphasis on battle damage repairs
– Varying intensity
• Decentralization of airbases– Maintenance facilities threatened by
the enemy
• Specialized maintenance personnel
• Uncertain supply of materials
7
S ystemsAnalysis LaboratoryHelsinki University of Technology
Uncertainty in model construction
• Construction based on incomplete information
– Emphasis of expert knowledge
– Experience of normal operations
– Live exercises and contingency plans
• Ambiguity in defining the model
User is allowed the flexibility to describe a variety of operating policies and conditions
8
S ystemsAnalysis LaboratoryHelsinki University of Technology
The simulation model
• Discrete-event approach
• Features– 3 squadrons operating
from own airbases
– Central depot-level maintenance facility
– Periodic maintenance, failure, and damage repairs
– Personnel and material resources
• Implemented with Arena-software
9
S ystemsAnalysis LaboratoryHelsinki University of Technology
Structure of the model
Class I airbase
Class II airbases, up to 3
Mission
Failures
Damages
Need forperiodic
maintenance?
D-level maintenance Fuel and materials supply
Destroyedaircraft
3 Squadrons
Everyday maintenance
I- level maintenance
O-level maintenance Wait
Everyday maintenance
Damage repair
O-level maintenanceWait
Mission generation
10
S ystemsAnalysis LaboratoryHelsinki University of Technology
Model validation
• Evaluation by subject matter experts– Assumptions, results
– Various groups of FiAF personnel
– In different phases of the modeling effort
• Comparison of results– To reference data from normal operations
– To results of an earlier tentative simulation study
11
S ystemsAnalysis LaboratoryHelsinki University of Technology
Example analysis
• Changing maintenance policy during a crisis– Periodic maintenance is discarded to release
resources to other activities
– How does the change affect aircraft availability?
• A scenario with 4 phases1 Increased flight intensity
2 Further increase in the amount of flights, decentralization of airbases
3 Aerial battles
4 Decreased flight intensity due to losses
12
S ystemsAnalysis LaboratoryHelsinki University of Technology
Results
• Change in policy is necessary to sustain operational capability
0
0.2
0.4
0.6
0.8
1
0 50 100 150 200 250
Time (days)
Av
aila
bili
ty
In 1st phase In 2nd phase
In 3rd phase Not employedEmployment of new policy
1. 2. 3. 4.
13
S ystemsAnalysis LaboratoryHelsinki University of Technology
Conclusions
• A model for fleet operations in an uncertain operational environment– Quantitative assessment of maintenance
policies in crisis situations
• Implementation with a graphical simulation software– Easily manageable simulation analyses for
maintenance designers
– A tool for training of maintenance personnel