TRADEOFF ANALYSIS OF NON-DESTRUCTIVE INSPECTION TECHNOLOGIES
The Design of a System for Identifying Aircraft Fatigue Damage
Jeffrey Robbins, Rui Filipe Fernandes, Kevin Keller
System Engineering & Operations Research, George Mason University
Context
Need Statement & Design Alternatives
Aircraft of airlines must undergo regular preventative maintenance to meet
FAA airworthiness standards. Maintenance, repair, and overhaul companies are
tasked with inspecting and maintaining aircraft under strict timetables.
Average Fleet Age
Wide Spread Fatigue Damage
11
10.7
10.7
10.5
Years
10.5
10
Need: Reduce maintenance inspection cost experienced by airlines while improving the
quality and reliability of the inspection
Proposed Solution:
Implement new technology to reduce
the potential for human error.
Integrity Applications Inc.
Method of Analysis
Stochastic Simulation: Ten Representative Regions of Aircraft
Concept of Operation
Entity Attributes (Input)
Enhanced vs Automated
Technology utilized
Delivery method
Time distributions
Crack detection rates
Imaging Device
9.9
Track
Technology Alternatives
9.5
2010
2011
2012
Fatigue Cracks Around Rivets
2013
Year
Average aircraft fleet age has increased
8.1% from 2010 – 2013. Older aircraft are
more prone to fatigue-related damage.
Human Inspector
Crack Detection
+
0.42
0.44
9
Dollars (Billions)
4
3
2
1
20
45
70
95
8.38
8
7.14
7
Crack Detected
0.14
Type 1 Error
Autonomous Imaging Solution
of Exterior Surfaces
Delivery Method
Alternatives
Manual
Handheld (Contact)
Autonomous
Robotic Crawler (Contact)
Track or Robotic Arm (Non-contact)
9.44
9.13
7.5
Shape 5.008
Scale 9.652
N
12
5
Inspection Time (Minutes)
10
8.5
Gamma
0
Aircraft Maintenance Costs
9.5
Inspection Time of Lap-Splice Panels (Minutes)
6
Frequency
9
Synthetic Aperture Imaging
Thermographic Imaging
Laser Ultrasonic Imaging
Type 2 Error
Image Processing Identifies Surface
Deviations and Supports Decision Makers
With Detailed Diagnosis
Utility
Preliminary Utility Hierarchy
Time
Non-Functional
Maintainability
Key Benefits:
6.5
Output
Total Inspection Time
Region Inspection Time
Manual Labor Costs
Cracks detected
Type 1 Errors
Type 2 Errors
6
2010
2011
2012
2013
Year
Average annual maintenance costs have
increased 32.2% from 2010 - 2013.
Strict timetables lead to aircraft inspectors
missing or misdiagnosing 56% of cracks
and fatigue damage, which can lead to
catastrophic failure.
Enhance Human inspector Capability
or Replace With Automation
Type 2
Error Rate
Recommendations
As-Is Simulation (Unaided human inspector)
Simulated
Section Actual (mins) (mins)
1
122
116.47
2
28
27.83
3
75
75.38
4
68
67.71
5
37
36.1
6
104
105.64
7
95
100.23
8
35
34.68
9
16
15.2
10
48
49.56
Utility vs Cost chart
Sensitivity analysis
Link back to the context and need statement
Show how it creates a win-win.
Actual Total Sim Total Diff
(mins)
(mins) (mins) % err
628
Describe the implications of these results
Show how this solution closes the gap.
Within 1 minute of
expected value
628.81
0.81
<0.1%
Type 1
Error Rate
Reliability
Improved Detection of Structural Fatigue
Computer Aided Decision Support
Electronic Documentation
Preliminary Results
Preliminary Results
Quality