emerging nde technology for aging aircraft – large area
TRANSCRIPT
FAA William J. Hughes Technical Center
David G. Moore 505.844.7095Dennis P. Roach 505.844.6078Sandia National Laboratories
Federal Aviation Administration Airworthiness Assurance NDI Validation Center
Albuquerque, New Mexico 87185
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Dept. of Energy under Contract DE-AC04-94AL85000.
Emerging NDE Technology forAging Aircraft – Large Area ScanningTo Small High Resolution Systems
Maintenance Planning Tools
FAA William J. Hughes Technical Center
• Initiated in 1988 under the Aviation Safety Act
• Provides a mechanism to develop, evaluate, and assess new inspection technologies
• Partnerships with industry, academia, and government
FAA Airworthiness Assurance NDI Validation Center
FAA William J. Hughes Technical Center
• Aid in the development of new maintenance inspection techniques, validate improved structural repairs and advanced aircraft designs
• Perform inspection reliability studies
• Provide our customers with comprehensive, independent, and qualitative evaluations of new and enhanced inspection, maintenance, and repair techniques
• Facilitate the transfer of effective technologies into the aviation industry and develop inspection methods on a non-competitive basis
What We Do
FAA William J. Hughes Technical Center
What We Deliver (Information)Validation, technology transfer, and deployment
Information for inspection improvement (SBs, ADs,alternate-means-of-compliance requests, procedures)
Workshops, meetings, projects to promote technology transfer
Information to improve industry maintenance practices by
conducting reliability studies
Support development of new inspection technologies
Ongoing comparisons of conventional & emerging technology
FAA William J. Hughes Technical Center
• Disbond Inspection between lap joints• Corrosion Detection in thin and thick, Multi-Layered Joints • Surface Crack Detection (lap joints)• Interlayer Crack Detection (lap joints)• Widespread Fatigue Damage – 2nd layer cracks in WFD scenario• Corrosion Detection in Aircraft Joints• Composite Honeycomb Flaw Detection• Crack Detection Under-Raised Head Fasteners (1st/2nd layer; Rotorcraft)
A series of focused experiments that quantitatively & qualitatively evaluate NDI techniques through the use of blind testing & specific protocols to arrive at uniform comprehensive assessments.
Consider all factors that affect reliability including inspector, equipment, procedures, and environment – accuracy, sensitivity, repeatability, human factors, versatility, portability, scan rate, cost.
Validation Experiments
FAA William J. Hughes Technical Center
Large Area Inspections
• Disbond Inspection Infrared Techniques• Corrosion Detection Scanners (UT, ET)• Crack Detection Scanner (UT, ET)
subsurface and first layer • Composite Repair and Inspection new
equipment and inspection techniques
FAA William J. Hughes Technical Center
Disbonds can be precursors to crack initiation
• Boeing Service Bulletin 747- 53A2409 - find disbonds between 1st and 2nd layer
• Can be used to detect 1” x 1” disbonds under 0.10” of skin or less• Approved in Boeing NDT manuals as a general procedure for all
model aircraft
Fuselage Disbond Inspection ProcedureUsing Thermography
FAA William J. Hughes Technical Center
• Flash lamps heat theinspection surface
• Computer & imageprocessor make qualitativeand quantitative imagesand plots of the subsurfacestructure
• Infrared camera followsthe surface cooling
THERMAL WAVE IMAGING SYSTEM
HAND-HELD SHROUD,CONTAININGTWO FLASHLAMPS
INFRAREDCAMERA
LAPTOPCOMPUTER
EXTENSIONCARD-CAGEWITH IMAGEPROCESSOR
FLASHLAMPCONTROLLER
FLASHLAMPPOWER SUPPLY
HANDCART
IR Thermography
FAA William J. Hughes Technical Center
Ultrasonic Inspection Thermography Inspection
Bonded Doubler Disbonded Doubler Disbonded/BondedDoubler
B747 Experiments
FAA William J. Hughes Technical Center
Corrosion Detection System I
2120 2100 2080 2060 2040 2020
12
13
MATERIAL LOSS INDICATIONSG - 8% MATERIAL LOSS
H - 10% MATERIAL LOSS
I - 5% MATERIAL LOSSJ - 5% MATERIAL LOSS
11
FAA William J. Hughes Technical Center
Pulsed (Transient) Eddy Current (PEC) applies a broad-band pulse to a coil and generates a pulse magnetic field.
time t
Coil C
urrent
input current i(t)
time t
Magnetic Field
Hz(air)
Hz(specimen)
Hz =Hz(specimen) - Hz(air)
∆Hz(defect)
R
Hall effect probe
i(t) Hz(t)
Ferrite cup-core
Crack at Fastener
• Sensor watches decay of the reflected field• Range of interrogating frequencies to cover surface to deep flaws• Monitor response by time slice depending on inspection area
Corrosion Detection System II
FAA William J. Hughes Technical Center
0.01
0.1
1
10
100
0 5 10 15 20 25 30
Defect D iameter (mm)
Min
imu
m D
etec
tabl
e M
etal
Lo
ss (m
m)
1.534
4.55.5
78
9.511
DefectD epth(mm)
Defect Diameter (inches)0 0.80.40.2 0.6 1.0 1.2
Min
imum
Det
ecta
ble
Met
al L
oss
(inch
es)
0.04
4
0.0004
0.004
0.4
Defect Depth
(inches)
0.0600.1200.1600.1800.2400.2800.3200.3800.440
Corrosion Detection with Pulsed EC Trecscan System
FAA William J. Hughes Technical Center
Corrosion Detection- System III
• Well developed system fielded for Air Force applications
• Uses commercial ultrasonic transducer
• ACES coupling system is truly dripless
• Accommodates raised fasteners and surface distortions
• Durable and accurate X-Y Scanner
FAA William J. Hughes Technical Center
•Most of the techniques considered have no problem detecting 14% corrosion in .04 to .1 inch thick aluminum panels.
•Two ultrasound techniques have estimated 90% detection rates at approximately the 3% corrosion level.
•One eddy-current automated dual frequency technique has an estimated 90% detection rate at approximately the 2% corrosion level.
•System II not included in this study.
Corrosion Detection
FAA William J. Hughes Technical Center
• Fatigue crack specimens with comparison to industry baseline for conventional techniques deployed at airlines
• Small cracks under fastener heads (0.050”) were stressed• Improvements accompanied by increased training for
optimized signal interpretation
Rivet Check
MOI
Crack Detection 1st and 2nd Layer
FAA William J. Hughes Technical Center
Magneto Optic Imager Device
• Magneto-optic sensor images the perturbations in the magnetic field on a video display
• MOI 308 (1.5-200kHz) with 303 and 307 imager; rotating MOI (circular mag. field)
• Applications corrosion, surface and subsurface fatigue crack detections (transport to GA categories) in commercial and military
• Turbo MOI (prototype) - higher power and better eddy-current excitation for improved depth of penetration
Standard MOIHigh Power
Turbo MOIHigh Power (2X Standard)
0.200” 2nd layer crack
FAA William J. Hughes Technical Center
Rivet Head
Airframe Skin Fatigue Crack
Rivet Check
• EC distribution based on Self Nulling Probe (NASA)
• Eliminates signal variations associated with probe deployment & rivet misalignment – missed cracks
• Centering display (constant voltage) used to optimize probe position
Probe Positioning
Unflawed and Flawed Rivet Signals
FAA William J. Hughes Technical Center
Interlayer Crack Detection withJENTEK MWM GridStation
• Reliability of conformable probe system to detect cracks around fasteners of 3rd layer
• POD improvements over existing sliding probe procedures, with low false call rates. (0.9 PoD = .125” vs. 0.20+” for conventional NDI)
MWM-ArrayProbe
FAA William J. Hughes Technical Center
RFEC Technique for Flat Geometries
RFEC Probe
Drive Coil Pickup CoilDirect Coupling Path
Indirect Coupling Path• The RFEC probe is designed to focus on the indirect coupling path, so
that the signal measured by the pickup coil carries the information of the whole wall-thickness.
• Deeper penetration in detection deep flaws; higher S/N than LFEC
• Higher sensitivity and resolution to small defects
• Minimal signal interpretation is needed
FAA William J. Hughes Technical Center
Rotation Guide
Probe Carriage
Rotation Head
Test Panel
No crack
0.050” crack
Red = 2nd layer; Blue = 1st layer
Bottom of probe
showing two coils
FAA William J. Hughes Technical Center
Water Supply
Transducer in WeeperWater Column Housing
Gimbal Rotates AboutX and Y Axis
72 ply composite laminate
Validation of Ultrasonic InspectionsSix Ply Boron-Epoxy Test Specimen with
Engineered Flaws
Embedded Disbond and Delamination Flaws
6 PLYLAMINATE
Composite Inspection
FAA William J. Hughes Technical Center
ThermographyMAUS
System
SAM System
Shearography
Advanced Systems for Composite Inspection
FAA William J. Hughes Technical Center
SAM Image
Thermography (TWI) Image
MAUS Image
Shearography (LTI) Image
FAA William J. Hughes Technical Center
New Inspection Technologies
FAA William J. Hughes Technical Center
RD Tech Array Eddy CurrentHidden Corrosion Detection
•POD curves indicate detection capability comparable to other leading technologies currently in use by commercial and military maintenance facilities.
FAA William J. Hughes Technical Center
• Phased array! 128 element array with position encoder! Rubber coupled rotating tire over wet surface! Pulse-Echo mode! Initial application – disbonds in thick Airbus wing structure
• Principle of operation! Beam electronically configured and swept along array
Ultrasonic Wheel Array Sensor Instrument (NDT
Solutions Ltd.)
UT Phased Array
FAA William J. Hughes Technical Center
Results - wing (exfoliation corrosion)• UWASI scan
– 0.8 mm resolution– 100 mm x 400 mm area– Scan time 8 seconds– Pulse echo – Backwall echo gating
FAA William J. Hughes Technical Center
Summary
• The AANC provides a focal point for FAA nondestructive evaluation activities related to assessing advanced aircraft maintenance technologies and transferring the technology to use.
• As these technologies mature, the Center will continue to evolve and assess new technologies in order to fulfill the long term commitment to the FAA and aviation industry.
FAA William J. Hughes Technical Center
Questions?
http://www.sandia.gov/aanc/AANC.htm http://www.tc.faa.gov/