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Live Fault Diagnostics for Wire Systems Dr. Cynthia Furse

Live Fault Diagnostics for Wire Systems Dr. Cynthia Furse Electrical & Computer Engineering, University of Utah Chief Scientist, LiveWire Test Labs Dr. James Stephenson LiveWire Test Labs August 25, 2014. The Problem – Faults in Flight. STS-93 Main Engine Controller.

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Live Fault Diagnostics for Wire Systems Dr. Cynthia Furse

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  1. Live Fault Diagnostics for Wire Systems Dr. Cynthia Furse Electrical & Computer Engineering, University of Utah Chief Scientist, LiveWire Test Labs Dr. James Stephenson LiveWire Test Labs August 25, 2014

  2. The Problem – Faults in Flight STS-93 Main Engine Controller Space Shuttle Columbia http://www.ksc.nasa.gov/shuttle/missions/sts-67/ images/medium/KSC-95EC-0396.jpg Probable Cause: Mechanical Damage during maintenance that went undetected until an arc event during launch.

  3. The Aging Wire Problem The polymer, Polyimide (Poly-X, Kapton, Stilan, Tefzel) -- chosen because it was a light weight insulator -- breaks down with time

  4. Implications of Electrical Faults • 10/2000, Continental Flight 1579, DC-9, electrical fire • 8/2000, AirTran Flight 913, DC-9, electrical fire • 9/98, SwissAir Flight 111, fatal accident • 1/9/98, United Airlines 767-200, electrical fire • 7/5/97, Northwest Airlines DC-9-15, electrical fire • 6/17/97, Sun Country Airlines, DC-10-10, smoke in aircraft • 2/20/97, Northwest Airlines DC-9-15, electrical fire • 1/11/96, Colombian DC-9-14, in-flight fire, fatal accident • 6/5/96, Delta Airlines 767-225, electrical fire • 6/6/96, Continental Express Beech 1900, in-flight fire • 7/96, TWA 800, fatal accident • 9/5/96, Federal Express DC-10-10, smoke in cabin • 12/11/96, US Air 757-225, in-flight fire

  5. Swiss Air 111: In Flight Entertainment Wiring Issues: Installation Abrasion Wire Guide Chaffing Proximity to sharp metal edges Tie-wraps and clamps Wiring of MD-11: http://www.swissair111.org/md11_wiring_photos.htm Installation and Design Issues: Issues Hidden – “Per Spec”

  6. Even New Wires Fail Cost to Replace is > $1M / plane Replacing Wires Would Not Solve the Problem % Probability of Failure of the Worst Polyimide Insulated Wire in each USN P-3 “Aircraft Location vs. Time”As of 5/7/95

  7. Wiring is a COSTLY problem US Navy Reports: • 1,101 mission aborts / year (401 in-flight aborts) • Average 2 in flight fires/month • 7.3 maintenance hours / flight hour due to wiring systems, alone • During a 10 year period, 6 aircraft LOST due to electrical failure • Effectively average 125 non-mission capable aircraft / year due to wiring • This information is known to be underreported The Challenges Facing U.S. Navy Aircraft Electrical Wiring Systems, Jerome Collins, 9thAnnual Aging Aircraft conference, March 2006

  8. What Causes Wiring Faults? Source: Navy Safety Center Hazardous Incident Data

  9. Detection is Not Sufficient Arc fault Detection Prevents Fire But also Prevents Location of Necessary Maintenance 10 A Thermal Breaker Tripped AFIC Tripped on “Wet Arc” Arc Fault Detection Needs a Complimentary Method to Locate the Faults

  10. Reflectometry Locates Faults Incident Pulse sent down wire Reflected Pulse comes back Time delay Time delay between Incident and Reflected Pulses tells distance to fault. The challenge: MANY faults cannot be replicated on the ground. “No Fault Found” (NFF). Intermittent faults must be located in flight. No other technology can do this. Tests Can’t Interfere with Aircraft Signals Aircraft Signals Can’t Interfere with Tests

  11. Types of Reflectometry • Time Domain Reflectometry (TDR) • Frequency Domain Reflectometry (FDR) • Spectral Time Domain Reflectometry (STDR) • Spread Spectrum Time Domain Reflectometry (SSTDR) • More …

  12. STDR / SSTDR CDMA Cell Phone Signal GPS Signal • Many Signals coexist • Noisy Channels OK • Interference / Jamming Rejection • Loss / Attenuation OK • Multiple Channels / Paths OK

  13. Energy in the Signal Energy Narrow Time– Interferes with Other Signals Broad Time – Can have Less (“no”) Interference with other signals. Energy TDR STDR Time Time

  14. Correlation Tells Time Shift Between Two Signals STDR: Pseudo Noise (PN) Code Incident Signal Reflected Signal Time Shift Correlation SHIFTS the signals. Multiplies ( x ) them. Integrates ( + ) them. Distance to Fault (meters) = Time Shift (s) x Velocity (m/s)

  15. Spectral Time Domain Reflectometry: STDR PN Code unknown time shift × PN Code known time shift ∫

  16. Spread Spectrum TDR: SSTDR Modulated PN code with unknown time shift × Modulated PN code with known time shift ∫

  17. MilStd 1553 Plus SSTDR

  18. SSTDR - Detecting & Locating a Wire Fault

  19. Reflectometry for Intermittent Faults • Intermittent faults only occur when aircraft is in use • Wires are LIVE • Tests cannot interfere with aircraft • Aircraft cannot interfere with tests • LiveWire uses a unique reflectometry signal that is immune to noise and non-interfering (SSTDR)

  20. AFCB vs. LiveWire Arc Fault Technology During the video LiveWire arc fault technology detected and reported the fault location more than 15 times prior to AFCB trip.

  21. LiveWire Intermittent Fault Technology • Real-time monitoring of LIVE Data and Power cables • Does not interfere with LIVE system operation • Single Solution for AC/DC Arc fault Detection & Location • 400 Hz and 60 Hz AC • Wide range of DC power (5,12, 28, 270) • Arc fault Detection in under 3ms • Precise Intermittent Fault Location +/- 1% • Test LIVE cables 1 – 1000+ feet

  22. Boeing 747 Live Arc Fault Testing on Aircraft • FAA test aircraft (Boeing 747 at Sandia National Labs) • 400Hz arc fault testing, EE-bay • Intermittent fault detection/location • Realistic electrical systems live (power kart) • Non-ideal aircraft wiring • System cross-talk analysis -- LiveWire didn’t interfere with aircraft, aircraft didn’t interfere with LiveWire.

  23. LiveWire Technology Tested on Boeing 747 Boeing funded arc fault test preparations WILMA Inline connection to secondary power circuit Breaker panel, EE-bay

  24. LiveWire Technology Tested on Boeing 747 Aircraft power circuit extended to Guillotine fixture AFCB added inline with thermal breaker Guillotine arc fault test fixture

  25. LiveWire Technology Tested on Boeing 747 During the video LiveWire arc fault technology detected and reported fault location. Circuit breakers didn’t trip!

  26. Other LiveWire Technology Tests • FAA test aircraft (Boeing 747 at Sandia National Labs) • 400Hz arc fault testing, EE-bay • Intermittent fault detection/location • MIL-STD 461f Validation • V22 Testing at New River • Fully operational aircraft systems • Built-In System Test • Verified no adverse effects on plane and or LW system

  27. LiveWire Technology MIL-STD 461F Testing WILMA

  28. Commercialization

  29. LiveWire Aircraft Live System Wiring Analyzer • Flight line portable • LIVE system fault Detection & Location • Intermittent & hard open/short • Simple user interface • Detect & Locate Arc-Faults > 2ms • Data storage and download

  30. And You Can Read it….

  31. And Reflectometry Plots for Those Who Use Them

  32. Typical Arc Fault Test Setup • Loads • Various 400Hz LRUs • 3-phase motors • Resistor banks • DC lights • AC/DC brushed motors • Switching AC/DC loads • Sources • 400Hz, 120VAC • 270 VDC • 28 VDC • 5 VDC • 1800Hz, digital signal

  33. ACKNOWLEDGEMENTS Development of this technology was funded by: • NAVAIR • AFRL • FAA • NASA • Boeing • Utah Centers of Excellence Program • National Science Foundation (NSF) • Corporate Development Partnerships

  34. Commercialization

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