Aging Electrical Systems Research Program Prepared for: EAPAS Aging Aircraft Workshop November 6, 2002 Robert A. Pappas · Federal Aviation Administration Manager, Aging Electrical Systems Research Program ·AAR-480
Outline • Background • AFCB R&D • Flight Test Program • AFCB Specification • Pros/Cons of AFCB Installation • AFCB Implementation Considerations & Operational Issues • Future arc fault R&D • Wrap-up / Q&A
AFCB Purpose Mitigate the effects of electrical arcing on aircraft wiring.
Background:Current Inspection Technology • Current inspection and surveillance methods for aircraft wiring are limited in effectiveness and periodic in frequency. • Arc fault circuit breakers provide continuous monitoring & protection.
Background:Arc Faults • Present aircraft circuit breakers are designed to protect against over loads and short circuits. • Arcing faults draw less current than hard faults and are intermittent in duration. • Arcing faults can cause systems failures and fires.
Background:Typical Arcing Fault Arc Voltage and Current Waveform of Arcing Fault at 10,000 Feet
Background:Wire Degradation • Wiring insulation degradation increases with time do to a variety of factors such as: • Chaffing • Environmental stresses • Maintenance. • Degradation varies due to design, maintenance, and operational differences
Background:Commercial AFCI • 60 Hz AFCB’s are commercially available. • Aircraft AFCB’s must: • Be at least 50% smaller in size. • Operate in an aircraft environment. • Work in an aircraft electrical system. Photos courtesy Eaton Corp. and Texas Instruments
Background:Commercial AFCB Photo courtesy Eaton Corp.
AFCB Research and Development
AFCB Progress • Two R&D contracts awarded in December 1999 • Eaton Aerospace Controls • Hendry Telephone Products • September 2002: • Both contracts complete • 20 prototype AFCBs delivered and flight tested • 115V, 400 Hz • Smaller than the MS-24571 objective
AFCB Progress • Load and Power Characterization • Extensive load characterization • FAA B727 (N40) • Navy C-9 • Boeing Power Lab • Extensive power characterization • FAA B727 (N40) • Boeing Power Lab • Navy C-9 • Nuisance trip testing • FAA B727 (N40) • Boeing Power Lab
AFCB Progress Typical Flight Recorder Start-up (Current)
R&D Flight Test:Objectives • Fly AFCB’s on a variety of aircraft and electrical loads • Evaluate nuisance tripping • Demonstrate AFCB technology readiness for introduction into civilian and military transport aircraft.
AFCB Installation on Navy C-9 Aircraft (VR-56) First Navy Flight of Eaton AFCB on August 24, 2001
AFCB Installation on FAA B727 (N40) Eaton AFCB’s Data Recording
R&D Flight Test:FAA • B727 Flight Test Loads
AFCB Results • Eaton Flight Test • 30.9 Flight Hours • 228.2 Total Operational Hours • Hendry Flight Test • 99.2 Flight Hours • 793.6 Total Operational Hours Note: Does not include Navy C-9 flight test data or FAA ground time
AFCB Results • Flight Test Accomplishments • Several nuisance trip modes identified, corrected, and validated. • Several AFCB power supply problems identified, corrected, and validated. • Several AFCB hardware problems identified, corrected, and validated. • AFCB Technology ready for prime time.
AFCB Program Status • FAA has accepted and is currently processing two STC applications for AFCB installation • Limited installation • Non-critical circuits • Develop operational experience
AE-8B1 AFCB Performance Specification • Draft is nearly complete • Applicable to 115V/Single Phase devices only • Broad concurrence of the AE-8B1 committee members • AE-8B General Committee Ballot • SAE Council Level Ballot • Get the word out and support a YES vote on the specification ballot
AE-8B1 AFCB Performance Specification • All current requirements for thermal circuit breaker performance retained. • Arc Fault Specific Requirements: • Extensive • Rigorous • Represent and address REAL conditions
AE-8B1 AFCB Performance Specification • Guillotine Test
AE-8B1 AFCB Performance Specification • Guillotine Test
AE-8B1 AFCB Performance Specification • Wet Arc Test • Hot Re-Close Wet Arc Test • Cold Start-Up Time Test
AE-8B1 AFCB Performance Specification • Loose Terminal Test
AE-8B1 AFCB Performance Specification • Operation Inhibition (Masking) Test
AE-8B1 AFCB Performance Specification • Nuisance Trip Immunity (Arc Fault Discrimination)
AE-8B1 AFCB Performance Specification • Cross-Talk Immunity
AE-8B1 AFCB Performance Specification • Feedback Immunity Test
AE-8B1 AFCB Performance Specification • Other Arc Fault Performance Tests • Arc Fault Cycling (Endurance) • Temperature (DO-160) • Altitude (DO-160) • EMC (DO-160) • Susceptability – Radiated and Conducted • Emissions – Radiated • Lightning Induced Transients • Electrostatic Discharge
AE-8B1 AFCB Performance Specification • Other Arc Fault Performance Tests (Cont’d) • Power Quality (DO-160) • AFCB Reverse Installation – no adverse safety effects
AFCB Implementation • Prevents catastrophic damage to wiring system • Reduce arc energy for starting fires • Identifies circuits on which arc faults are occurring • Actively monitors circuits
AFCB Implementation • Determining Overload vs. Arc Fault vs. Nuisance Trip • Assurance of AFCB Functionality • Additional wire maintenance due to potential increases in trip rates from interconnect system degradation • Post trip troubleshooting, determining location of arc fault
AFCB Implementation • Fire and Smoke Incident Data • Maintenance Data • Reliability Data • Risk Analysis • Wiring Zones • SWAMP • Environmental Conditions • High Maintenance Areas • Avionics bay • Passenger Cabins • Cargo compartments
AFCB Implementation • Connected Equipment • Non-Flight Critical Equipment • Passenger/cargo • Flight Critical With Redundancy • Emergency Flight Loads • Risk Analysis • Functional/Physical • Intra-system hazards
Future AFCB R&D • Joint FAA, NAVAIRSYSCOM, ONR, USAF • 28VDC, 1-25A • Three-phase, 5-25A • MS3320 package • Communication interface • Remote control • Integration of 115V/400Hz AFCB and 28VDC into single breaker
Future AFCB R&D • Contract Awards Pending • Eaton Aerospace • AMETEK • Schedule • Year 1 – Prototype Demonstration • Possible Down Select • Years 2 & 3 – Engineering Development, Test and Evaluation
AFCB Conclusions • Present aircraft circuit breakers are not designed to mitigate the effects of arcing faults. • 115V/Single-Phase AFCB development is complete. • Select mitigation/prevention technology appropriate to the hazard.
Wire Test & Inspection Technology Wire Indenter Excited Dielectric Test Pseudo-Random Binary Sequence Reflectometry Broadband Impedance Measurement Smart Connectors Terahertz Reflectometry Neural Network Processing of TDR/FDR Waveforms Optical Chafe Detector Hi-Voltage Micro-Energy Pulsed Arrested Spark Discharge Validation Test Bed