NTSB INVESTIGATION INTO

TWA FLIGHT 800SYSTEMS

Robert L. SwaimSystems Group Chairman

The Regular Systems Group included people from:

Airline Pilots Association (ALPA)Boeing Crane Corp., (Lear-Romec and Hydro-Aire Divisions)Federal Aviation Administration (FAA)Honeywell CorporationInternational Association of Machinists & Aerospace Workers (IAMAW)National Aeronautics and Space Administration (NASA)Trans World Airlines (TWA)United States Air Force (USAF)United States Navy

And many others.

SYSTEMS GROUP ACTIVITIES

EXAMINATIONS OF WRECKAGEEXAMINATIONS OF WRECKAGE AT CALVERTONAT CALVERTON AT AIR FORCE RESEARCH LABAT AIR FORCE RESEARCH LAB AT BOEING AND HONEYWELLAT BOEING AND HONEYWELLEXAMINATIONS OF AGING AIRPLANESEXAMINATIONS OF AGING AIRPLANESRESEARCH INTO PRIOR ACCIDENTS/INCIDENTSRESEARCH INTO PRIOR ACCIDENTS/INCIDENTSWIRE DATA SEARCHWIRE DATA SEARCHLAB TESTS INTO:LAB TESTS INTO: POLY-X SHORT AND ARCING PROPERTIESPOLY-X SHORT AND ARCING PROPERTIES SHORTS WITH WET AND DRY CONTAMINANTS SHORTS WITH WET AND DRY CONTAMINANTS PROPERTIES OF AGED POLY-X PROPERTIES OF AGED POLY-X PROPERTIES OF OTHER AGED WIRE TYPES PROPERTIES OF OTHER AGED WIRE TYPES

• Fuel Pumps,• Jettison/Override• Scavenge• Electrical Failures• Fuel Quantity Indicating System (FQIS)• Hot Air From Pressurization and• Air Conditioning• Fuel Tubes• Vent System Fires• Sparks Created by Static or Lightning• Main Landing Gear Well Fires/Problems

Possible Ignition SourcesDiscussed at Public Hearing

FAA NPRM 99-18 IDENTIFIED 29 DESIGN FEATURES, MALFUNCTIONS, FAILURES, AND MAINTENANCE-RELATED ACTIONS AS DEFICIENCIES.

THE LIST INCLUDED:

18 FUEL PUMP & CONNECTOR DEFICIENCIES. (PLUS WIRING INSIDE CONDUITS IN FUEL TANKS)

6 BONDING & ELECTROSTATIC DEFICIENCIES.

5 FQIS PROBE & WIRING DEFICIENCIES.

Beyond the examples cited in NPRM 99-18 areadditional potential ignitionsources, such as:

Localized heating of tank wallfrom external sources such aslanding gear or pack bay fire,

Engine burst, cargo shift, orother possible causes ofpuncture to fuel tank structure.

FURTHER POTENTIAL IGNITIONSOURCES EXIST

TYPICAL 747 CWT INTERIOR,FORWARD OF WHEEL WELL

APU LINE

JETTISON / FILLMANIFOLD

SCAVENGEPUMP >

FQISWIRES

< LEFT FILLVALVE

<REAR SPAR>

Recorded Comment About ”Crazy” #4 Fuel Flow, About 2.5Minutes Prior To The Explosion.

Loss of Power Within 1/4 Second.

CVR Background Noise Drop-outs Twice In The Last Second ofRecording.

Recovered CWT Gage Read More Than Double the ValueRecorded at JFK.

Repeated Lighting and Refueling Squawks.

ELECTRICAL ANOMALIES WERE RECORDED

RESOLIDIFIED COPPER AND BLACKENED WIRE INSULATION (POSSIBLE INDICATIONS OF SHORT CIRCUITS),DRILL SHAVINGS ALONG WIRE PATHS,BLACKENED MARKS ON STRUCTURE NEXT TO WIRE ROUTES,SILVER SULFIDE DEPOSITS ON FUEL TANK COMPONENTS,DAMAGED WIRE INSULATION (FROM BOTH INSIDE TANKS AND OUTSIDE),

NO PHYSICAL EVIDENCE WAS A DIRECT SOURCE OF IGNITION.

PHYSICAL EVIDENCE FROM THEWRECKAGE TO BE DISCUSSED :

BASIC ELECTRICAL SYSTEM

COCKPIT

ELECTRICAL / EQUIPMENTCOMPARTMENT (E/E)

GENERATORS(4 ENGINE, 1 APU)

ELECTRICAL POWER IS GENERATED AT EACH ENGINE AND THE APU.

COCKPIT (& OTHER) SWITCHES ARE USED TO DISTRIBUTE POWER

THROUGH-OUT THE AIRPLANE FROM THE E/E.

CONTROLS

RADIOS LIGHTS

INDICATORS APU

PERSON STANDING ON CWT TO EXAMINE RACEWAY

BASIC ELECTRICAL SYSTEMWIRES ARE GROUPED INTO BUNDLES

BUNDLES ARE GROUPED INTO RACEWAYS

ADD John Schade’s moving video of theELECTRICAL SYSTEM

SINCE THE FUEL GAGES ARE ELECTRICALLYCONNECTED TO THE FUEL TANKS:

COULD THE FUEL QUANTITYINDICATION SYSTEM (FQIS) HAVE

IGNITED VAPORS?

Example of previous FQIS-involved accident:January 14, 1992, Navy C-130 accident near Cambridge, Maryland.

SEVEN FUEL PROBES, ONE COMPENSATOR, & WIRES IN TANK

PHOTO OF COMPENSATORAT BASE OF PROBE

WHAT IS THE FQIS?

A 3-WIRE SET CONNECTSTHE PROBES TO A COCKPIT GAGE

CWTCWTGAGEGAGE

LeftLeftWingWing

RightRightWingWing

FLIGHT ENGINEER FUEL PANEL

HOW DOES THE FQIS OPERATE?HOW DOES THE FQIS OPERATE?(SIMPLIFIED PRINCIPLE)(SIMPLIFIED PRINCIPLE)

1) AIRCRAFT SYSTEM SUPPLIES INDICATOR WITH 115 VAC ELECTRICITYTHROUGH CONNECTOR

FUELQUANTITYINDICATOR

DISPLAY

FUEL PROBE IN TANK

2) POWER TRANSFORMEDTO LOWER VOLTAGES

INSIDE INDICATOR

SIMPLIFIED FQIS OPERATING PRINCIPLESIMPLIFIED FQIS OPERATING PRINCIPLE

3) THE TRANSFORMER ISCONNECTED TO OUTER TUBE (HI-Z) OF PROBE IN FUEL TANK.

FUEL BETWEEN TUBES CHANGES(CAPACITANCE) AMOUNT OF ELECTRICITY REACHING CENTER TUBE.

SIMPLIFIED FQIS OPERATING PRINCIPLESIMPLIFIED FQIS OPERATING PRINCIPLE

4) ELECTRICITY FROMINNER TUBE (LO-Z) OF

PROBE IS USED TO DRIVEMECHANICAL ANALOGAND DIGITAL DISPLAYS

SIMPLIFIED FQIS OPERATING PRINCIPLESIMPLIFIED FQIS OPERATING PRINCIPLE

000.0DISPLAY

FACE

CWT FQIS DISPLAY

From the recovered CWT gage: 640 pounds of fuel displayed on face. Electrical position in gage similar to face.

The 640 pound display was more than doublethe 300 pound value recorded at JFK.

(PHOTOGRAPHS OF TWA800 CWT GAGE

(CONNECTOREND)

(DISPLAYEND)

CWT FQIS DISPLAYCWT FQIS DISPLAY

Question: Could the Question: Could the twotwo display readings display readingshave been in error?have been in error?

Conclusion: The gage was probably indicating the Conclusion: The gage was probably indicating the electrical position that it received from the system.electrical position that it received from the system.

Specification 60B92010 tolerance at zero display was +/- 0.10% of full scale (.10% X 84,000 = 84 pounds)

Boeing flight test found 260 pounds remained at end of scavenging.

Boeing ground calibration of another airplane found display to be 143 to 238 pounds high.

RED ARROWS POINT TO FQIS WIRE CHAFES IN B-747

CWT (N93117)

THEREFORE, COULD THE GAGE ERROR ANDOTHER EVIDENCE HAVE A COMMONALITY?

2. ENERGY RELEASED IN TANK:

1. ENERGY ENTERS WIRES OUTSIDE OF TANK:

(LECTROMEC DEMOWITH POLY-X WIRESFROM RETIRED B-747)

WIRE SEPARATION FOUND NOT TO BE HOWILLUSTRATED BY BOEING:

[View from beneath in BoeingProduction Illustration 61B70118:]

PERSON STANDINGON (GREEN) CWT TO EXAMINE RACEWAY

SEGREGATION BETWEEN BUNDLES LOST,

CONTAMINATION OF MANY TYPES (SHAVINGS, FLUIDSTAINS, LINT).

CO-ROUTING OF WIRES (DESIGN & INADVERTENT):

TANK WIRING IN WINGS

WITH POWER OUTSIDE OF TANKS

MODIFICATIONS NOT TO STANDARD PRACTICES,

CRACKED WIRE INSULATION

MAINTENANCE / AGING FINDINGS IN OTHERAIRPLANES TO BE DISCUSSED LATER:

Could change following series to a moving video toshow each layer of the FQIS SYSTEM

THE GROUP EXAMINED WHAT IS ROUTEDTHE GROUP EXAMINED WHAT IS ROUTEDWITH THE CWT FQIS AND FOUND:WITH THE CWT FQIS AND FOUND:

CWTGAGE

LeftLeftWingWing

RightRightWingWing

CWT HAS 7 PROBES & 1 COMPENSATOR.FURTHER ILLUSTRATIONS SHOW ONLY ONE PROBE & COMPENSATOR.

THE GROUP EXAMINED WHAT IS ROUTEDTHE GROUP EXAMINED WHAT IS ROUTEDWITH THE CWT FQIS AND FOUND:WITH THE CWT FQIS AND FOUND:

CWTGAGE

LeftLeftWingWing

RightRightWingWing

MAINTENANCE RECORDS OF A GALLEY (C) WATER LEAKOVER WIRE ROUTE MISSING

FQIS WIRES.

CWTGAGE

TOTAL-IZER

LeftLeftWingWing

RightRightWingWing

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(GROSS WEIGHT & TOTAL FUEL QUANTITY INDICATOR)(GROSS WEIGHT & TOTAL FUEL QUANTITY INDICATOR)

WIRE SPLICE

CWTGAGE

TOTAL-IZER

LeftLeftWingWing

RightRightWingWing

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(TOTALIZER CONNECTOR)(TOTALIZER CONNECTOR)

115 VAC & WIRES FROM OTHER TANKS

USE COMMON CONNECTOR

CWTGAGE

TOTAL-TOTAL-IZERIZER

LeftLeftWingWing

RightRightWingWing

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(BRIDGE FOUND IN TOTALIZER CONNECTOR)(BRIDGE FOUND IN TOTALIZER CONNECTOR)

AN IMPROPER REPAIR HAD BRIDGED PINS INTHE CONNECTOR FOR CWT AND THE RIGHTWING THEN CRACKED. THE CRACK WASBRIDGED IN TESTS AT ABOUT 270 VOLTS.

MICROSCOPIC VIEWINSIDE OF CONNECTOR

CWTGAGE

TOTAL-IZER

LeftLeftWingWing

RightRightWingWing

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(SHORT THROUGH TOTALIZER?)(SHORT THROUGH TOTALIZER?)

THEREFORE, A SHORT TO THE RIGHTWING TANK FQIS MAY HAVE REACHEDTHE CWT.EVIDENCE OF MOLTEN WIRES (POSSIBLYSHORT CIRCUITING) WERE FOUND AT THERIGHT WING ROOT, BUT WERE BELIEVED ITTO BE CAUSED BY FIRE.

?

CWTGAGE

TOTAL-IZER

LeftLeftWingWing

RightRightWingWing

AIDSUNIT

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(AIRBORNE INTEGRATED DATA UNIT ADDED)(AIRBORNE INTEGRATED DATA UNIT ADDED)

WIRE SPLICE

CWTGAGE

TOTAL-IZER

LeftLeftWingWing

RightRightWingWing

AIDSUNIT

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(AIRBORNE INTEGRATED DATA PROTECTION)(AIRBORNE INTEGRATED DATA PROTECTION)

THE AIDS UNIT ALSO HAS WIRING FROMEACH OF THE TANKS, PLUS POWER.

BLACKENED STRUCTURE WAS FOUNDALONG WIRE ROUTE.

HOWEVER, A PROTECTIVE RESISTOR NEARTHE FLIGHT ENGINEER STATION ISOLATES

THE MAJORITY OF THIS CIRCUIT.

CWTGAGE

TOTAL-IZER

RightRightWingWing

AIDSUNIT

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(ELECTRICAL TEST FOUND TANKS NOT ISOLATED)(ELECTRICAL TEST FOUND TANKS NOT ISOLATED)

LeftLeftWingWing

TESTING IN ANOTHER AIRPLANE FOUND THATELECTRICAL SIGNAL APPLIED TO CWT WIRE WAS

DETECTABLE ON LEFT WING TANK WIRE

PressurePressureRefuelingRefueling

PanelPanel

CWTGAGE

TOTAL-IZER

VSOCMPTR

LeftLeftWingWing

RightRightWingWing

AIDSUNIT

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(GROUND REFUELING SYSTEM INCLUDES ALL TANKS)(GROUND REFUELING SYSTEM INCLUDES ALL TANKS)

WIRE DIAGRAM REVIEW AND TESTINGFURTHER FOUND THAT CIRCUITS ARE

NOT ISOLATED TO EACH TANK.

CVR WiresCVR Wires

INTERNAL WIRES CONNECT 747 FUEL TANKS

TYPICAL CONNECTION BETWEENRIGHT WING TANKS & LEFT

WING REFUEL PANEL

PressurePressureRefuelingRefueling

PanelPanel

CWTGAGE

TOTAL-IZER

FUELFLOW

VSOCMPTR

FUELFLOW

CMPTR

LeftLeftWingWing

RightRightWingWing

AIDSUNIT

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(FUEL FLOW #4 INDICATION ADDED)(FUEL FLOW #4 INDICATION ADDED)

To Engine #4

ParallelParallelCVR WiresCVR Wires

PressurePressureRefuelingRefueling

PanelPanel

CWTGAGE

TOTAL-IZER

FUELFLOW

VSOCMPTR

FUELFLOW

CMPTR

LeftLeftWingWing

RightRightWingWing

AIDSUNIT

To Engine #4To Engine #4

SIMPLIFIED FQIS-RELATED CIRCUITSSIMPLIFIED FQIS-RELATED CIRCUITS(MISSING AREA & LIGHTING WIRES ADDED)(MISSING AREA & LIGHTING WIRES ADDED)

LIGHTS

(MISSING

WIRES)

ABOUT HALF OF CWT FQIS-ASSOCIATED WIRES WERE FOUND.

PLACEHOLDER FOR:

SLIDE SHOWING BOEING D6-_______SPECIFICATION SENTENCE THAT STATES

FQIS NEEDS NO SEPARATION ORPROTECTION.

CHAFE

BUNDLES BEHIND FLIGHT ENGINEER

PANEL

SISTERSHIPPHOTOS

MAIN DECK ROUTE OF WIRES FOR FUEL TANKS, LIGHTING,

& FUEL FLOW

SISTERSHIPPHOTOS

VIEW UPWARD

VIEW AFT & UP

WIRES TO VSO AND FUEL FLOW 4

SISTERSHIPPHOTOS

SISTERSHIP IMAGE FROM INSIDE, SO IS OPPOSITE THE ORIENTATION SHOWN ABOVE

WIRE ROUTE BENEATH FLIGHT ENGINEER STATION

ParallelParallelCVR WiresCVR Wires

PressurePressureRefuelingRefueling

PanelPanel

CWTGAGE

TOTAL-IZER

FUELFLOW

VSOCMPTR

FUELFLOW

CMPTR

LeftLeftWingWing

RightRightWingWing

AIDSUNIT

To Engine #4To Engine #4

LIGHTS

(MISSING

WIRES)THE ROUTE BETWEEN THE FLIGHT ENGINEER

STATION AND THE AVIONICS BOXES HAS CIRCUITS FROM EACH OF THE ELECTRICAL ANOMALIES,

EXCEPT THE CVR DROP-OUTS.

THE CVR WIRES ARE BUNDLED WITH LEFT WING FQIS AND OTHER WIRES WHICH ALSO GO THROUGH THE

ROUTE BETWEEN THE FLIGHT ENGINEER AND AVIONICS.

The CVR records cockpit noise at different locations. Electricainterference was also recorded on each channel and samples of the recorded Captain’s channel are shown below.

The interference on the Captain’s channel was missingtwice in the last second. These drop-outs were not found on other channels or on other CVR recordings.

(NORMAL 400 HERTZ FREQUENCY THAT

ELECTRICITY IS GENERATED AT)

NORMAL RECORDING

REL

ATI

VEST

REN

GTH

FREQUENCY

BACKGROUND NOISE MISSING DURING 2

DROP-OUT INTERVALS

FREQUENCY

REL

ATI

VEST

REN

GTH

Electrical tests on a 747 were conducted for the NTSB bypersonnel from the Naval Air Warfare Test Center. Switchingdid not transfer enough energy to fuel tank wires to reachminimum ignition energy.

The testing did find that background noise energy wasproduced by numerous electrical devices that had wiresrouted in bundles with a CVR wire.

The testing did show that the CVR background noise coulddrop out (be interrupted) when heavy electrical loads wereswitched on and off.

ENERGYPowered

wiresCVRwire

NOTE: SHOW TWA ENGINEERING MODIFICATIONORDER IN BACKGROUND TO SHOW THAT OTHER

WIRE ROUTES MAY HAVE EXISTED

ALTHOUGH A COMMON WIRE ROUTE WAS FOUND, OTHER ROUTES MAY HAVE EXISTED.

SHORT CIRCUITS ARE A FORM OF SWITCHING.COULD DRILL SHAVINGS LEAD TO SHORT

CIRCUITS?

DRILL SHAVINGSIN WRECKAGE

DRILL SHAVINGS ON WIRE BUNDLESBENEATH REPAIR

REPAIRED FLOOR STRUCTUREIN 747 SISTERSHIP

DRILL-SHAVING SHORT CIRCUIT TESTSCONTRACTED TO LECTROMECHANICAL DESIGN LABORATORY

SHAVINGS CUT THROUGH SOME WIRE INSULATION.SHAVINGS CUT THROUGH SOME WIRE INSULATION.OTHER SHAVINGS WERE SHED BY INSULATION.OTHER SHAVINGS WERE SHED BY INSULATION.SHAVINGS WERE ABLE TO TRANSFER ENERGY.SHAVINGS WERE ABLE TO TRANSFER ENERGY.

THE SHORT CIRCUITS WERE STOPPED BY THE SHORT CIRCUITS WERE STOPPED BY CIRCUIT BREAKER TRIPS OR MELTING CIRCUIT BREAKER TRIPS OR MELTING OF SHAVINGS.OF SHAVINGS.

SHAVING IN WIRE BUNDLESHAVING IN WIRE BUNDLE

PLACEHOLDER FOR

Raceway diagram or still-image from John’s video,surrounded by photos ofINDIVIDUAL REPAIRSfound along FQIS path inaccident airplane.

TESTING AT RAYTHEON (THE FORMER NAVAL AVIONICSFACILITY) FOUND THAT 20% OF WIRE DAMAGE PENETRATED TO THE CORE.

CRACKED WIRE INSULATION WAS ALSO COMMONLY FOUND IN THE WIRE INSULATION OF OLDER AIRPLANES.

CONDENSATION AND SPILLED FLUIDS WERE COMMONLY FOUND IN TRANSPORT AIRPLANES. 747 WIRE BUNDLE

ON COCKPIT FLOOR IN MIDST OF FLUID STAINS

CRACKED WIRE INSULATION

FROM 747

DUAL LAYER POLY-X DID NOT ARC-TRACKDUAL LAYER POLY-X DID NOT ARC-TRACK

TOILET FLUID SHORTED SAME AS WATERTOILET FLUID SHORTED SAME AS WATER

WET SHORTS COULD BE MAINTAINED FORWET SHORTS COULD BE MAINTAINED FOR LONG PERIODS. LONG PERIODS.

(PHOTO OF WIRES (PHOTO OF WIRES AFTER 5 MINUTES AFTER 5 MINUTES

OF WET-SHORT)OF WET-SHORT)

WET SHORT CIRCUIT TESTSCONTRACTED TO LECTROMECHANICAL DESIGN LABORATORY)

PLACEHOLDER FOR CIRCUIT PROTECTIONCircuit breakers to use AFRL cut-away view

Resistors to ground?Arc Fault Circuit Breakers (AFCB)

Circuit protection also may not be effective for unrecognized connectionsbetween circuits, such as through totalizer.

IN SUMMARY, OUTSIDE OF THE CWT WERE:RECORDED (INCLUDING FQIS DISPLAY) AND PHYSICAL EVIDENCE OF AT LEAST ONE ELECTRICAL EVENT.

DAMAGE AND/OR CONTAMINATION IN WIRING OF OTHER AIRPLANES.

RECORDS OF PRIOR SHORT CIRCUITS AND FQIS INVOLVEMENT IN IGNITION.

AT LEAST ONE WIRE ROUTE THAT BROUGHT TOGETHER ALL OF THE SYSTEMS THAT HAD ELECTRICAL ANOMALIES.

EVIDENCE THAT ELECTRICITY ENTERING THE FQIS OF LEFT OR RIGHT WING TANKS COULD REACH THE CWT.

TESTING THAT FOUND SHORT CIRCUITS CAN TAKE PLACE FOR LONGER THAN THE FLIGHT OF TWA 800.

NEED BETTERCOCKPIT PHOTO

FROM INSIDE OF THE TWA800 FUEL TANKS:

ONLY ABOUT 4 FEET OF CWT WIRE AND LESS THAN TWO TERMINAL BLOCKS TO WORK WITH.

UNAPPROVED WIRE PRAC-TICES WERE FOUND IN WING FUEL TANKS.

LITTLE USEFUL DATA WAS OBTAINED FROM RECOVERED CWT FUEL PROBE FRAGMENTS.

(Dry Bay)

CWT Wire and Probe Installations

RightWing

LeftWing

PHOTO IN ANOTHER 747 SHOWS AMOUNT OF RECOVERED

TWA 800 CWT FQIS WIRE

IN OTHER 747 AIRPLANE FUEL TANKS WERE:

0.0415 inch

B-747 N93105

B-747 N93117

CHAFECHAFE

TERMINAL BLOCKS AND METAL CLAMPS THAT DAMAGED WIRE INSULATION AT FUEL PROBES.

CHAFED FQIS WIRES.

IN OTHER 747 AIRPLANE FUEL TANKS WERE:

INSERT PHOTO

nsulation thinned and splith to the conductor

PHOTO SHOWS SPLIT FQIS WIRE & BLACK SULFIDE DEPOSITS

(FROM B-747 N93105)

FINE WIRE IN A CWT PUMP INLET (NPRM 99-18 DISCUSSED POTENTIAL ELECTRICAL HEATING OF FINE FILAMENTS).

WIRE INSULATION SPLITS THATEXPOSED CONDUCTORS

COPPER AND SILVER SULFIDES IDENTIFIEDIN TWA 800 WRECKAGE & OTHER AIRPLANES

Compression damage toPTFE insulation wherewires were in tightcontact

Residue visible on surface - highconcentrations of silver, copper,and sulfur

SULFIDATION IS A SEMICONDUCTIVE DEPOSIT CREATED BY INTERACTION OF SULFUR (CONTAINED IN FUEL) AND EXPOSED SILVER-PLATED COPPER OF WIRES.

BOEING AWARE OF PROBLEM AS A FORM OF CORROSION IN 1980s.

A 1993 BOEING LABORATORY TEST STATED THAT SILVER SHOULD NEVER BE USED IN PRESENCE OF FUEL.

APPEARS AS A LIGHT GREY TO BLACK FILM

PHOTO OF GREY DEPOSITS ON TERMINAL BLOCK WIRES FROM B-747 N93105

Sample From Tower Air B-747 Terminal Block T-347NTSB Sponsored Test by USAF AFRL

(Flash Shown at 100 Volt Pulse of 1.7 millijoules)

Test Probe

Test Probe

SILVER PAINT (connects test probes and surface)

BREAK-DOWN FLASH FRONT

ELECTRICAL BREAK-DOWN OF SULFIDATION(January 13, 1999)(January 13, 1999)(January 13, 1999)(January 13, 1999)

THIS SLIDE IS A PLACE-HOLDER FOR

A 20-SECOND VIDEO CLIP OF BREAKDOWN

SULFIDE-INVOLVED ARC & IGNITION EVENTS

Unknown energy. Flashing dischargesobserved from DC power source of unknownenergy. Subsequent ignition reported from bothDC and AC power.

Samples created inlaboratories at UDRI &ASU.

Unknown Report Number,11/9/99

ARC &IGNITION

Breakdown at about 700 volts. Energy notrecorded.

Laboratory tests tointentional overload.

Boeing 9-5576-WP-97-252,8/5/97

BREAKDOWN

Fuel vapor ignition attempted with badlydamaged remnant of Tower Air terminal strip.

Tower Air(same as above)No ignition

Carbon film breakdown found similar tosulfides and used to ignite lighter fluid in threetests. Minimum (input) energy = 810 mJ.

(Vapor-deposited carbontried during Tower Airtests.)

(same as above)IGNITION

105.3 mJ breakdown (input). Breakdownresulted in loud pop and flashing arc at 2.47 J(input 170 volt pulse). Other breakdowns at10-200 volts.

Tower AirAFRL / MLS 99-68, 10/18/99ARC

Dipping wires in fuel then applying power didnot ignite. (Uncontrolled & informal test)

(same as above)(same as above)No ignition

Report describes as arcing. No energy recordedat film rupture of 13V & 10mA.

USAF Trainer probes inlab

AFRL report of May 1992Breakdown of depositcited as an ARC.

Unrecorded energy from MD-2A tester. Thedischarge melted plastic cap material.

USAF Trainer probe inshop

AFRL report of March 1990IGNITION of fuelvapor

Unrecorded energy from 115 vac system. Fuelpump motor windings molten.

Hydro-Aire fuel pumpsBoeing BMT MS21053,6/17/88

ARC-damage found.unknown ignition

Energy & CommentsSampleLocation & ReportBreakdown, Arc,Ignition?

SULFIDATION & RECOMMENDATION A-98-37

FAA FUNDED RESEARCH WITH STANFORD RESEARCH INSTITUTE, AIR FORCE RESEARCH LABORATORY, UDRI, ARIZONA STATE UNIV, BOEING, & FQIS MANUFACTURERS.

CWT ENVIRONMENT FOUND MOST CONDUCIVE TO FORMATION.

MANUFACTURERS ALREADY FOUND THAT SILVER-SULFIDES MAY BE PREVENTED BY USE OF NICKEL-PLATED FUEL TANK WIRE HARNESSES.

NICKEL-PLATED HARNESSES ARE IN LIMITED PRODUCTION.

Require research into copper-sulfide deposits on fuel quantity indicationsystem parts in fuel tanks to determine the levels of deposits that may behazardous, how to inspect and clean the deposits, and when to replacethe components. (NTSB Recommendation A-98-37, April 7, 1998)

NTSB SAFETY RECOMMENDATIONS

A-98-34 called for : Detailed inspection of FQIS in “Classic” 747 fuel tanks. Result: FAA issued AD’s requiring inspections. (Continuing maintenance is also cited in NPRM 99-18.)

A-98-35 called for : Replacing Honeywell FQIS Series 1-3 terminal blocks. Result: FAA issued AD for removal of terminal blocks.

NTSB SAFETY RECOMMENDATIONS

A-98-36 called for : Survey of other airplane models for potential ignition sources by FQIS and other areas. Result:

FAA initiated inspections,

Over 100 Service Bulletins and AD releases to date.

Aging Transport Systems Rulemaking Advisory Committee (ATSRAC), and

Notice of Proposed Rulemaking (NPRM) 99-18. Flammable vapor protection in new aircraft, Development of FMEA for all transports, New maintenance and inspection standards.

A-98-38 called for : Physical separation and shielding of FQIS wires. Result: ADs issued, but Transient Suppression Devices (TSDs) have been proposed as a substitute.

A-98-39 called for : Transient Suppression Devices (TSD) for FQIS Result: BFGoodrich & Smiths Industries have developed TSD devices to new certification requirement.

Industry position is that 737 and 747 TSDs satisfy both safety recommendations, since:

(1) the energy required for FQIS function will notpermit a hazard to pass, and

(2) TSD failure criteria meet all foreseeableevents (per FAA Advisory Circular 25.1309).

NTSB SAFETY RECOMMENDATIONSNTSB SAFETY RECOMMENDATIONS

INVESTIGATION RESULTS

FAA Aging Transport Non-Structural Systems Plan Maintenance Revisions in Development

Transient Suppression Devices

Change in average fuel tank explosion rate estimated Change in average fuel tank explosion rate estimated by FAA ARAC to go from 1 in 4 years to 1 in 32 years. by FAA ARAC to go from 1 in 4 years to 1 in 32 years. NPRM 99-18 addresses flammable vapor protection in new designs, development of FMEA for all transports, new maintenance and inspection standards.

Over 100 Service Bulletins and AD releases to date.

Fuel Tank ProtectionFuel Tank Protection

Aging of Aircraft SystemsAging of Aircraft Systems

Vulnerable Wire ProtectionVulnerable Wire Protection

More than a hundred people from the followingMore than a hundred people from the followingorganizations were group members and regularorganizations were group members and regular

participants:participants:

AAIB (UK), AEA (UK), ALPA, BEA (France),AAIB (UK), AEA (UK), ALPA, BEA (France),Boeing, Hydro-Boeing, Hydro-AireAire, Lear-, Lear-RomecRomec, Exxon Research,, Exxon Research,

FAA, Goodyear, Hamilton Standard, Honeywell,FAA, Goodyear, Hamilton Standard, Honeywell,IAMAW, Lectromec, Lockheed-Martin, NASA,IAMAW, Lectromec, Lockheed-Martin, NASA, Octel Octel

America, Raytheon, America, Raytheon, TecstarTecstar, TWA, University of, TWA, University ofDayton Research Institute, USAF, US Navy, andDayton Research Institute, USAF, US Navy, and

many others!many others!

THANK YOU TO ALL WHO HELPED!THANK YOU TO ALL WHO HELPED!

INSERT I:\as40\digital_photos\TW800 photos\signature.jpg

INTRODUCE SURVEY OF OTHERAIRPLANES:Shavings poking through bundle,

Poster-children (2) to show shaving andchemical contamination of wire bundle in 747and A300, plus metal washer and lint bridgingcircuit breakers in A300,

NEED TO ORGANIZE FOLLOWING:1998 767 wire fire to show shavings can start fire, (MOVE TOPREFACE LECTROMEC TEST?)Lack of cleanliness (not the mx results shown in previous slide) in areabehind FE station (use several photos to include Douglas and Airbus),1991 L-1011 fire photo shows previous similar findings,747 CWT FQIS bundle chafing on galley cables,Bundles at STA 400 abraded through protective weave on FQIS-typewire set,Fluid stains (may use Boeing SL20-048 photo),Boeing photo of connector grommets next to our photo from pumpconnector,Cracked wire insulation,

TESTING AT LECTROMECIntro that tests examined short circuit properties of Poly-X. Showvideo of about 8-10 minutes.Summary photos of their finding (1) shavings can cut and short wires,but not for long periods, (2) wet-shorts can last for long periods of time,and (3) power / energy.

RAYTHEON MATERIAL TO GO HERE?

OTHER MEANS OF ENERGY ENTRYEMI found not to threaten FQIS, but switching was recorded as CVRdrop-outs

ENERGY RELEASE INSIDE OF TANKCompensator,Breaches found in PTFE insulation from accidentairplane,SulfidesDismiss metal clamps on probe terminal blocks,747s and 757 had chafes similar to those found afterexplosion of Navy C-130Photo of safety wire caught in pump inlet screen,could’ve caught between wires or tubes.Other ideas we looked into (water, etc)

ENERGY ENTRY INTO FQIS AND RELEASEENERGY ENTRY INTO FQIS AND RELEASEFeb 16, 00, Meeting of FAA, NTSB, and Boeing

Wire damage: + Chafe on structure + Wire shield exposed to core (internal or between wires) *+ Mechanical damage (includes mx)+ Debris (Steel wool & drill shavings)*+Sulfidation

POTENTIAL FORENERGY RELEASEFROM FQIS IN TANK:

POTENTIALFOR ENERGYTO ENTER TANK FQIS:

Damaged wires: *+Chafes between wires +Secondary shorts (from other wires shorting) *+Mechanical damage *+Shavings+Water intrusion+Connector shorts+Component failures Inter-tank wires & connections

* Denotes findings in wreckage+ Denotes findings in other airplanes(See also the listing in NPRM 99-18)

CWT Fuel Probe FragmentsCWT Fuel Probe FragmentsCWT Fuel Probe FragmentsCWT Fuel Probe FragmentsRecovered and IdentifiedRecovered and IdentifiedRecovered and IdentifiedRecovered and IdentifiedFrom TWA 800From TWA 800From TWA 800From TWA 800

Honeywell FG420 -A16 -A13 -A13 -A15 -A12 -A12 -A12 -A14Honeywell FG420 -A16 -A13 -A13 -A15 -A12 -A12 -A12 -A14Honeywell FG420 -A16 -A13 -A13 -A15 -A12 -A12 -A12 -A14Honeywell FG420 -A16 -A13 -A13 -A15 -A12 -A12 -A12 -A14NTSB Fragment ID: 72 27 78 53 49 74 59 68NTSB Fragment ID: 72 27 78 53 49 74 59 68NTSB Fragment ID: 72 27 78 53 49 74 59 68NTSB Fragment ID: 72 27 78 53 49 74 59 68

Note : The FG420-12 and -13 probes are interchangeable and the fragments had noidentity as to whether the original locations were on the left or right side of the fuel tank.

FG6Compensatordescriptions

are separate.

Terminal block

-16-13

-15&FG6

-12 -12

-14

(Dry Bay)

Original Installations in CWT:

Recovered wiring& original routing

RightWing

LeftWing

Solid area showsSolid area showsSolid area showsSolid area showsamount recoveredamount recoveredamount recoveredamount recoveredand identified.and identified.and identified.and identified.

Dashed lines showDashed lines showDashed lines showDashed lines showrelative lengths ofrelative lengths ofrelative lengths ofrelative lengths ofthe original probethe original probethe original probethe original probeset.set.set.set.

Scale shown isapproximate.

-13

Rev. 1/19/99

72 inches

36 inches

SULFIDES INVESTIGATIONSULFIDES INVESTIGATIONFeb 16, 00, Meeting of FAA, NTSB, and Boeing

ALLEVIATION TECHNIQUES IDENTIFIED BY FQIS MANUFACTURERS.

LABORATORY INVESTIGATION IN-PROCESS SULFIDES DEVELOPED, SIMILARITIES IN REVIEW. IGNITIONS HAPPENED, VALIDITY IN REVIEW.

REVIEW: IGNITION IN USAF TRAINER PROBE ARCING AND STATOR DAMAGE FOUND IN 1988 FUEL PUMP TEAR-DOWNS. SIMILAR MECHANISM (GLYCOL IGNITION) FOUND AFTER APOLLO-1 FIRE.

TWA 800 FQIS TANK FINDINGS(January 19, 1999)(January 19, 1999)(January 19, 1999)(January 19, 1999)

0.06 inch

Compression damage toPTFE insulation wherewires were in tightcontact

Residue visible on surface - highconcentrations of silver, copper,and sulfur

TERM. BLOCKS DAMAGE WIRES

DAMAGE BETWEENTERM. BLOCK WIRES

DAMAGED WIRESAT

MAINT. ERROR(struc-

ture, wire repair, etc)

COLD FLOW OFINSULATION

METAL DEBRIS

SULFIDATION

COMPENSATOR

DISCHARGE LOCATION IN TANK

0 25 i h

Teflon Wrap

Fiberglass LacingBraid

OR

ACCIDENT AIRPLANE, N93119, WING TANK

B-747 N93105

B-747 N93117

CHAFECHAFE

LOSS OF WIRESEPARATION

Day 2MAINTENANCE AND AGING OF AIRCRAFTSYSTEMS:Chart to show the range of hours for the airplanes weinspected. It shows that many airplanes were inspected andthat they weren’t all retired.Chart to show how often wire-related problems occur.Sample record to show how wire discrepancies are writtenagainst system, not against wiring itself.

DESIGN AND CERTIFICATION: (If Bernie is doing thissection, do I need to prepare it?)

UNDAMAGED AREAS OF AGED POLY-X DID NOT PASS MANUFACTURER SPECIFICATIONS, BUT :

“WOULD BE EXPECTED TO PERFORM ADEQUATELY IN THE SHORT TERM, PROVIDED THERE IS NO ADDED STRESS BEYOND WHAT IT HAS EXPERIENCED.” TESTING OF DAMAGED AREAS WITH WATER, FLUID REACHED THE CONDUCTOR IN ABOUT 1 OUT OF 5 DAMAGED AREAS.

POLY-X FAILED MORE TESTS THAN OTHER TYPES (FOUND IN 1970s to AGE 7X FASTER THAN KAPTON).

(REPORT NOTES THAT ALL WIRES WERE FROM PROTECTED FUSELAGE AREAS.)

RESULTS OF TESTING AGED WIRES RESULTS OF TESTING AGED WIRES (RAYTHEON)(RAYTHEON)

Feb 16, 00, Meeting of FAA, NTSB, and Boeing

INVESTIGATION INTO POSSIBLE IGNITION SOURCES LED TO THREE FOCAL AREAS:

FINDING POTENTIAL IGNITION SOURCES IDENTIFICATION OF AGING SYSTEMS PROTECTION OF VULNERABLE CIRCUITS