A B737 on takeoff roll rejected the takeoff at 55 KTS due to takeoff warning horn sounding caused by...

Attributes
ACN	463369
Time
Date	200002
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : iah.airport
State Reference	TX
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : iah.tower
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	ground : takeoff roll
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 100 flight time total : 13000 flight time type : 100
ASRS Report	463369
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi pilot : flight engineer pilot : multi engine
Experience	flight time last 90 days : 197 flight time total : 8542 flight time type : 1075
ASRS Report	463373
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : tkof warning horn other other : slap position indication
Resolutory Action	flight crew : rejected takeoff
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

Throttles advanced for takeoff to takeoff warning horn setting just prior to engaging toga button. Takeoff warning horn sounded. Reduced power just below horn level and hit speed brake handle to insure full retraction. Advanced throttles and horn resounded. Takeoff rejected. Exited runway at highspd. Aircraft parked and rejected takeoff checklist completed. Analysis of problem resulted in notice that green leading edge device extended light extinguished. No lights on overhead. Test of lights indicated leading edge devices retracted. Same were visually extended at flaps 5 degree position. Retracted flaps to zero. No amber in-transit light or overhead indications of transit. Re-extended flaps to 5 degrees with no leading edge device indications. Tested all lamps ok, checked circuit breaker panel and found no breakers popped. Flap position and green leading edge device extended light had been verified by both pilots on taxi out as part of taxi checklist. Contacted station and maintenance and returned to gate. After return to the gate, maintenance tried twice with same result both before and after pushing on all rows of circuit breakers. Suddenly, the flap position indicators cycled toward zero and back to 5 degrees with no handle movement. Immediately, proper leading edge device indications appeared. Test of takeoff warning system was normal for confign - flaps 5 degrees (no horn). Flaps were cycled and takeoff warning system tested several times with normal operating results. Maintenance cleared logbook and flight continued without incident.

Original NASA ASRS Text

Title: A B737 ON TKOF ROLL REJECTED THE TKOF AT 55 KTS DUE TO TKOF WARNING HORN SOUNDING CAUSED BY MALFUNCTIONING LEADING EDGE SLAT POS INDICATIONS.

Narrative: THROTTLES ADVANCED FOR TKOF TO TKOF WARNING HORN SETTING JUST PRIOR TO ENGAGING TOGA BUTTON. TKOF WARNING HORN SOUNDED. REDUCED PWR JUST BELOW HORN LEVEL AND HIT SPD BRAKE HANDLE TO INSURE FULL RETRACTION. ADVANCED THROTTLES AND HORN RESOUNDED. TKOF REJECTED. EXITED RWY AT HIGHSPD. ACFT PARKED AND REJECTED TKOF CHKLIST COMPLETED. ANALYSIS OF PROB RESULTED IN NOTICE THAT GREEN LEADING EDGE DEVICE EXTENDED LIGHT EXTINGUISHED. NO LIGHTS ON OVERHEAD. TEST OF LIGHTS INDICATED LEADING EDGE DEVICES RETRACTED. SAME WERE VISUALLY EXTENDED AT FLAPS 5 DEG POS. RETRACTED FLAPS TO ZERO. NO AMBER IN-TRANSIT LIGHT OR OVERHEAD INDICATIONS OF TRANSIT. RE-EXTENDED FLAPS TO 5 DEGS WITH NO LEADING EDGE DEVICE INDICATIONS. TESTED ALL LAMPS OK, CHKED CIRCUIT BREAKER PANEL AND FOUND NO BREAKERS POPPED. FLAP POS AND GREEN LEADING EDGE DEVICE EXTENDED LIGHT HAD BEEN VERIFIED BY BOTH PLTS ON TAXI OUT AS PART OF TAXI CHKLIST. CONTACTED STATION AND MAINT AND RETURNED TO GATE. AFTER RETURN TO THE GATE, MAINT TRIED TWICE WITH SAME RESULT BOTH BEFORE AND AFTER PUSHING ON ALL ROWS OF CIRCUIT BREAKERS. SUDDENLY, THE FLAP POS INDICATORS CYCLED TOWARD ZERO AND BACK TO 5 DEGS WITH NO HANDLE MOVEMENT. IMMEDIATELY, PROPER LEADING EDGE DEVICE INDICATIONS APPEARED. TEST OF TKOF WARNING SYS WAS NORMAL FOR CONFIGN - FLAPS 5 DEGS (NO HORN). FLAPS WERE CYCLED AND TKOF WARNING SYS TESTED SEVERAL TIMES WITH NORMAL OPERATING RESULTS. MAINT CLRED LOGBOOK AND FLT CONTINUED WITHOUT INCIDENT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A B737 on takeoff roll rejected the takeoff at 55 KTS due to takeoff warning horn sounding caused by malfunctioning leading edge slat position indications.