Air carrier large transport aborted takeoff when warning horn activated at 80 KTS.

Attributes
ACN	99288
Time
Date	198811
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : msp
State Reference	MN
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : takeoff other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 250 flight time total : 6000 flight time type : 1000
ASRS Report	99288
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 202 flight time total : 9200 flight time type : 5800
ASRS Report	99382
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : overcame equipment problem flight crew : rejected takeoff
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

Aircraft was deiced between XA50 and XB05 local. Departed gate at XB14 local and taxied to runway (approximately 5-6 min taxi). Lowered flaps to 5 degrees and checked takeoff warning horn operation with bypass and speedbrake per our (airlines) normal procedure. While taking runway for takeoff, warning horn sounded as initial spool up power was applied. Flap position was double checked at 5 degrees, speed brake was checked in full forward detent, and trim was checked in takeoff green band. All indications were normal and correct with warning horn still sounding. Flaps were moved to 15 degrees and warning horn stopped. Flaps were moved back to 5 degrees with no resultant horn. While accomplishing all the above, the aircraft had been positioned at a position and hold on the runway and power reduced to idle. Takeoff power was now applied (flaps 5 degrees) and takeoff roll commenced with no horn. At approximately 80 KTS airspeed, takeoff warning horn again sounded. Takeoff was immediately aborted and aircraft was taxied to an adjacent taxiway. Flaps were positioned to 15 degrees and throttles again advanced with no horn. Aircraft reconfigured (flaps and trim) for 15 degree flap takeoff. During 15 degree flap takeoff, no takeoff warning horn was experienced. When aircraft arrived in houston, entire flap position warning system was checked by maintenance. No defects were found and system checked normally. Suspect deice fluid may have contributed to malfunction by entering cannon plug or microswitch in 5 degree flap position sensing system. All procedures and actions taken by crew were per published procedures.

Original NASA ASRS Text

Title: ACR LGT ABORTED TKOF WHEN WARNING HORN ACTIVATED AT 80 KTS.

Narrative: ACFT WAS DEICED BTWN XA50 AND XB05 LCL. DEPARTED GATE AT XB14 LCL AND TAXIED TO RWY (APPROX 5-6 MIN TAXI). LOWERED FLAPS TO 5 DEGS AND CHKED TKOF WARNING HORN OPERATION WITH BYPASS AND SPEEDBRAKE PER OUR (AIRLINES) NORMAL PROC. WHILE TAKING RWY FOR TKOF, WARNING HORN SOUNDED AS INITIAL SPOOL UP PWR WAS APPLIED. FLAP POS WAS DOUBLE CHKED AT 5 DEGS, SPD BRAKE WAS CHKED IN FULL FORWARD DETENT, AND TRIM WAS CHKED IN TKOF GREEN BAND. ALL INDICATIONS WERE NORMAL AND CORRECT WITH WARNING HORN STILL SOUNDING. FLAPS WERE MOVED TO 15 DEGS AND WARNING HORN STOPPED. FLAPS WERE MOVED BACK TO 5 DEGS WITH NO RESULTANT HORN. WHILE ACCOMPLISHING ALL THE ABOVE, THE ACFT HAD BEEN POSITIONED AT A POS AND HOLD ON THE RWY AND PWR REDUCED TO IDLE. TKOF PWR WAS NOW APPLIED (FLAPS 5 DEGS) AND TKOF ROLL COMMENCED WITH NO HORN. AT APPROX 80 KTS AIRSPD, TKOF WARNING HORN AGAIN SOUNDED. TKOF WAS IMMEDIATELY ABORTED AND ACFT WAS TAXIED TO AN ADJACENT TXWY. FLAPS WERE POSITIONED TO 15 DEGS AND THROTTLES AGAIN ADVANCED WITH NO HORN. ACFT RECONFIGURED (FLAPS AND TRIM) FOR 15 DEG FLAP TKOF. DURING 15 DEG FLAP TKOF, NO TKOF WARNING HORN WAS EXPERIENCED. WHEN ACFT ARRIVED IN HOUSTON, ENTIRE FLAP POS WARNING SYS WAS CHKED BY MAINT. NO DEFECTS WERE FOUND AND SYS CHKED NORMALLY. SUSPECT DEICE FLUID MAY HAVE CONTRIBUTED TO MALFUNCTION BY ENTERING CANNON PLUG OR MICROSWITCH IN 5 DEG FLAP POS SENSING SYS. ALL PROCS AND ACTIONS TAKEN BY CREW WERE PER PUBLISHED PROCS.

Data retrieved from NASA's ASRS site as of August 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.