An air carrier mdt aborted its takeoff.

Attributes
ACN	253051
Time
Date	199309
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : hvn
State Reference	CT
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	Medium Transport, High Wing, 2 Turboprop Eng
Navigation In Use	Other Other
Flight Phase	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 215 flight time total : 7684 flight time type : 1005
ASRS Report	253051
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : unable other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

The takeoff warning horn sounded as the power was advanced for takeoff. The crew aborted the takeoff and taxied clear of the runway. All controls were verified to be in the correct position for takeoff using flaps 5 degrees. The crew returned to the gate and reported the maintenance discrepancy to company maintenance operations control center. At the direction of company maintenance operations control center, a local mechanic accompanied us for a runup check during which the flaps were positioned at both 5 degrees and 15 degrees takeoff settings. The takeoff warning horn did not sound with the flaps at either position. The mechanic approved the aircraft for return to service. The warning horn was attributed to either a malfunctioning microswitch or to a 'nuisance trip' of the takeoff warning horn caused by a buildup of tolerances in the flap and takeoff warning system, a situation occasionally present in the mdt aircraft.

Original NASA ASRS Text

Title: AN ACR MDT ABORTED ITS TKOF.

Narrative: THE TKOF WARNING HORN SOUNDED AS THE PWR WAS ADVANCED FOR TKOF. THE CREW ABORTED THE TKOF AND TAXIED CLR OF THE RWY. ALL CTLS WERE VERIFIED TO BE IN THE CORRECT POS FOR TKOF USING FLAPS 5 DEGS. THE CREW RETURNED TO THE GATE AND RPTED THE MAINT DISCREPANCY TO COMPANY MAINT OPS CTL CTR. AT THE DIRECTION OF COMPANY MAINT OPS CTL CTR, A LCL MECH ACCOMPANIED US FOR A RUNUP CHK DURING WHICH THE FLAPS WERE POSITIONED AT BOTH 5 DEGS AND 15 DEGS TKOF SETTINGS. THE TKOF WARNING HORN DID NOT SOUND WITH THE FLAPS AT EITHER POS. THE MECH APPROVED THE ACFT FOR RETURN TO SVC. THE WARNING HORN WAS ATTRIBUTED TO EITHER A MALFUNCTIONING MICROSWITCH OR TO A 'NUISANCE TRIP' OF THE TKOF WARNING HORN CAUSED BY A BUILDUP OF TOLERANCES IN THE FLAP AND TKOF WARNING SYS, A SIT OCCASIONALLY PRESENT IN THE MDT ACFT.

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.