Flight crew of an air carrier small transport twin engine turbo propeller aircraft momentarily lost control of the aircraft on takeoff due to the aileron trim tab set all the way to the left.

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Attributes
ACN	242088
Time
Date	199305
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : gcn
State Reference	AZ
Altitude	agl bound lower : 0 agl bound upper : 200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : gcn
Operator	common carrier : air carrier
Make Model Name	Small Transport
Flight Phase	climbout : takeoff climbout : initial ground : holding
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 250 flight time total : 3000 flight time type : 2000
ASRS Report	242088
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical non adherence : far other anomaly other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Right after V1 call aircraft made sharp roll to the left, initial thought was an engine failure. After checking gauges and finding nothing wrong, I looked down to my left and noticed aileron trim was showing a full deflection to the left. The captain also noticed the same. I helped with the controls to level aircraft after which the captain gave over controls to me while he ran the trim back and pulled the circuit breaker. The runway is cut out amongst the trees so after getting everything situated we cleared the trees by about 100-200 ft. The flight continued without further incident. Initial assessment was a runaway trim tab, but it probably would not have returned to center. The next day I remembered that a passenger poked into the cockpit while we were at the hold line inquiring about her head seat. Trim tab is located right at the entrance to cockpit, passenger probably leaned on trim tab actuator (which is a rocker switch) and ran it all the way to left. Situation could have been avoided by either having a cockpit door or by putting a guard over the switch.

Original NASA ASRS Text

Title: FLC OF AN ACR SMT TWIN ENG TURBO PROP ACFT MOMENTARILY LOST CTL OF THE ACFT ON TKOF DUE TO THE AILERON TRIM TAB SET ALL THE WAY TO THE L.

Narrative: RIGHT AFTER V1 CALL ACFT MADE SHARP ROLL TO THE L, INITIAL THOUGHT WAS AN ENG FAILURE. AFTER CHKING GAUGES AND FINDING NOTHING WRONG, I LOOKED DOWN TO MY L AND NOTICED AILERON TRIM WAS SHOWING A FULL DEFLECTION TO THE L. THE CAPT ALSO NOTICED THE SAME. I HELPED WITH THE CTLS TO LEVEL ACFT AFTER WHICH THE CAPT GAVE OVER CTLS TO ME WHILE HE RAN THE TRIM BACK AND PULLED THE CIRCUIT BREAKER. THE RWY IS CUT OUT AMONGST THE TREES SO AFTER GETTING EVERYTHING SITUATED WE CLRED THE TREES BY ABOUT 100-200 FT. THE FLT CONTINUED WITHOUT FURTHER INCIDENT. INITIAL ASSESSMENT WAS A RUNAWAY TRIM TAB, BUT IT PROBABLY WOULD NOT HAVE RETURNED TO CENTER. THE NEXT DAY I REMEMBERED THAT A PAX POKED INTO THE COCKPIT WHILE WE WERE AT THE HOLD LINE INQUIRING ABOUT HER HEAD SEAT. TRIM TAB IS LOCATED RIGHT AT THE ENTRANCE TO COCKPIT, PAX PROBABLY LEANED ON TRIM TAB ACTUATOR (WHICH IS A ROCKER SWITCH) AND RAN IT ALL THE WAY TO L. SIT COULD HAVE BEEN AVOIDED BY EITHER HAVING A COCKPIT DOOR OR BY PUTTING A GUARD OVER THE SWITCH.

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.