Sudden yaw during takeoff.

Attributes
ACN	315550
Time
Date	199509
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : phx
State Reference	AZ
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	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : takeoff
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : cfi pilot : atp pilot : commercial
Experience	flight time last 90 days : 230 flight time total : 15000 flight time type : 230
ASRS Report	315550
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial
Experience	flight time last 90 days : 210 flight time total : 10000 flight time type : 5600
ASRS Report	315551
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Flight from phx-tus. During takeoff roll in a boeing 737-300 at phx, just prior to V1 (139 KTS), a sharp momentary yaw left occurred with a jolt. Our takeoff was continued and the 'yaw damper non-normal checklist' was complied with. Yaw damper switch was turned to off position. The 'after takeoff checklist' was then complied with as our departure continued. After leveloff at 17000 ft MSL, an evaluation of situation was discussed between cockpit crew. Then maintenance was notified and the discrepancy was entered into the logbook. Quote, 'during takeoff roll at phx just prior to V1 (139 KTS), a sharp, momentary yaw left occurred. Takeoff continued and yaw damper was turned off.' the flight landed in tus with no further occurrences.

Original NASA ASRS Text

Title: SUDDEN YAW DURING TKOF.

Narrative: FLT FROM PHX-TUS. DURING TKOF ROLL IN A BOEING 737-300 AT PHX, JUST PRIOR TO V1 (139 KTS), A SHARP MOMENTARY YAW L OCCURRED WITH A JOLT. OUR TKOF WAS CONTINUED AND THE 'YAW DAMPER NON-NORMAL CHKLIST' WAS COMPLIED WITH. YAW DAMPER SWITCH WAS TURNED TO OFF POS. THE 'AFTER TKOF CHKLIST' WAS THEN COMPLIED WITH AS OUR DEP CONTINUED. AFTER LEVELOFF AT 17000 FT MSL, AN EVALUATION OF SIT WAS DISCUSSED BTWN COCKPIT CREW. THEN MAINT WAS NOTIFIED AND THE DISCREPANCY WAS ENTERED INTO THE LOGBOOK. QUOTE, 'DURING TKOF ROLL AT PHX JUST PRIOR TO V1 (139 KTS), A SHARP, MOMENTARY YAW L OCCURRED. TKOF CONTINUED AND YAW DAMPER WAS TURNED OFF.' THE FLT LANDED IN TUS WITH NO FURTHER OCCURRENCES.

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.