B757 crew had yaw damper failure on landing at atl.

Attributes
ACN	480343
Time
Date	200007
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : atl.airport
State Reference	GA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : atl.tower
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 26r other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 13000 flight time type : 2000
ASRS Report	480343
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	other
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Landing atl runway 26R, good WX, light winds. During landing flare, aircraft began slight float, then strong ballooning, coupled with strong uncommanded left yaw and roll, rising up. Corrective inputs applied to flight controls stabilizing -- the aircraft the landing completed. On rollout, noticed yaw damper EICAS message during taxi in, right yaw damper inoperative light. Call-up of EICAS message display showed right yaw damper message. Upon engine shutdown and changeover to ground electric power, all indications disappeared. From pilot perspective, flight like strong increasing performance left quartering headwind windshear, but light steady winds ruled out WX event. Possible explanation: yaw damper commanded rudder causing yaw and subsequent roll left. Right wing sweeping forward operated additional lift causing ballooning effect.

Original NASA ASRS Text

Title: B757 CREW HAD YAW DAMPER FAILURE ON LNDG AT ATL.

Narrative: LNDG ATL RWY 26R, GOOD WX, LIGHT WINDS. DURING LNDG FLARE, ACFT BEGAN SLIGHT FLOAT, THEN STRONG BALLOONING, COUPLED WITH STRONG UNCOMMANDED L YAW AND ROLL, RISING UP. CORRECTIVE INPUTS APPLIED TO FLT CTLS STABILIZING -- THE ACFT THE LNDG COMPLETED. ON ROLLOUT, NOTICED YAW DAMPER EICAS MESSAGE DURING TAXI IN, R YAW DAMPER INOP LIGHT. CALL-UP OF EICAS MESSAGE DISPLAY SHOWED R YAW DAMPER MESSAGE. UPON ENG SHUTDOWN AND CHANGEOVER TO GND ELECTRIC PWR, ALL INDICATIONS DISAPPEARED. FROM PLT PERSPECTIVE, FLT LIKE STRONG INCREASING PERFORMANCE L QUARTERING HEADWIND WINDSHEAR, BUT LIGHT STEADY WINDS RULED OUT WX EVENT. POSSIBLE EXPLANATION: YAW DAMPER COMMANDED RUDDER CAUSING YAW AND SUBSEQUENT ROLL L. R WING SWEEPING FORWARD OPERATED ADDITIONAL LIFT CAUSING BALLOONING EFFECT.

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.