An air carrier medium large transport experienced violent yawing.

Attributes
ACN	272537
Time
Date	199405
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bld airport : las
State Reference	NV
Altitude	msl bound lower : 31000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla tower : bwi
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 23000 flight time type : 5000
ASRS Report	272537
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 7000 flight time type : 4000
ASRS Report	272126
Events
Anomaly	aircraft equipment problem : critical other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

During climb to 31000 ft air frame oscillations occurred at 300 KTS indicated. Speed was reduced and shaking stopped. At cruise, at approximately 70 mach, shaking of the air frame from side to side resumed. Speed was reduced and oscillations ceased again. Minutes later (5?), aircraft experienced a hardover to the right. Autoplt was disconnected and emergency declared. Uneventful descent and landing made.

Original NASA ASRS Text

Title: AN ACR MLG EXPERIENCED VIOLENT YAWING.

Narrative: DURING CLB TO 31000 FT AIR FRAME OSCILLATIONS OCCURRED AT 300 KTS INDICATED. SPD WAS REDUCED AND SHAKING STOPPED. AT CRUISE, AT APPROX 70 MACH, SHAKING OF THE AIR FRAME FROM SIDE TO SIDE RESUMED. SPD WAS REDUCED AND OSCILLATIONS CEASED AGAIN. MINUTES LATER (5?), ACFT EXPERIENCED A HARDOVER TO THE R. AUTOPLT WAS DISCONNECTED AND EMER DECLARED. UNEVENTFUL DSCNT AND LNDG MADE.

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.