Flight crew lose roll control at FL365 in climb to FL370 and have to descend.

Attributes
ACN	317132
Time
Date	199503
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ztl
State Reference	GA
Altitude	msl bound lower : 36500 msl bound upper : 37000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	enroute airway : ztl
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 15500 flight time type : 3000
ASRS Report	317132
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : regained aircraft control flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Md-80 flight from iah to dca, while climbing to 37000 ft, autoplt, autothrottles, and flight directors kept tripping off, in various combinations at intermittent intervals. At the time of the event, I was hand flying the aircraft, as a result. Upon leaving 36500 ft for 3700 ft, the aircraft began a rapid roll to the left, which I was able to stop at 35 degree of bank and return to level flight. I also felt a severe yaw motion and immediately suspected the yaw damper, which was confirmed by an intermittent illumination of the 'yaw damper off' annunciator. We immediately switched the yaw damper off, moved the rudder power lever to manual, descended to (yaw damper off) maximum altitude, and continued to destination uneventfully. The next morning I found out that technical services discovered a bad yaw rate sensor (gyroscope) and replaced it. Callback conversation with reporter revealed the following information: the reporter said the md-80 weighed, he thought, about 117000 pounds he calculated the maximum gross weight at FL370 to be 118000 that day. He said he thought it was lucky the autoplt had tripped off and he was hand flying the airplane when the yaw rate sensor acted up and the airplane started to roll because he could better control the airplane and counteract the roll and dutch roll tendencies.

Original NASA ASRS Text

Title: FLC LOSE ROLL CTL AT FL365 IN CLB TO FL370 AND HAVE TO DSND.

Narrative: MD-80 FLT FROM IAH TO DCA, WHILE CLBING TO 37000 FT, AUTOPLT, AUTOTHROTTLES, AND FLT DIRECTORS KEPT TRIPPING OFF, IN VARIOUS COMBINATIONS AT INTERMITTENT INTERVALS. AT THE TIME OF THE EVENT, I WAS HAND FLYING THE ACFT, AS A RESULT. UPON LEAVING 36500 FT FOR 3700 FT, THE ACFT BEGAN A RAPID ROLL TO THE L, WHICH I WAS ABLE TO STOP AT 35 DEG OF BANK AND RETURN TO LEVEL FLT. I ALSO FELT A SEVERE YAW MOTION AND IMMEDIATELY SUSPECTED THE YAW DAMPER, WHICH WAS CONFIRMED BY AN INTERMITTENT ILLUMINATION OF THE 'YAW DAMPER OFF' ANNUNCIATOR. WE IMMEDIATELY SWITCHED THE YAW DAMPER OFF, MOVED THE RUDDER PWR LEVER TO MANUAL, DSNDED TO (YAW DAMPER OFF) MAX ALT, AND CONTINUED TO DEST UNEVENTFULLY. THE NEXT MORNING I FOUND OUT THAT TECHNICAL SVCS DISCOVERED A BAD YAW RATE SENSOR (GYROSCOPE) AND REPLACED IT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAID THE MD-80 WEIGHED, HE THOUGHT, ABOUT 117000 LBS HE CALCULATED THE MAX GROSS WT AT FL370 TO BE 118000 THAT DAY. HE SAID HE THOUGHT IT WAS LUCKY THE AUTOPLT HAD TRIPPED OFF AND HE WAS HAND FLYING THE AIRPLANE WHEN THE YAW RATE SENSOR ACTED UP AND THE AIRPLANE STARTED TO ROLL BECAUSE HE COULD BETTER CTL THE AIRPLANE AND COUNTERACT THE ROLL AND DUTCH ROLL TENDENCIES.

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.