Uncommanded autoplt roll.

Attributes
ACN	312266
Time
Date	199508
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : clt
State Reference	NC
Altitude	msl bound lower : 12000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : clt
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : private pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 6000 flight time type : 1000
ASRS Report	312266
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : regained aircraft control
Consequence	faa : reviewed incident with flight crew Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On arrival into clt, nc, with autoplt engaged in 'a' channel, aircraft suddenly shuddered and began a rapid, uncommanded roll to the left. The captain disconnected the autoplt and arrested roll using nearly full right control wheel. Aircraft was descending through 12000 ft at 250 KTS with autoplt in 'LNAV' and 'level change.' flight conditions were clear and smooth. Nearest aircraft was B737, 7 or 8 mi ahead. Remainder of flight was normal. Callback conversation with reporter revealed the following information: the reporter flies the B737-300 for a united states air carrier. He believes that the autoplt commanded a roll by the spoiler as there was a shudder similar to raising the spoilers with flaps extended. Unfortunately, the reporter did not follow up on the maintenance action taken to correct the aircraft. This incident was written up in the logbook, and the aircraft was taken OTS for some time. The crew worked well together. The reporter reached for the yoke but backed off as he could see that the captain was taking control from the autoplt. The reporter believes that the captain was on the phone with their air carrier several times throughout the next several days. The reporter had never seen the B737 roll at this rate. Had the captain not taken the aircraft quickly, the aircraft might have gotten into real trouble. The captain called ARTCC regarding any other traffic ahead that might have caused wake turbulence immediately after the recovery. There was none.

Original NASA ASRS Text

Title: UNCOMMANDED AUTOPLT ROLL.

Narrative: ON ARR INTO CLT, NC, WITH AUTOPLT ENGAGED IN 'A' CHANNEL, ACFT SUDDENLY SHUDDERED AND BEGAN A RAPID, UNCOMMANDED ROLL TO THE L. THE CAPT DISCONNECTED THE AUTOPLT AND ARRESTED ROLL USING NEARLY FULL R CTL WHEEL. ACFT WAS DSNDING THROUGH 12000 FT AT 250 KTS WITH AUTOPLT IN 'LNAV' AND 'LEVEL CHANGE.' FLT CONDITIONS WERE CLR AND SMOOTH. NEAREST ACFT WAS B737, 7 OR 8 MI AHEAD. REMAINDER OF FLT WAS NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE B737-300 FOR A UNITED STATES ACR. HE BELIEVES THAT THE AUTOPLT COMMANDED A ROLL BY THE SPOILER AS THERE WAS A SHUDDER SIMILAR TO RAISING THE SPOILERS WITH FLAPS EXTENDED. UNFORTUNATELY, THE RPTR DID NOT FOLLOW UP ON THE MAINT ACTION TAKEN TO CORRECT THE ACFT. THIS INCIDENT WAS WRITTEN UP IN THE LOGBOOK, AND THE ACFT WAS TAKEN OTS FOR SOME TIME. THE CREW WORKED WELL TOGETHER. THE RPTR REACHED FOR THE YOKE BUT BACKED OFF AS HE COULD SEE THAT THE CAPT WAS TAKING CTL FROM THE AUTOPLT. THE RPTR BELIEVES THAT THE CAPT WAS ON THE PHONE WITH THEIR ACR SEVERAL TIMES THROUGHOUT THE NEXT SEVERAL DAYS. THE RPTR HAD NEVER SEEN THE B737 ROLL AT THIS RATE. HAD THE CAPT NOT TAKEN THE ACFT QUICKLY, THE ACFT MIGHT HAVE GOTTEN INTO REAL TROUBLE. THE CAPT CALLED ARTCC REGARDING ANY OTHER TFC AHEAD THAT MIGHT HAVE CAUSED WAKE TURB IMMEDIATELY AFTER THE RECOVERY. THERE WAS NONE.

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.