A300 captain reports number two autopilot rolling the aircraft 20 degrees right before disengaging a...

Narrative:

In cruise at FL320; M.80;light chop; aircraft rolled about 20 degrees right and #2 autopilot disengaged simultaneously. First officer was pilot flying and he reported that he felt right rudder move about 2' in at start of event. He took control of aircraft as I commanded him to do so. He rolled aircraft level and back on altitude and I said; only use #1 a/P now; and guard the controls. Prior to this flight; I had seen a similar log entry 3 days prior. A subsequent crew had accomplished a successful autoland and the aircraft was in CAT IIIB status (aircraft & a/p's). Obviously; whatever maintenance was done was not sufficient to correct the problem. Further research indicates a 30-day history of #2 autopilot problems (failure to engage) and MEL's to return aircraft to service. It is a good thing this event happened to me @ FL320; and not to the crew doing the autoland @ 100ft AGL! I filed a flight safety report with my company and suggested that this aircraft be grounded until the necessary troubleshooting of appropriate systems is accomplished to actually fix the problem. From the log; maintenance has already put an MEL on #2 autopilot and returned this aircraft to service. I don't think that is a safe decision.

Original NASA ASRS Text

Title: A300 Captain reports number two autopilot rolling the aircraft 20 degrees right before disengaging at FL320. This autopilot had a history of maintenance log write-ups but was fully operational at the time of the incident.

Narrative: In cruise at FL320; M.80;light chop; aircraft rolled about 20 degrees right and #2 autopilot disengaged simultaneously. First Officer was pilot flying and he reported that he felt right rudder move about 2' in at start of event. He took control of aircraft as I commanded him to do so. He rolled aircraft level and back on altitude and I said; only use #1 A/P now; and guard the controls. Prior to this flight; I had seen a similar log entry 3 days prior. A subsequent crew had accomplished a successful Autoland and the aircraft was in CAT IIIB status (aircraft & a/p's). Obviously; whatever maintenance was done was not sufficient to correct the problem. Further research indicates a 30-day history of #2 autopilot problems (failure to engage) and MEL's to return aircraft to service. It is a good thing this event happened to me @ FL320; and not to the crew doing the Autoland @ 100ft AGL! I filed a flight safety report with my company and suggested that this aircraft be grounded until the necessary troubleshooting of appropriate systems is accomplished to actually fix the problem. From the log; maintenance has already put an MEL on #2 autopilot and returned this aircraft to service. I don't think that is a safe decision.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	857888
Time
Date	200910
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	A300
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 55 Flight Crew Total 15000 Flight Crew Type 2500
Events
Anomaly	Aircraft Equipment Problem Critical

A300 captain reports number two autopilot rolling the aircraft 20 degrees right before disengaging at FL320. This autopilot had a history of maintenance log write-ups but was fully operational at the time of the incident.