Narrative:

Level 2 flap disagree alert at FL400 at mach .82. At the same time the high speed and low speed foot indication on the pfd's closed in on each other as the autothrottles came back. At this time I disconnected autoplt and autothrottles. Selected a speed of M.82 at the same time as the pm requested and received a lower altitude. Prior to the descent the stick shaker activated. I could also feel a controllable but noticeable roll to the right. The configuration display indicated left inboard flap at 29 to 32 degrees. With intermittent stick shaker during descent we declared an emergency and started a left turn southbound with several airports available as potential divert fields. At FL230 and an IAS of 220 KTS the flaps went back to up position; pfd indications normal and no stick shaker. Due to the normal indications at this point I made the decision to continue back to ZZZ where we made an uneventful landing. Since we had earlier declared an emergency the emergency equipment was standing by at the airport. Also both of our jumpseaters (md-11 qual) were of great assistance in trying to find applicable checklists and communicating with flight control.callback conversation with reporter revealed the following information: post flight analysis of the flight data recorder showed that the flap had not actually extended in flight and that a faulty sensor was the cause of the incident. The primary flight display airspeed tape showed overspeed and the automatic throttle retarded while the overspeed warning sounded. While attempting to honor the overspeed warning came back to a point where stick shaker activated. The rolling tendencies that were noted were apparently caused by flying at or near stick shaker.

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Original NASA ASRS Text

Title: MD11 FLT CREW RPTS FLAP DISAGREE WITH DISPLAY SHOWING LEFT INBOARD FLAP EXTENSION WHILE IN CRUISE AT FL400 M.82. DESCENDING WITH INTERMITTENT STICK SHAKER; FLAP DISAGREE DISAPPEARS AT FL230 AND 220 KTS. AN UNEVENTFUL LNDG ENSUES.

Narrative: LEVEL 2 FLAP DISAGREE ALERT AT FL400 AT MACH .82. AT THE SAME TIME THE HIGH SPEED AND LOW SPEED FOOT INDICATION ON THE PFD'S CLOSED IN ON EACH OTHER AS THE AUTOTHROTTLES CAME BACK. AT THIS TIME I DISCONNECTED AUTOPLT AND AUTOTHROTTLES. SELECTED A SPEED OF M.82 AT THE SAME TIME AS THE PM REQUESTED AND RECEIVED A LOWER ALTITUDE. PRIOR TO THE DESCENT THE STICK SHAKER ACTIVATED. I COULD ALSO FEEL A CONTROLLABLE BUT NOTICEABLE ROLL TO THE RIGHT. THE CONFIGURATION DISPLAY INDICATED LEFT INBOARD FLAP AT 29 TO 32 DEGREES. WITH INTERMITTENT STICK SHAKER DURING DESCENT WE DECLARED AN EMERGENCY AND STARTED A LEFT TURN SOUTHBOUND WITH SEVERAL AIRPORTS AVAILABLE AS POTENTIAL DIVERT FIELDS. AT FL230 AND AN IAS OF 220 KTS THE FLAPS WENT BACK TO UP POSITION; PFD INDICATIONS NORMAL AND NO STICK SHAKER. DUE TO THE NORMAL INDICATIONS AT THIS POINT I MADE THE DECISION TO CONTINUE BACK TO ZZZ WHERE WE MADE AN UNEVENTFUL LANDING. SINCE WE HAD EARLIER DECLARED AN EMERGENCY THE EMERGENCY EQUIPMENT WAS STANDING BY AT THE AIRPORT. ALSO BOTH OF OUR JUMPSEATERS (MD-11 QUAL) WERE OF GREAT ASSISTANCE IN TRYING TO FIND APPLICABLE CHECKLISTS AND COMMUNICATING WITH FLT CONTROL.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: POST FLT ANALYSIS OF THE FLT DATA RECORDER SHOWED THAT THE FLAP HAD NOT ACTUALLY EXTENDED IN FLT AND THAT A FAULTY SENSOR WAS THE CAUSE OF THE INCIDENT. THE PRIMARY FLT DISPLAY AIRSPD TAPE SHOWED OVERSPEED AND THE AUTO THROTTLE RETARDED WHILE THE OVERSPEED WARNING SOUNDED. WHILE ATTEMPTING TO HONOR THE OVERSPEED WARNING CAME BACK TO A POINT WHERE STICK SHAKER ACTIVATED. THE ROLLING TENDENCIES THAT WERE NOTED WERE APPARENTLY CAUSED BY FLYING AT OR NEAR STICK SHAKER.

Data retrieved from NASA's ASRS site as of January 2009 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.