Flight crew of B737 reports un-commanded leading edge device extension at FL400.

Attributes
ACN	804558
Time
Date	200809
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : zzz
State Reference	US
Altitude	msl single value : 40000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	B737-600 -700 -800
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	804558
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	804557
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : le flap transit light other flight crewa
Resolutory Action	controller : issued new clearance flight crew : overcame equipment problem
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Ambiguous

Narrative:

Reaching cruise at FL400; we experienced an un-commanded leading edge device extension at 244 KTS. The aircraft buffeted as though it was in high speed buffet even though it was 10 below barber pole. I noticed that the le flaps transit light was illuminated [and]; looked up at the leading edge device annunciator to see all leading edge device in transit. I called 'flaps' the captain confirmed that the flap handle was in the 0/flap up position; as he did so the leading edge device retracted. We descended to a lower altitude advised ATC of that our maximum speed was 240 KTS and continued to destination.callback conversation with reporter revealed the following information: almost 30 minutes elapsed from the time the flaps were retracted after takeoff and the un-commanded extension at FL400. The flap handle appeared up and did not seem to move when pressure was applied by the captain but the leading edge device retracted. Foqa data indicates that the leading edge device extension was commanded and occurred at 230 KTS. No maintenance action was performed to determine if a fault may exist with the flap handle or flap extension system.

Original NASA ASRS Text

Title: FLT CREW OF B737 RPTS UN-COMMANDED LEADING EDGE DEVICE EXTENSION AT FL400.

Narrative: REACHING CRUISE AT FL400; WE EXPERIENCED AN UN-COMMANDED LEADING EDGE DEVICE EXTENSION AT 244 KTS. THE ACFT BUFFETED AS THOUGH IT WAS IN HIGH SPEED BUFFET EVEN THOUGH IT WAS 10 BELOW BARBER POLE. I NOTICED THAT THE LE FLAPS TRANSIT LIGHT WAS ILLUMINATED [AND]; LOOKED UP AT THE LEADING EDGE DEVICE ANNUNCIATOR TO SEE ALL LEADING EDGE DEVICE IN TRANSIT. I CALLED 'FLAPS' THE CAPT CONFIRMED THAT THE FLAP HANDLE WAS IN THE 0/FLAP UP POSITION; AS HE DID SO THE LEADING EDGE DEVICE RETRACTED. WE DSNDED TO A LOWER ALTITUDE ADVISED ATC OF THAT OUR MAX SPEED WAS 240 KTS AND CONTINUED TO DEST.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: ALMOST 30 MINUTES ELAPSED FROM THE TIME THE FLAPS WERE RETRACTED AFTER TKOF AND THE UN-COMMANDED EXTENSION AT FL400. THE FLAP HANDLE APPEARED UP AND DID NOT SEEM TO MOVE WHEN PRESSURE WAS APPLIED BY THE CAPT BUT THE LEADING EDGE DEVICE RETRACTED. FOQA DATA INDICATES THAT THE LEADING EDGE DEVICE EXTENSION WAS COMMANDED AND OCCURRED AT 230 KTS. NO MAINT ACTION WAS PERFORMED TO DETERMINE IF A FAULT MAY EXIST WITH THE FLAP HANDLE OR FLAP EXTENSION SYSTEM.

Data retrieved from NASA's ASRS site as of May 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.