B737-300 experiences flap asymmetry which goes away after recycling.

Attributes
ACN	692634
Time
Date	200604
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : sea.airport
State Reference	WA
Altitude	msl single value : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : sea.tower
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 180 flight time total : 8500 flight time type : 2800
ASRS Report	692634
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical other anomaly
Independent Detector	aircraft equipment other aircraft equipment : flap position ind/stall warning other flight crewa other flight crewb
Resolutory Action	aircraft : equipment problem dissipated flight crew : overcame equipment problem
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

On a visual approach into sea; our trailing edge flaps failed to deploy because of asymmetry. We were on a base leg to runway 16R at 3000 ft and 210 KTS. Approach asked us to slow to 170 KTS to follow traffic which we had in sight. The first officer was flying and asked for flaps 5 degrees; and then flaps 10 degrees for 170 KTS. The aircraft was decelerating slowly so I asked for landing gear down and flaps 15 degrees so that we would not be high. At about 2000 ft AGL we were still high so I asked for flaps 30 degrees at 165 KTS. I noticed a very high deck angle for flaps 30 degrees. The captain noticed the stall warning indicator on the HUD was within 10-15 KTS. We both looked at the flap indicator and noticed the left trailing edge flap at 1/2 and the right trailing edge flap at 1 degree position. The leading edge slats were fully out and the leading edge flaps were in the intermediate position. The first officer executed the go around and we cleaned the aircraft up to flaps 1 degree. The captain performed the trailing edge flaps asymmetrical checklist. We positioned the flap lever up; in accordance with the checklists. The flaps stayed the same. We started getting prepared for landing. The captain did the performance in the opc and we set our bugs accordingly. We then noticed both flap indicators had gone to the zero position and the leading edge devices were fully retracted. After discussion; we decided to test the flaps and see if they would work correctly this time. We tried flaps 1 degree; then 2 degrees; then 5 degrees and everything was working normally. We decided to land with flaps 15 degrees. The approach and landing were normal. During the taxi in; we retracted the flaps and then cycled them to 30 degrees and back to 0 degrees. Everything was normal. At the gate; we called dispatch and maintenance control and they decided to have contract maintenance come inspect the flaps. I always check the flap indicator when flaps are called on a checklist. I need to make it a habit to always check the indicator every time the flap handle is moved.

Original NASA ASRS Text

Title: B737-300 EXPERIENCES FLAP ASYMMETRY WHICH GOES AWAY AFTER RECYCLING.

Narrative: ON A VISUAL APCH INTO SEA; OUR TRAILING EDGE FLAPS FAILED TO DEPLOY BECAUSE OF ASYMMETRY. WE WERE ON A BASE LEG TO RWY 16R AT 3000 FT AND 210 KTS. APCH ASKED US TO SLOW TO 170 KTS TO FOLLOW TFC WHICH WE HAD IN SIGHT. THE FO WAS FLYING AND ASKED FOR FLAPS 5 DEGS; AND THEN FLAPS 10 DEGS FOR 170 KTS. THE ACFT WAS DECELERATING SLOWLY SO I ASKED FOR LNDG GEAR DOWN AND FLAPS 15 DEGS SO THAT WE WOULD NOT BE HIGH. AT ABOUT 2000 FT AGL WE WERE STILL HIGH SO I ASKED FOR FLAPS 30 DEGS AT 165 KTS. I NOTICED A VERY HIGH DECK ANGLE FOR FLAPS 30 DEGS. THE CAPT NOTICED THE STALL WARNING INDICATOR ON THE HUD WAS WITHIN 10-15 KTS. WE BOTH LOOKED AT THE FLAP INDICATOR AND NOTICED THE L TRAILING EDGE FLAP AT 1/2 AND THE R TRAILING EDGE FLAP AT 1 DEG POS. THE LEADING EDGE SLATS WERE FULLY OUT AND THE LEADING EDGE FLAPS WERE IN THE INTERMEDIATE POS. THE FO EXECUTED THE GAR AND WE CLEANED THE ACFT UP TO FLAPS 1 DEG. THE CAPT PERFORMED THE TRAILING EDGE FLAPS ASYMMETRICAL CHKLIST. WE POSITIONED THE FLAP LEVER UP; IN ACCORDANCE WITH THE CHKLISTS. THE FLAPS STAYED THE SAME. WE STARTED GETTING PREPARED FOR LNDG. THE CAPT DID THE PERFORMANCE IN THE OPC AND WE SET OUR BUGS ACCORDINGLY. WE THEN NOTICED BOTH FLAP INDICATORS HAD GONE TO THE ZERO POS AND THE LEADING EDGE DEVICES WERE FULLY RETRACTED. AFTER DISCUSSION; WE DECIDED TO TEST THE FLAPS AND SEE IF THEY WOULD WORK CORRECTLY THIS TIME. WE TRIED FLAPS 1 DEG; THEN 2 DEGS; THEN 5 DEGS AND EVERYTHING WAS WORKING NORMALLY. WE DECIDED TO LAND WITH FLAPS 15 DEGS. THE APCH AND LNDG WERE NORMAL. DURING THE TAXI IN; WE RETRACTED THE FLAPS AND THEN CYCLED THEM TO 30 DEGS AND BACK TO 0 DEGS. EVERYTHING WAS NORMAL. AT THE GATE; WE CALLED DISPATCH AND MAINT CTL AND THEY DECIDED TO HAVE CONTRACT MAINT COME INSPECT THE FLAPS. I ALWAYS CHK THE FLAP INDICATOR WHEN FLAPS ARE CALLED ON A CHKLIST. I NEED TO MAKE IT A HABIT TO ALWAYS CHK THE INDICATOR EVERY TIME THE FLAP HANDLE IS MOVED.

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.