Flight crew of medium large transport has split flap indication on approach. A go around was made an...

Attributes
ACN	370674
Time
Date	199706
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lax
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : lax
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach landing : go around
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 25100 flight time type : 500
ASRS Report	370674
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

A go around at lax for runway 25R due to a split flap indication on final approach. Right flap indication was 15 degrees and left flap needle indicated about 23-25 degrees. There was no roll control problem or displaced aileron control. I suspected only an indicator malfunction, but it did cause flap movement to stop. A momentary movement of the alternate flap switch realigned the needles and normal flap movement was restored via normal flap handle selection. A normal 30 degree flap landing was made. However, the book procedure would have been to land with a split flap indication and thus not in a normal landing flap confign. I felt that as I stated that this was probably not a true split flap and therefore just an indicator problem that stopped flap movement. The asymmetry switch for the flap protection is in the flap gauge. By using the alternate flap extension, I bypassed the asymmetry switch momentarily enough to get things moving again and as this is not a published procedure, I therefore used captain's emergency authority/authorized to produce the desired results, and eliminated the highest landing speed of vref 40 degree flaps plus 40 KTS.

Original NASA ASRS Text

Title: FLC OF MLG HAS SPLIT FLAP INDICATION ON APCH. A GAR WAS MADE AND DETERMINATION THAT THE INDICATOR WAS THE PROB, NOT THE FLAPS SINCE NO ROLL CTL DEVELOPED. ABLE TO CORRECT TO NORMAL FLAP MOVEMENT AND LAND.

Narrative: A GAR AT LAX FOR RWY 25R DUE TO A SPLIT FLAP INDICATION ON FINAL APCH. R FLAP INDICATION WAS 15 DEGS AND L FLAP NEEDLE INDICATED ABOUT 23-25 DEGS. THERE WAS NO ROLL CTL PROB OR DISPLACED AILERON CTL. I SUSPECTED ONLY AN INDICATOR MALFUNCTION, BUT IT DID CAUSE FLAP MOVEMENT TO STOP. A MOMENTARY MOVEMENT OF THE ALTERNATE FLAP SWITCH REALIGNED THE NEEDLES AND NORMAL FLAP MOVEMENT WAS RESTORED VIA NORMAL FLAP HANDLE SELECTION. A NORMAL 30 DEG FLAP LNDG WAS MADE. HOWEVER, THE BOOK PROC WOULD HAVE BEEN TO LAND WITH A SPLIT FLAP INDICATION AND THUS NOT IN A NORMAL LNDG FLAP CONFIGN. I FELT THAT AS I STATED THAT THIS WAS PROBABLY NOT A TRUE SPLIT FLAP AND THEREFORE JUST AN INDICATOR PROB THAT STOPPED FLAP MOVEMENT. THE ASYMMETRY SWITCH FOR THE FLAP PROTECTION IS IN THE FLAP GAUGE. BY USING THE ALTERNATE FLAP EXTENSION, I BYPASSED THE ASYMMETRY SWITCH MOMENTARILY ENOUGH TO GET THINGS MOVING AGAIN AND AS THIS IS NOT A PUBLISHED PROC, I THEREFORE USED CAPT'S EMER AUTH TO PRODUCE THE DESIRED RESULTS, AND ELIMINATED THE HIGHEST LNDG SPD OF VREF 40 DEG FLAPS PLUS 40 KTS.

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.

Flight crew of medium large transport has split flap indication on approach. A go around was made and determination that the indicator was the problem, not the flaps since no roll control developed. Able to correct to normal flap movement and land.