A B737-200 WAS ON APCH AT 2000 FT; WITH FLAPS SELECTED TO 30 UNITS; WHEN CREW HEARD A SNAPPING SOUND. THE AIRPLANE THEN BEGAN A SLOW UNCOMMANDED R ROLL.

Narrative

A SNAPPING SOUND WAS HEARD WHEN TRANSITIONING TO FLAPS 30; AND THE ACFT BEGAN AN UNCOMMANDED SLOW ROLL TO THE R. THE VISUAL APCH TO RWY 26 WAS ABORTED IN FAVOR OF RWY 17R. NO ASYMMETRICAL GAUGE OR LED INDICATIONS NOTED. VREF 15 SPEEDS WERE FLOWN TO A NORMAL TOUCHDOWN AND LNDG ON 17R. 45 DEG OF YOKE DISPLACEMENT REQUIRED FOR WINGS LEVEL FLT. NO VIBRATIONS NOTED. CALLBACK CONVERSATION WITH RPTR REVEALED FOLLOWING INFO: THE RPTR STATED THE FLT CREW HEARD A SNAPPING SOUND WHEN FLAPS WERE SELECTED FROM 15 UNITS TO 30 UNITS; AND NOTED AN UNCOMMANDED ROLL TO THE R. THE RPTR SAID THE ROLL REQUIRED 45 DEG OF YOKE INPUT TO LEVEL THE AIRPLANE AND 25 DEGS YOKE INPUT TO MAINTAIN LEVEL FLT. THE RPTR STATED THAT APPROX ONE YEAR PRIOR TO THIS INCIDENT; THE RPTR EXPERIENCED AN OUTBOARD FLAP CARRIAGE SPINDLE FAILURE AND THE AIRPLANE PERFORMANCE WAS IDENTICAL TO THIS INCIDENT. THE RPTR SAID THERE WAS NO FLAP ASYMMETRICAL SHUTOFF OR POSITION INDICATION ON THE TRAILING EDGE AND LEADING EDGE DEVICES. THE RPTR STATED THE DAILY CHECK REQUIRED BY THE AIRWORTHINESS DIRECTIVE WAS PERFORMED IN THE MORNING PRIOR TO DEP AND WAS SIGNED OFF. THE RPTR SAID THE MANUFACTURER WILL NOT ALLOW ANY MACHINE WORK ON THE SPINDLE; AND MUST BE REPLACED WITH A NEW UNIT. THE RPTR STATED THAT ON THE GND MAINT FOUND THE L OUTBOARD MID FLAP SPINDLE SHEARED.