Narrative:

Approaching bna runway 2C, 2100 ft MSL (1500 ft AGL), 153 KIAS, gear down, flaps 15 degrees, autoplt engaged, we selected flaps 30 degrees. As the flaps extended, we heard a 'thud' similar to a nose gear extending hard. There were no other abnormalities. #2 engine was responding to thrust changes slower than #1, so I was noticing yaw and roll associated with my fine tuning of the thrust. At one point after disengaging the autoplt, I did have to make a slight (10-15 degree), momentary left yoke input. 1 of my 2 jump seaters mentioned spindle failure, but I dismissed it immediately because, 1) there was absolutely no unusual roll or yaw, and 2) I was not aware of any company B-300 aircraft experiencing spindle failures. I therefore did not perform the suspected flap spindle failure procedure. We landed uneventfully. After landing, the jump seater informed me we had experienced B-300 spindle failures. As a precaution, we called maintenance and described the problem. They did find a broken spindle on the right wing. Supplemental information from acn 625178: we all wondered what the sound was. (We had 2 cockpit jump seaters.) the captain thought it sounded like a late gear deploy. The jump seaters and I didn't think so, since we had been showing 3 green well before the pop. We mentioned spindle failure, but discounted since there was no roll-off. Thought it was probably a bird and we would make sure the on-coming crew did a good inspection. Taxiing in we discussed what the noise could be. After discussing, we agreed it sounded more mechanical than bird strikes we had experienced in past. We didn't think spindles were as big of an issue in the B-300 as opposed to the B-200, but knew it could happen. One observer had just returned from training and said that company had a few spindle failures in B-300. Maintenance did a spindle check, and discovered the right outboard spindle broken.

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Original NASA ASRS Text

Title: A B737-300 FLT CREW, ON APCH, SELECTED FLAPS 30 DEGS THEN HEARD A 'THUD.' LNDG WAS NORMAL. MAINT INSPECTION REVEALED R OUTBOARD FLAP SPINDLE FAILED.

Narrative: APCHING BNA RWY 2C, 2100 FT MSL (1500 FT AGL), 153 KIAS, GEAR DOWN, FLAPS 15 DEGS, AUTOPLT ENGAGED, WE SELECTED FLAPS 30 DEGS. AS THE FLAPS EXTENDED, WE HEARD A 'THUD' SIMILAR TO A NOSE GEAR EXTENDING HARD. THERE WERE NO OTHER ABNORMALITIES. #2 ENG WAS RESPONDING TO THRUST CHANGES SLOWER THAN #1, SO I WAS NOTICING YAW AND ROLL ASSOCIATED WITH MY FINE TUNING OF THE THRUST. AT ONE POINT AFTER DISENGAGING THE AUTOPLT, I DID HAVE TO MAKE A SLIGHT (10-15 DEG), MOMENTARY L YOKE INPUT. 1 OF MY 2 JUMP SEATERS MENTIONED SPINDLE FAILURE, BUT I DISMISSED IT IMMEDIATELY BECAUSE, 1) THERE WAS ABSOLUTELY NO UNUSUAL ROLL OR YAW, AND 2) I WAS NOT AWARE OF ANY COMPANY B-300 ACFT EXPERIENCING SPINDLE FAILURES. I THEREFORE DID NOT PERFORM THE SUSPECTED FLAP SPINDLE FAILURE PROC. WE LANDED UNEVENTFULLY. AFTER LNDG, THE JUMP SEATER INFORMED ME WE HAD EXPERIENCED B-300 SPINDLE FAILURES. AS A PRECAUTION, WE CALLED MAINT AND DESCRIBED THE PROB. THEY DID FIND A BROKEN SPINDLE ON THE R WING. SUPPLEMENTAL INFO FROM ACN 625178: WE ALL WONDERED WHAT THE SOUND WAS. (WE HAD 2 COCKPIT JUMP SEATERS.) THE CAPT THOUGHT IT SOUNDED LIKE A LATE GEAR DEPLOY. THE JUMP SEATERS AND I DIDN'T THINK SO, SINCE WE HAD BEEN SHOWING 3 GREEN WELL BEFORE THE POP. WE MENTIONED SPINDLE FAILURE, BUT DISCOUNTED SINCE THERE WAS NO ROLL-OFF. THOUGHT IT WAS PROBABLY A BIRD AND WE WOULD MAKE SURE THE ON-COMING CREW DID A GOOD INSPECTION. TAXIING IN WE DISCUSSED WHAT THE NOISE COULD BE. AFTER DISCUSSING, WE AGREED IT SOUNDED MORE MECHANICAL THAN BIRD STRIKES WE HAD EXPERIENCED IN PAST. WE DIDN'T THINK SPINDLES WERE AS BIG OF AN ISSUE IN THE B-300 AS OPPOSED TO THE B-200, BUT KNEW IT COULD HAPPEN. ONE OBSERVER HAD JUST RETURNED FROM TRAINING AND SAID THAT COMPANY HAD A FEW SPINDLE FAILURES IN B-300. MAINT DID A SPINDLE CHK, AND DISCOVERED THE R OUTBOARD SPINDLE BROKEN.

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.