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A B737-200 captain performed a split flap maneuver (ie, retracting flaps to the previous unsplit setting and adding bug speed) while on approach to slc.
| Attributes | |
| ACN | 451200 |
| Time | |
| Date | 199910 |
| Day | Mon |
| Local Time Of Day | 0001 To 0600 |
| Place | |
| Locale Reference | airport : slc.airport |
| State Reference | UT |
| Altitude | msl single value : 5000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tower : slc.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Route In Use | approach : visual |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 200 flight time total : 14000 flight time type : 8000 |
| ASRS Report | 451200 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : multi engine pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : critical |
| Independent Detector | other flight crewa other flight crewb other other : cab 5 |
| Consequence | other other |
| Supplementary | |
| Problem Areas | Aircraft Maintenance Human Performance |
| Primary Problem | Aircraft |
Narrative:
On final approach. Selected flaps 30 degrees (from a setting of 25 degrees). Heard a 'thump' from right side of airplane and the airplane then displayed a left rolling tendency. Roll was easily countered with aileron input and rudder control was normal. Retracted flaps to 25 degrees, increased airspeed, and accomplished a normal landing, although right wheel input was required all the way to touchdown. Flight attendants at forward flight attendant jump seat reported hearing the 'thump' also. Found no evidence of bird strike or any visible damage on postflt walkaround. The following day, company maintenance personnel spent all day checking the flaps system. They replaced a flap fairing roller and returned the aircraft to service. A couple of days later, I learned that the airplane experienced the same type of occurrence and was removed from service to correct a flap carriage problem (a mid flap had been 'handing up'). No abnormal flap indications were noted in the cockpit.
Original NASA ASRS Text
Title: A B737-200 CAPT PERFORMED A SPLIT FLAP MANEUVER (IE, RETRACTING FLAPS TO THE PREVIOUS UNSPLIT SETTING AND ADDING BUG SPD) WHILE ON APCH TO SLC.
Narrative: ON FINAL APCH. SELECTED FLAPS 30 DEGS (FROM A SETTING OF 25 DEGS). HEARD A 'THUMP' FROM R SIDE OF AIRPLANE AND THE AIRPLANE THEN DISPLAYED A L ROLLING TENDENCY. ROLL WAS EASILY COUNTERED WITH AILERON INPUT AND RUDDER CTL WAS NORMAL. RETRACTED FLAPS TO 25 DEGS, INCREASED AIRSPD, AND ACCOMPLISHED A NORMAL LNDG, ALTHOUGH R WHEEL INPUT WAS REQUIRED ALL THE WAY TO TOUCHDOWN. FLT ATTENDANTS AT FORWARD FLT ATTENDANT JUMP SEAT RPTED HEARING THE 'THUMP' ALSO. FOUND NO EVIDENCE OF BIRD STRIKE OR ANY VISIBLE DAMAGE ON POSTFLT WALKAROUND. THE FOLLOWING DAY, COMPANY MAINT PERSONNEL SPENT ALL DAY CHKING THE FLAPS SYS. THEY REPLACED A FLAP FAIRING ROLLER AND RETURNED THE ACFT TO SVC. A COUPLE OF DAYS LATER, I LEARNED THAT THE AIRPLANE EXPERIENCED THE SAME TYPE OF OCCURRENCE AND WAS REMOVED FROM SVC TO CORRECT A FLAP CARRIAGE PROB (A MID FLAP HAD BEEN 'HANDING UP'). NO ABNORMAL FLAP INDICATIONS WERE NOTED IN THE COCKPIT.
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.