A B737-400 IN CLB AT 2000 FT; FLAPS RETRACTING FROM 5 TO 1 UNITS; EXPERIENCED UNCOMMANDED NOSE DOWN ATTITUDE WITH CLB POWER. A FLAP OVERSPD OF 8 KTS WAS EXPERIENCED.

Narrative

ON CLBOUT AT APPROX 2000 FT MSL; FLAPS 5 BEING RETRACTED TO FLAPS 1; ACFT ACCELERATING; THE ACFT WENT INTO AN UNCOMMANDED NOSE DOWN ATTITUDE WITH CLB POWER SELECTED. NOSE UP TRIM SELECTED BUT SLOW TO RESPOND WITH A HVY CTL YOKE TO BRING ACFT TO LEVEL AND CLB ATTITUDE. AS THE ACFT BEGAN GRADUAL DSCNT; AIRSPD INCREASED RAPIDLY BEFORE PF COULD DISENGAGE AUTOTHROTTLES; FLAPS 1 OVERSPD OCCURRED BY APPROX 8 KTS (258 KTS INDICATED). ONCE AIRSPD DECREASED AND FLAPS RETRACTED; NO OTHER FLT CTL PROBS WERE EVIDENT AND NO OTHER ABNORMAL INDICATIONS WERE PRESENT. FLT CONTINUED TO ZZZ WITH NORMAL DSCNT APCH AND LNDG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE UNCOMMANDED NOSE DOWN ATTITUDE CHANGE WAS CAUSED BY THE AUTOPLT STABILIZER TRIM. THE FLT RECORDER WAS REMOVED AND ESTABLISHED THAT A 700 FT PER MIN DSCNT WAS INITIATED. THE RPTR STATED THE AUTOPLT AND AUTOTHROTTLE SYSTEMS WERE SWITCHED OFF; BUT A FLAP OVERSPD OCCURRED BY 8 KTS. ONCE AIRSPD WAS DECREASED AND FLAPS RETRACTED; ALL FLT CTLS WERE NORMAL. MAINT ACTION WAS REPLACEMENT OF STABILIZER TRIM SWITCH AND THE LOW SPD JACKSCREW ACTUATOR.