B737-400 FLT CREW EXPERIENCES FLAP AND AUTOPLT ANOMALIES DUE TO RAG LEFT IN THE FLAP JACKSCREW MECHANISM.

Narrative

ON TKOF DURING ACCELERATION AND ACFT CLEANUP; WE HAD A FLAP RETRACTION ISSUE. THE FO WAS FLYING THE ACFT AND I WAS THE PNF. WHEN FLAPS WERE SELECTED FROM 1 DEG TO UP; THE FLAP GAUGES DID NOT MOVE; THERE WAS NO INDICATION OF ASYMMETRY AS BOTH NEEDLES WERE TOGETHER -- SHOWING NO SPLIT; AND THE LED LIGHT WAS 'GREEN.' I RESELECTED THE FLAP LEVER TO 2 DEGS AND THE FLAPS MOVED CORRECTLY TO 2 DEGS. I THEN SELECTED THE FLAPS TO 1 DEG -- NORMAL MOVEMENT AND INDICATIONS. I THEN SELECTED THE FLAPS TO UP AND THIS TIME THEY REACTED NORMALLY TO 'UP' AND THE LED LIGHT WAS OUT -- ALL LOOKED CORRECT AND NORMAL -- 'CLEAN WING.' AT APPROX 5000 FT ON CLBOUT AT 250 KTS; THE 'B' AUTOPLT DISENGAGED AND DESPITE SEVERAL ATTEMPTS BY THE FO; WOULD NOT RE-ENGAGE. I SCANNED ALL CIRCUIT BREAKERS AND THEN RECYCLED THE AUTOPLT DISENGAGE SWITCHES AND WE ATTEMPTED AGAIN -- NO HELP. WE THEN TRIED TO ENGAGE THE 'A' AUTOPLT AND IT WOULD NOT ENGAGE EITHER. DURING THIS CLBOUT PERIOD WE WERE IN VERY TURBULENT AIR AND IN IMC WX CONDITIONS; A SATURATED ATC ENVIRONMENT WITH CONGESTED RADIO TFC; MULTIPLE HDG AND ALT CHANGES; AND UNABLE TO ENGAGE EITHER AUTOPLT TO HELP US 'DOWNLOAD.' WE ELECTED TO MANUALLY FLY THE ACFT UP ABOVE THE CLOUD COVER AND OUT OF THE HVY ATC ENVIRONMENT -- LET THINGS SETTLE DOWN A BIT; AND THEN RE-EVALUATE OUR CONDITION. REACHING CRUISE ALT OF FL330 AND IN THE CLR; WE PULLED OUT THE QRH AND MEL TO REVIEW ALL OPTIONS AND MAKE SURE WE HAD COMPLIED WITH ALL PROCS FOR THE INOP AUTOPLTS. GIVEN THE TURBULENT RIDE WE WERE EXPERIENCING AND THE DIFFICULTY WE WERE HAVING MAINTAINING PRECISE ALT CTL IN ROUGH AIR I WAS RELUCTANT TO CONTINUE THE FLT INTO MEXICAN AIRSPACE. WE WERE NOW REACHING THE MEXICAN BORDER AND UNABLE TO COMPLY WITH RVSM AIRSPACE REQUIREMENTS (NO AUTOPLTS) SO WE ELECTED TO HOLD N OF THE BORDER WHILE WE CONTACTED MAINT CTL AND DISPATCH. AFTER RELAYING OUR FLT CONDITIONS AND INFO TO MAINT CTL AND DISPATCH; THE JOINT DECISION BY ALL CONCERNED WAS TO RETURN THE ACFT TO ZZZ1. RECEIVING A RETURN CLRNC AND DSCNT; AS SOON AS WE PULLED THE THROTTLES BACK FOR DSCNT THE LNDG GEAR WARNING HORN WENT OFF -- INDICATING TO ME WE HAD SOME FURTHER ABNORMAL CIRCUMSTANCES GOING ON (THE SECOND TIME NOW SOMETHING DIDN'T QUITE SEEM RIGHT WITH THE FLAPS). THE FLAPS STILL APPEARED TO BE FULL UP AND NO LED LIGHTS WERE ILLUMINATED --BUT THAT HORN SHOULDN'T BE GOING OFF AT ALT WITH THE FLAPS UP. (YES; WE WERE CONSTANTLY CHKING THE ACFT PRESSURIZATION AND ALL WAS NORMAL AND CORRECT.) WE CONTINUED OUR DSCNT AND RETURN TO BASE WITH 'NORMAL' CONFIGN AND INDICATIONS. LNDG WAS MADE AT FLAPS 30 DEGS; WITH NO FURTHER ABNORMAL INDICATIONS. ON TAXI IN WHEN THE FLAPS WERE RETRACTED; THEY 'STUCK' AT FLAPS 1 DEG AND THE LEADING EDGE FLAP DISAGREEMENT LIGHT WAS 'ON.' WE ELECTED TO LEAVE THE FLAPS AS SET AND NOT MOVE THE FLAP LEVER AND TAXI TO THE GATE IN THIS CONFIGN. TAXI-IN AND GATE ARR WERE NORMAL. AS A FINAL NOTE; UPON TROUBLESHOOTING THE ACFT; THE MECHS FOUND A 'RAG' WRAPPED AROUND THE #7 FLAP DRIVE JACKSCREW AND BINDING THE FLAP DRIVE MECHANISM. DURING PREFLT AND WALKAROUND THIS RAG WAS NOT OBSERVED BY THE FO; AND UNTIL THE FIRST FINAL FLAP RETRACTION AFTER TKOF WE WERE UNAWARE OF ANY ABNORMAL CIRCUMSTANCES.