A B747 CREW SURMISE A FIRM LNDG AT SAIPAN (PGSN) WAS DUE TO A FLAP PROB.

Narrative

THIS LEG STARTED IN NARITA; JAPAN AND WAS SCHEDULED TO LAND ON SAIPAN ISLAND. THE FLT STARTED OFF ROUTINELY. I DID; HOWEVER; NOTICE THAT IT WAS DIFFICULT TO TRIM UP THE ACFT WHILE CLBING OUT; ESPECIALLY LATERALLY. WITH MY LACK OF EXPERIENCE ON THIS ACFT TYPE; I DETERMINED IT WAS AN IDIOSYNCRASY OF THIS AIRPLANE IN PARTICULAR. NOTHING OUT OF THE ORDINARY OCCURRED ENRTE. APCHING SAIPAN; WE RECEIVED THE WX OVER VOICE AND VIA ACARS. WE KNEW THERE WOULD BE RAIN SHOWERS OVER THE AREA; RAGGED CEILINGS; AND GUSTY WINDS. IN BRIEFING THE APCH; DISCUSSION INCLUDED SELECTING MINIMUM BRAKES DUE TO A POSSIBLY WET RWY. THE CAPT VOICED THE OPINION THAT AT OUR GROSS WT; ABOUT 580000 LBS; WE DID NOT WANT A PROB LNDG LONG ON THE 7500 FT RWY. PREVIOUS EXPERIENCE INTO SAIPAN HAD SHOWN THAT WITH AN EARLY DSCNT; OFTENTIMES ONE COULD VISUALLY OBTAIN THE RWY EARLY ENOUGH SO AS TO PRECLUDE LENGTHY VECTORING. THAT WAS THE PLAN UNTIL WE WERE INFORMED THAT WE WERE #3 FOR APCH AND LNDG; TO SLOW UP SOME 100 MI FROM THE FIELD; AND THAT THERE WERE RAIN SHOWERS ON FINAL; SO WE WERE TO EXPECT THE ILS TO RWY 7. WE WERE GIVEN DELAYING VECTORS; AND SOME 30 MI FROM THE FIELD; WE WERE FINALLY GIVEN A HEADING TO INTERCEPT THE LOC. AT 5000 FT MSL ON FINAL APCH; WE DECIDED TO FOLLOW THE GS DOWN. ONCE ON FINAL; HAVING SLOWED TO MANEUVERING AIRSPD WITH FLAPS OUT AT 10 DEGS; THEN 20 DEGS WITH GEAR DOWN; THEN 25 DEGS; I NOTICED IT WAS TAKING MUCH EFFORT TO CTL ACFT HEADING WITHIN +/-15 DEGS EITHER SIDE OF COURSE. THIS WAS IN MY MIND A LITTLE EXCESSIVE FOR THE WIND CONDITIONS; WHICH WERE PRETTY MUCH A STRAIGHT HEADWIND. PITCH CTL ALSO SEEMED SLIGHTLY HVY. DESPITE ALL OF THAT; THE OTHER CREW MEMBERS NOTED THAT I HAD THE APCH 'WIRED' (LITTLE DID THEY REALIZE HOW MUCH EFFORT I WAS PUTTING INTO CTLING THE ACFT TO MAKE IT SEEM THAT WAY). WE BROKE OUT ABOUT 1 1/2 MI OUT ONCE WE GOT BELOW THE RAGGED CEILING; ABOUT 500-600 FT MSL. I KEPT PEERING PERIODICALLY AT MY FLT INSTS WHILE TRANSITIONING TO A VISUAL APCH; UNTIL I KNEW WE WERE CLR OF ALL OBSCURATIONS. THE CAPT ANNOUNCED ON SHORT FINAL (100-200 FT AGL) THAT MY AIRSPD WAS ABOUT VREF; SO I ADDED A LITTLE PWR; KEEPING THE GUSTY WINDS IN MIND. I HEARD THE 100 FT VOICE COMMAND FLARE TONE; AND I KEPT THE DSCNT GOING. THE 30 FT VOICE COMMAND FLARE TONE WENT OFF; AND I STARTED FLARING. THE 20 FT VOICE COMMAND FLARE TONE THEN WENT OFF; AND I PULLED BACK MORE. IT DID NOT FEEL LIKE I COULD PULL THE NOSE UP ANY MORE; IT FELT AS IF SOMETHING WAS PUSHING DOWN ON THE ACFT. WE NEVER RECEIVED A SINK RATE OR ANY OTHER KIND OF WARNING THROUGHOUT THE APCH AND LNDG. THE ACFT TOUCHED DOWN STRAIGHT AHEAD WITH AN INCOMPLETE FLARE; ALMOST LIKE STUFFING A SHOE OR STUBBING A TOE. NO CRAB WAS FELT; AND WE TAXIED THE ACFT TO THE GATE PERFORMING THE NORMAL FLOW PATTERNS AND CHKLISTS WITHOUT INCIDENT. THE LNDG HAD BEEN FIRM; BUT WE ALL AGREED WE HAD BEEN PRIVY TO MUCH FIRMER; HARDER LNDGS. NO PANELS OR OXYGEN MASKS HAD FALLEN DOWN. ON THE SO'S SUBSEQUENT PREFLT 1 1/2 HRS LATER; HE DISCOVERED THE L INBOARD FLAP CANOE SEEMED TO HAVE COME DISLODGED; THE FLAP HAD IMPINGED THE L AILERON; AND A FLAP ROD ASSEMBLY HAD BROKEN OFF ITS BRACKET. WHETHER THIS MAINT PROB HAD OCCURRED WHILE BRINGING THE FLAPS UP; EITHER ON CLBOUT OR AFTER LNDG; OR WHILE BEING DEPLOYED; IS ANYONE'S GUESS RIGHT NOW. AS FAR AS THE LNDG WAS CONCERNED; IT MAY HAVE OCCURRED IN PART BY THE FLAP PROB; A DOWNDRAFT; OR A LOSS OF GUST. OTHER CONTRIBUTING FACTORS INCLUDED THE VOICE COMMAND FLARE TONES; LACK OF CREW EXPERIENCE (THE CAPT HAD JUST OVER 100 HRS TIME IN COMMAND OF THE B747; I HAVE JUST OVER 250 HRS AND 25 LNDGS IN THE B747) AND CHRONIC FATIGUE (THIS WAS DAY 13 OUT OF 14 ON THE ROAD FOR ME).