B767 FLT CREW REPORTS FLAP OVERSPEED ON APPROACH DUE TO WIND SHEAR AND LE FLAP DISAGREE RESULTING IN FLAP 20 LANDING.

Narrative

THE FO WAS THE PF; I WAS IN THE JUMPSEAT ACTING AS RELIEF PLT. WE WERE GIVEN A DSCNT FROM 7000 FT TO 4000 FT FOLLOWED IMMEDIATELY BY A TFC CALL; A TURN TO 180 DEGS (BASE) AND A SPD REDUCTION TO 180 KIAS. WE WERE ALREADY CONFIGURED AT FLAPS 1 DEG AND AT 210 KIAS WITH THE AUTOPLT ENGAGED. WHILE TURNING TO BASE; LOOKING FOR TFC AND SETTING 180 KIAS IN THE MCP IAS/MACH WINDOW; THE ACFT DSNDED THROUGH THE BOTTOM OF A CLOUD LAYER AT APPROX 6000 FT MSL. THERE MUST HAVE BEEN AN INCREASE IN WIND; BECAUSE THE AIRSPD INSTANTANEOUSLY INCREASED TO 262 KIAS; CAUSING A FLAP OVERSPEED MESSAGE ON THE EICAS AND AN AURAL ALERT. THE CAPT ELECTED TO RETRACT THE FLAPS TO ZERO AND WE THEN RECEIVED A LEADING EDGE SLAT DISAGREE EICAS MESSAGE AND LEADING EDGE SLAT CAUTION LIGHT. WE LEVELED AT 4000 FT; ADVISED ATC THAT WE HAD A PROB AND ELECTED TO CONTINUE THE APCH; AS WE WERE ABOUT 10 NM OUTSIDE THE MARKER. THE CAPT TOLD THE FO TO REMAIN FLYING AND HE (CAPT) AND I BEGAN RUNNING THE LEADING EDGE SLAT DISAGREE CHKLIST. AS PER THE CHKLIST; WE PLACED THE LEADING EDGE ALTERNATE FLAPS SWITCH TO ALTN AND TRIED TO LOWER THE FLAPS TO 20 DEGS FOR LNDG USING THE ALTN FLAPS SWITCH (THE LEADING EDGE CAUTION LIGHT HAD GONE OUT AFTER WE SELECTED ALTN WITH THE LEADING EDGE ALTN FLAP SWITCH). WE WERE SURPRISED BY THE FACT THAT THE FLAPS WERE NOT EXTENDING AS WE EXPECTED THEM TO AND WE BEGAN A DISCUSSION AS TO WHY THIS MIGHT BE HAPPENING. THE FO MUST HAVE ALLOWED HIMSELF TO BECOME INVOLVED IN OUR DISCUSSION; BECAUSE THE ACFT SLOWED BELOW CLEAN SPD (THE FO THOUGHT WE WERE LOWERING FLAPS TO 1 DEG AND WAS SLOWING THE ACFT TO THE REF SPD FOR THAT CONFIGN) AND WE RECEIVED A STALL INDICATION (STICK SHAKER AND HORN). THE CAPT ASSUMED CTL OF THE ACFT; RECOVERED; AND INITIATED A GAR. WE FOLLOWED ATC INSTRUCTIONS FOR A TURN TO DOWNWIND AND REQUESTED AN EXTENDED DOWNWIND TO CONTINUE TO RUN OUR ABNORMAL CHKLIST. WE DID DECLARE AN EMER BECAUSE WE ANTICIPATED LNDG WITH REDUCED FLAPS AND HIGHER APCH SPD; BUT I DO NOT RECALL EXACTLY WHEN THE DECLARATION WAS MADE. NOW THE CAPT IS THE PF AND THE FO AND MYSELF HAVE BEEN TASKED WITH RUNNING THE ABNORMAL CHKLIST. WE DECIDED TO GO BACK TO THE BEGINNING OF THE LEADING EDGE DISAGREE CHKLIST AND START IT AGAIN. THIS TIME WHEN WE PLACED THE LEADING EDGE ALTERNATE FLAPS SWITCH TO ALTN; THE LEADING EDGE CAUTION LIGHT REMAINED ILLUMINATED. AS PER THE CHKLIST; THE LEADING EDGE ALTN FLAPS SWITCH WAS PLACED OFF AND WE WERE SENT TO THE LEADING EDGE SLAT ASYMMETRY CHKLIST. NOW THE FLAPS AND SLATS EXTENDED TO 20 DEGS AND WE ACCOMPLISHED OUR APCH AND LNDG WITH FLAPS 20 DEGS AND VREF 30+30. OUR LNDG AND SUBSEQUENT TAXI TO THE GATE WERE NORMAL AND OUR EMER WAS TERMINATED BY THE CAPT. LESSONS LEARNED: THE PF SHOULD DO ONLY THAT AND NOT GET INVOLVED WITH RUNNING THE CHKLISTS (ABNORMAL). THE FORMAT OF THE CHKLISTS CAUSED CONFUSION IN THE HEAT OF BATTLE. SOME OF THE 'IF; THEN' BULLETS SEEM TO LEAD IN UNEXPECTED DIRECTIONS OR LEAVE UNCERTAINTY AS TO THE PROPER DIRECTION TO PURSUE. SUPPLEMENTAL INFO FROM ACN 779681: ATC CLRNC: DSND TO 4000 FT MSL MAINTAIN 220 KTS. R AUTOPLT IN CMD; FLT LEVEL CHANGE; AUTOTHROTTLE IN SPD MODE 220 KTS IN MCP SPD WINDOW; FLAPS UP; SPD BRAKES EXTENDED. ATC REVISED SPD TO 210 KTS. AFTER SETTING 210 IN THE SPD WINDOW I CALLED FOR FLAPS 1 DEG. CAPT SET FLAPS TO 1 DEG. PASSING THROUGH APPROX 4500 FT MSL WE DSNDED BELOW A SCATTERED CLOUD LAYER. I NOTICED THAT THE AIRSPD BEGAN TO INCREASE. ATC CALLED FOR A L TURN TO 180 DEGS; LOOK FOR TFC TO FOLLOW FOR A VISUAL APCH. THE CAPT LOOKED FOR THE TFC AS I SET 180 DEGS ON THE HDG BUG. AS THE ACFT LEVELED AT 4000 FT; THE AIRSPD WAS STILL INCREASING TOWARDS 240 KTS. WHILE THE CAPT WAS BUSY LOOKING FOR TFC I RAISED THE FLAP HANDLE TO AVOID A FLAP OVERSPEED. AIRSPD PEAKED AT APPROX 260 KTS. DURING FLAP RETRACTION THE LEADING EDGE SLAT DISAGREE EICAS MESSAGE ILLUMINATED. AS THE CAPT AND RELIEF PLT BEGAN THE NON-NORMAL CHKLIST I CONTINUED FLYING THE ACFT. ATC CLRED US TO DSND TO 3500 FT AND TO INTERCEPTTHE LOC. IT BECAME EVIDENT THAT WE COULD NOT COMPLETE THE NECESSARY CHKLISTS IN TIME TO ACCOMPLISH A SAFE LNDG. THE CAPT ELECTED TO EXECUTE A MISSED APCH AND TOOK CTL ON THE ACFT. AT THIS POINT IT APPEARED THAT WE MIGHT NOT BE ABLE TO EXTEND THE TRAILING EDGE FLAPS AND MIGHT NEED TO EXECUTE A NO FLAP LNDG. I DECLARED AN EMER AND REQUESTED VECTORS TO THE LONG RWY. ONCE ESTABLISHED ON DOWNWIND THE RELIEF PLT AND I ACCOMPLISHED THE LEADING EDGE SLAT DISAGREE CHKLIST. THE FLAPS EXTENDED TO 20 DEGS AND THE CAPT LANDED WITHOUT FURTHER INCIDENT.