PLT SEAT ADJUSTMENT HANDLES EASILY BROKEN; PREVENTING SEAT ADJUSTMENT BACKWARDS FOR QUICK EGRESS.

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THIS IS AN ALERT TO THE POSSIBILITY OF INADEQUATE STRENGTH SEAT ADJUSTMENT HANDLES. IN MY 4 MONTHS EXPERIENCE ON THIS ACFT; I HAVE EXPERIENCED THE FOLLOWING FAILURES: 1) 2 FORE/AFT SEAT ADJUSTMENT HANDLE FAILURES THAT STILL PROVIDED ENOUGH LEVERAGE FOR OP WITH EXTREME EFFORT. THIS WOULD HAVE BEEN INADEQUATE FOR RAPID/EMER OP. 2) 2 FORE/AFT SEAT ADJUSTMENT HANDLE FAILURES THAT RESULTED IN LOSS OF OP. A) 1 WAS FOUND ON PREFLT INSPECTION. B) 1 BROKE DURING ATTEMPT TO ASSIST CABIN CREW WITH PAX DEPLANING AFTER 'MINOR' ELECTRICAL FIRE. INSTEAD OF A RAPID COCKPIT EXIT; I HAD TO THEN RETRACT THE TABLE TRAY AND CLB OVER CENTER PEDESTAL. 3) 1 FORE AFT SEAT ADJUSTMENT INTERNAL MECHANISM FAILURE. WAS UNABLE TO MOVE SEAT POS; BUT IT OCCASIONALLY UNLOCKED AND SLID TO FULL AFT POS. THIS REQUIRED REPLACEMENT OF THE SEAT/PEDESTAL ASSEMBLY. THE BREAKAGES HAVE CAUSED 2 FLT DELAYS; BUT ALL REQUIRED MAINT ATTN. I AM CONCERNED OF POSSIBLE CONSEQUENCES DURING AN EMER EVAC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR HAS MADE A RPT TO HIS COMPANY AND HIS ALPA SAFETY COMMITTEE. HAS HEARD 1 OR 2 RPTS FROM OTHER PLTS AND HAS HEARD THAT MAINT HAS HAD TO REPLACE NUMEROUS SEAT ADJUSTMENT HANDLES.