MECHANIC NOTES THAT AN MD80 AFT TAIL CONE SLIDE FAILED TO INFLATE DURING A ROUTINE MAINTENANCE (OVERHAUL) TEST WHEN THE FIRING CABLE WAS PULLED. AFT ESCAPE SLIDE HAD BEEN INSTALLED FOR THREE YEARS.

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UNABLE TO INFLATE SLIDE FOR ROUTINE MAINT (OVERHAUL) WHEN FIRING CABLE WAS PULLED TO 'FLAT FIRE' SLIDE. UPON FURTHER INVESTIGATION PIN WAS MISSING FROM PULLEY. THESE ARE SUBASSEMBLIES OF REGULAR VALVE ON INFLATION RESERVOIR.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THEY REALIZED THE EXTENT OF THE SAFETY ISSUE; WHEN THE MD80 AFT TAIL CONE ESCAPE SLIDE FAILED TO INFLATE AND EVACUATE THE SLIDE PRESSURE BOTTLE DURING THE FLAT FIRE TEST PROCEDURE. THIS TEST CHECKS THE TIME THE SLIDE TAKES TO INFLATE AND ALSO VERIFIES THE SLIDE PRESSURE BOTTLE FULLY EVACUATES. THIS SLIDE HAD BEEN INOPERATIVE SINCE IT WAS INSTALLED THREE YEARS EARLIER ON THE MD80. ITS LAST FLAT FIRE TEST WAS IN 2006. REPORTER STATED THE COUPLING PIN FROM THE ROTATING PULLEY TO THE BOTTLE VALVE SHAFT WAS MISSING. THE PIN SLIDES INTO THE VALVE SHAFT AND ALSO FITS INTO A SLOTTED T ON THE INNER SIDE OF THE PULLEY; BUT CAN FALL OUT DURING THE BUILDUP PROCESS OF THE PULLEY TO THE SLIDE BOTTLE. A VALVE PLATE COVER HOLDS THE PULLEY IN POSITION. THE SLIDE BOTTLES ARE COMPOSITE AND DO NOT HAVE TYPICAL PRESSURE GAUGE WITH NUMBERS; BUT RATHER A GAUGE WITH A GREEN BAND THAT IS BASICALLY A GO-NO-GO GAUGE. ALTHOUGH THE RELEASE CABLE ROTATED THE PULLEY; THE BOTTLE VALVE SHAFT WOULD NOT OPEN DUE TO THE MISSING COUPLING PIN. THE SLIDE WAS COMPLETELY NONFUNCTIONAL AS PART OF THE AFT TAIL CONE JETTISON SYSTEM; EVEN THOUGH THE BOTTLE WAS PROPERLY CHARGED.