A B747-100 WAS DISPATCHED AND OPERATED FOR 2 FLT LEGS WITH INTERMITTENT TEST OF #4 ENG L AND R FIRE BOTTLE SQUIBS.

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I'M A FLT MECH WHO TRAVELS WITH THE ACFT. I'M ASSIGNED TO AN ACFT GENERALLY FOR A 3-WK TERM. I AM ATTACHING THE STATEMENT I MADE FOR MY SUPVR CONCERNING THIS SIT WHICH ALSO WILL BE GIVEN TO THE FAA PMI WHO IS INVESTIGATING. ON NOV/MON/04; I WAS VERBALLY INFORMED THAT THERE WAS A LETTER OF INVESTIGATION CONCERNING THIS SIT. AS OF TODAY; (DEC/THU/04); I HAVE NOT RECEIVED ANY NOTIFICATION FROM THE FAA. I THINK THERE ARE PROBS WITH HOW THE MEL IS WRITTEN ON THE SIT; REF 26-17 AND 26-17 SPECIAL PROCS OF THE MEL AND THE TOOLING/TEST UNIT (PARTS) AVAILABILITY. I HAVE BEEN VERBALLY INFORMED THAT THE MEL IS BEING CHANGED AND THAT A PRE-MADE TEST UNIT FOR THIS PROC IS BEING MADE AND PLACED ON EACH B747 ACFT AT AIRLINE. I DO NOT KNOW WHEN THE FIRE BOTTLES WERE DISCHARGED. IF THEY WERE INADVERTENTLY DISCHARGED IN ZZZ; WE HAD NO INDICATIONS THAT THEY WERE. THEY MAY HAVE BEEN DISCHARGED IN ZZZ1; WHILE THE SYS WAS TROUBLESHOT THERE. I'M NOT POINTING FINGERS; I JUST DON'T KNOW. LOOKING BACK; I CAN'T POINT TO A TIME WHERE I THINK I MAY HAVE DISCHARGED THE BOTTLES. THIS PROB WAS A CONTINUING ITEM. TWICE MORE THE #4 R BOTTLE INDICATOR LIGHT CAME UP AND WAS REPAIRED WITH DIFFERENT REPAIRS SOLVING THE PROB. I DO FEEL WE MAY HAVE OR HAD A WIRING OR GND FAULT IN THE SYS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR MADE THE SQUIB TEST PRIOR TO DEP AND NOTED THE SQUIB TEST LIGHT CIRCUIT WAS INTERMITTENT AND THE TEST EQUIP TO TEST FIRE BOTTLE SQUIBS WAS NOT AVAILABLE FOR A POSITIVE TEST. THE MEL FOR THIS AIRPLANE REGARDING THE DEFERRAL OF THE SQUIBS L AND R WAS CONFUSING AND IS BEING REWRITTEN TO ALLOW A CONTINUITY TEST OF THE SQUIBS WITH A SPECIAL SQUIB TESTER AND IF THE SQUIBS TEST GOOD THEN THE LIGHT TEST CIRCUIT CAN BE DEFERRED. THE TESTER WAS NOT AVAILABLE AND THE NORMAL TEST WAS ACCOMPLISHED. THE TEST CAME UP GOOD THIS TIME AND THE DECISION WAS MADE TO DEFER THE LIGHT CIRCUIT. THIS AIRPLANE WAS FLOWN TO A MAINT FACILITY AND AFTER SEVERAL DAYS IN MAINT THE #4 ENG FIRE BOTTLES WERE FOUND DISCHARGED. THIS IS BELIEVED TO HAVE HAPPENED IN THE MAINT FACILITY DURING THE REPAIR OF THE SQUIB TEST LIGHT CIRCUIT.