FLC ENCOUNTERED STATIC DISCHARGES THAT CAUSED FAILURE OF FLT INSTS. ERRATIC INDICATIONS FROM EFIS INCLUDING R ENG PARTIAL FIRE WARNING (NO MASTER WARNING) SECURED ENG BUT DID NOT BLOW FIRE BOTTLES. EFIS (ELECTRICAL FLT INST SYS).

Narrative

WHILE LEVEL AT 11000 FT MSL IN IMC CONDITIONS WITH AN OAT OF PLUS 5 DEG C SEVERAL STATIC DISCHARGES OCCURRED ON THE WINDSCREEN. WITHIN A COUPLE OF MINS AFTER THE FIRST DISCHARGE BOTH CAPT'S AND FO'S PRIMARY FLT DISPLAYS AND NAV DISPLAYS WENT BLANK (EFIS). THERE WERE NO INDICATIONS ON THE CENTRAL WARNING PANEL OR MASTER WARNING. AFTER THIS OCCURRENCE ACFT ATTITUDE; ALT; AIRSPD AND NAV WERE CONDUCTED BY REF FROM THE STAND-BY INSTS LOCATED ON THE CAPT'S CTL PANEL. THE EMER CHKLIST WAS COMPLIED WITH. PRIOR TO DEP DEST ARPT WX WAS RPTED VFR AND THE RADAR WAS OTS. LOWER ALTS TO VFR WERE REQUESTED. SEVERAL MINS AFTER THE EFIS FAILURE THE #2 COMS RADIO BEAMED INOP; DUE TO STATIC. AT APPROX 35 DME FROM DEST ARPT AT 5000 FT VFR CONDITIONS WERE MAINTAINED AND THE #2 COMS RADIO WAS ONCE AGAIN USABLE. AT APPROX 18 DME THE R ENG FIRE WARNING ILLUMINATED. WE DID NOT HOWEVER RECEIVE A MASTER WARNING OR ANY CENTRAL WARNING PANEL CAPTIONS. ALL ENG INDICATORS AND INSTS WERE NORMAL. THE ENG VISUALLY APPEARED NOT TO BE IN ANY DISTRESS. THE WORKLOAD AT THIS POINT WAS VERY HVY; DUE TO THE ENG FIRE EMER; APCH AND LNDG CHKLISTS NEEDED TO BE PERFORMED; WHILE REQUESTING THE EMER EQUIP AND ADVISING THE CABIN CREW. THE EMER CHKLIST WAS COMPLETED EXCEPT FOR THE DISCHARGE OF FIRE BOTTLES AND CLEAN UP ITEMS. DUE TO THE WORKLOAD AND THE SUSPICION OF A POSSIBLE FALSE FIRE WARNING. LNDG WAS WITHOUT ANY FURTHER INCIDENT. THERE WAS NO ACFT DAMAGE OR INJURY TO PAXS. BOTH FLC MEMBERS HAD KNOWLEDGE OF PAST FALSE FIRE WARNINGS DUE TO FAULTY FIRE LOOPS. THE ACFT ALSO HAS PAST HISTORY OF TORQUE FLUCTUATIONS; PWR ROLL BACKS; AUTO FEATHERS AND EFIS FAILURES. THE SUSPECT CAUSE WAS IMPROPER ACFT BONDING; WHICH HAS BEEN RESOLVED BY PROPER MAINT.