ACR WDB HAS TAILPIPE FIRE AFTER SHUTDOWN AT GATE.

Narrative

ENGS WERE SHUT DOWN AND NORMAL SPD DOWN AND COOL DOWN. SECURING CHKLIST ACCOMPLISHED; APU INOP SINCE 9/FRI/88. NO GND AIR WAS CONNECTED. GND ELECTRIC WAS CONNECTED. I HAD LEFT THE ACFT. I WAS LATER INFORMED THAT SOMEONE CAME ONBOARD AND RPTED A TAILPIPE FIRE IN #2 ENG. NO AIR WAS AVAILABLE TO ROTATE ENG; WHICH WOULD BE NORMAL PROC; ACCOUNT INOP APU. CAUSE OF FIRE UNKNOWN TO ME. FIRE WAS AGGRAVATED BY LACK OF AN APU--INOP FOR 6 DAYS. CORRECTIVE ACTION RECOMMENDED: BETTER MAINT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: CONFIRMED #2 ENG AS THE ONE OF THE TAILPIPE FIRE. ALL OF CREW HAD DEPARTED ACFT EXCEPT CAPT WHO HAD DELAYED TO GO TO HEAD AND WHEN GND CREW RUSHED ON BOARD TO RPT FIRE; CAPT TRIED TO MOTORIZE ENG PER PROC TO PUT OUT FIRE; BUT WITH NO AIR AVAILABLE ACCOUNT APU INOP AND GND AIR CART; ALTHOUGH AVAILABLE NOT HOOKED UP AND RUNNING; WAS UNABLE. FIRE DEPT ARRIVED AND PUT OUT FIRE. NO FURTHER FEEDBACK ON CAUSE; BUT SUSPECT PRESSURIZED FUEL MANIFOLD LEAKED AND VAPORIZED INTO HOT TAILPIPE. DID NOT THINK WAS DAMAGE TO ACFT.