What was found
(CAN) PILOTS REPORTED LT ENG JET PIPE OVERHEAT WARNING ACTIVATED DURING CRUISE FOR APPROX 20 SECONDS THEN WENT AWAY BY ITSELF. ACFT RETURNED TO BASE. MX INVESTIGATED AND FOUND A PLUG/PLATE AT APPROX 11 0`CLOCK WITH 1 NUT FOUND IN BOTTOM OF COWL AND THE OTHER NUT LOOSE ABOUT 4 TURNS. NOTE: THIS PLUG IS LOCATED AT SAME ENG STA AS THE ITT PROBES. LOCKING TAB PN 3056T13P01, NUT PN MS9357-10 IT IS UNCLEAR WHEATHER HOT GASES ESCAPING FROM THE LOOSE PLATE CAUSED JET PIPE OVERHEAT WARNING OR THE NUT FALLING DOWN AND CONTACTING THE TERMINAL LUGS OF THE SENSE ELEMENTS. NO RECURRENCE OF FAULT SINCE PLUG/PLATE REINSTALLED.