DH8 EXPERIENCES AN AUTOFEATHER CONDITION; INFLT ENG SHUTDOWN; AFTER ROTATION FROM RWY AT PHL. PIC; PNF; NOTED TORQUE GAUGE PROB PRIOR TO EVENT AND ELECTED TO HAVE FO CONTINUE TKOF.

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ON TKOF WE LOST PWR ON THE #2 ENG; SHORTLY AFTER ROTATION. FLC COMPLETED EMER PROCS AND RETURNED TO THE ARPT; LNDG UNEVENTFULLY. THE PNF (CAPT) NOTICED A PROB WITH THE #2 ENG TORQUE GAUGE DURING TKOF ROLL AND DECIDED TO CONTINUE; MAKING ONLY NORMAL TKOF CALLOUTS. THE TKOF CONTINUED AND THE ENG LOST PWR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE TORQUE GAUGE IS AN INTEGRAL PART OF THE AUTOFEATHERING SYS ON THE DH8. IF THERE IS A FAULT WITHIN THE TORQUE GAUGE AND SOME OTHER PARAMETERS ARE MET; THE ACFT WILL EXPERIENCE AN UNCOMMANDED AUTOFEATHER OF THAT ASSOCIATED ENG. THE ENG ON THE DH8 FEATHERS ON TORQUE SENSING; UNLIKE SOME OTHER TYPES WHICH FEATHER ON OIL PRESSURE SENSING. THE CAPT HAD NOTED A GAUGE FLUCTUATION AT THE GATE BUT AFTER A PWR ALTERATION THE GAUGE APPEARED TO BE NORMAL. NEITHER PLT KNEW OF THIS EQUIP TIE-IN AND IT IS NOT PUBLISHED IN THE POM. THE CREW WAS LATER CALLED IN AND PLACED OFF DUTY FOR 45 DAYS FOR FAILING TO RETURN TO THE GATE AFTER THE FIRST FAULTY INDICATION. SUPPLEMENTAL INFO FROM ACN 378291: AFTER STARTING THE ENGS ON A DASH 8; WE GOT A FLUCTUATION ON THE R TORQUE GAUGE. MISTAKENLY THINKING IT WAS A FAULTY GAUGE; WE TOOK OFF AND GOT AN UNSCHEDULED PROP FEATHER AT ABOUT 40 FT MSL. WE SHUT THE ENG DOWN; AND RELANDED AT PHL. ALSO; AFTER WE LANDED; THERE WAS QUITE A BIT OF OIL OUT OF THAT ENG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE R ENG TORQUE INDICATOR WAS FLUCTUATING BUT I THOUGHT IT WAS ONLY AN INDICATOR PROB AND STARTED THE TKOF. THE RPTR SAID THE COMPANY POLICY IS ANY FLUCTUATING TORQUE INDICATION MUST BE CHKED OUT TO PREVENT MALFUNCTION OF THE PROP AUTOFEATHER SYS. THE RPTR STATED THE ACFT FLEW GREAT ON SINGLE ENG OP. THE RPTR STATES NO DETAILS WERE AVAILABLE FROM MAINT ON THE COMPONENT THAT FAILED.