AN SF340 LOSES PART OF ITS COWLING WHILE IN DSCNT INTO MEM. THE PIC HAD PREFLTED THE ACFT ON THE GND PREVIOUS TO FLT AND HAD FOUND NOTHING ABNORMAL.

Narrative

MAY/SUN/98; CREW FLEW SF340 FROM MONROE; LA; TO SHREVEPORT; LA. I PERFORMED POSTFLT INSPECTION; ALL WAS GOOD. CREW THEN FLEW FROM SHREVEPORT TO MEMPHIS; 1 HR INTO THIS (OUR SECOND LEG) AN AERODYNAMIC COWLING AFT OF SPINNER HUB FAILED. OUR FLT ATTENDANT CALLED THE COCKPIT; SHE TOLD ME THAT A PAX NOTED A PIECE MISSING FROM THE ENG AREA (PAX WAS SITTING IN WINDOW SEAT NEXT TO THE L ENG). I LOOKED BACK BEHIND AT ENG. I SAW PART WAS ATTACHED AND PART WAS MISSING. FLT ATTENDANT SAID SHE HEARD OR FELT THE PART DEPART THE ENG JUST PRIOR TO CALLING. OUR POS WAS AROUND 20-25 NM SW OF MEMPHIS BELOW 8000 FT; BEING VECTORED FOR A VISUAL APCH TO RWY 36L. ALL ENG PARAMETERS WERE NORMAL AND ALL FLT CHARACTERISTICS NORMAL. I DECLARED AN EMER; REQUESTED CFR FOR OUR 17 PAX AND 3 CREW; CALLED OPS TO INFORM THEM OF OUR PROB. WE CONTINUED USING L ENG BECAUSE ALL INDICATIONS WERE NORMAL; FO'S LEG AND LNDG. LNDG WAS UNEVENTFUL. IN ADDITION I MADE A PAX PA TO CALM ANY UPSET PAX. UPON DEPLANING THEY WERE VERY NICE. UNSURE OF EXACT LOCATION OF THE PIECE THAT BROKE OFF 20-25 MI FROM MEMPHIS.