Narrative:

Engine anti-ice system performed normally on first officer's takeoff and climb out from cincinnati/northern kentucky international airport (cvg). Outside air temperature increased as we climbed through clouds. Engine anti-ice was turned off at approximately 4000 ft MSL and plus 8 degrees C outside air temperature. Engine anti-ice was selected on at approximately 5000 ft MSL as outside air temperature was decreasing from plus 10 degrees to plus 8 degrees C. 'Ice protection' central warning panel light illuminated with 'left air valve' light on overhead panel. Captain recycled left engine anti-ice switch, which did not solve the problem. Captain then retarded left power lever to approximately 50 percent torque to manually open the anti-ice/start bleed valve, per the abnormal procedures checklist. 'Left air valve' light went out on overhead panel. Captain began smoothly reapplying climb torque to left engine. Torque, propeller and gas generator RPM indications fluctuated wildly for approximately 3 seconds. Captain moved left condition lever to 'T/M lockout' (torque motor lockout) position in response to uncommanded power plant indications, per abnormal procedures checklist. All indications for left engine were now decreasing toward zero as 'left engine oil pressure' central warning panel light illuminated. Captain secured left condition lever to 'fuel off' position and requested control of aircraft. Controls were transferred from first officer to captain. First officer completed 'engine fire/failure in flight' emergency checklist. An emergency was declared to ATC, and we returned to cvg. First officer completed climb, cruise, descent, approach, and before landing 'single engine operations' abnormal procedures checklist. A successful single engine landing was made at cvg.

Related reports:

Google
 

Original NASA ASRS Text

Title: FLC OF AN MDT DECLARED AN EMER AND RETURNED TO LAND AFTER LOSING THE PWR OF 1 ENG IN ICING CONDITIONS.

Narrative: ENG ANTI-ICE SYS PERFORMED NORMALLY ON FO'S TKOF AND CLBOUT FROM CINCINNATI/NORTHERN KENTUCKY INTL ARPT (CVG). OUTSIDE AIR TEMP INCREASED AS WE CLBED THROUGH CLOUDS. ENG ANTI-ICE WAS TURNED OFF AT APPROX 4000 FT MSL AND PLUS 8 DEGS C OUTSIDE AIR TEMP. ENG ANTI-ICE WAS SELECTED ON AT APPROX 5000 FT MSL AS OUTSIDE AIR TEMP WAS DECREASING FROM PLUS 10 DEGS TO PLUS 8 DEGS C. 'ICE PROTECTION' CENTRAL WARNING PANEL LIGHT ILLUMINATED WITH 'L AIR VALVE' LIGHT ON OVERHEAD PANEL. CAPT RECYCLED L ENG ANTI-ICE SWITCH, WHICH DID NOT SOLVE THE PROB. CAPT THEN RETARDED L PWR LEVER TO APPROX 50 PERCENT TORQUE TO MANUALLY OPEN THE ANTI-ICE/START BLEED VALVE, PER THE ABNORMAL PROCS CHKLIST. 'L AIR VALVE' LIGHT WENT OUT ON OVERHEAD PANEL. CAPT BEGAN SMOOTHLY REAPPLYING CLB TORQUE TO L ENG. TORQUE, PROP AND GAS GENERATOR RPM INDICATIONS FLUCTUATED WILDLY FOR APPROX 3 SECONDS. CAPT MOVED L CONDITION LEVER TO 'T/M LOCKOUT' (TORQUE MOTOR LOCKOUT) POS IN RESPONSE TO UNCOMMANDED POWER PLANT INDICATIONS, PER ABNORMAL PROCS CHKLIST. ALL INDICATIONS FOR L ENG WERE NOW DECREASING TOWARD ZERO AS 'L ENG OIL PRESSURE' CENTRAL WARNING PANEL LIGHT ILLUMINATED. CAPT SECURED L CONDITION LEVER TO 'FUEL OFF' POS AND REQUESTED CTL OF ACFT. CTLS WERE TRANSFERRED FROM FO TO CAPT. FO COMPLETED 'ENG FIRE/FAILURE IN FLT' EMER CHKLIST. AN EMER WAS DECLARED TO ATC, AND WE RETURNED TO CVG. FO COMPLETED CLB, CRUISE, DSCNT, APCH, AND BEFORE LNDG 'SINGLE ENG OPS' ABNORMAL PROCS CHKLIST. A SUCCESSFUL SINGLE ENG LNDG WAS MADE AT CVG.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.