Narrative:

After a normal takeoff and climb, aircraft was leveled to cruise at 17000 ft on victor airway 13 with the autoplt selected on. A short time after leveling for cruise, a pop or bang was heard and the aircraft yawed right momentarily. While scanning the right engine instruments, the following were noted: 1) right engine torque dropped to zero immediately, and remained at zero. 2) itt rose rapidly, fluctuated, and exceeded 962 degrees intermittently. 3) right engine overtemp light illuminated intermittently. 4) right propeller RPM rose above 1400 RPM and fluctuated between mid 1400's and well above 1500 RPM. 5) right ignition light illuminated. 6) after a short delay, right oil pressure light illuminated. 7) there was no indication of engine fire. Due to zero torque (total loss of engine power), an increase in drag, a decrease in airspeed, the right propeller overspd, and the other right engine indications listed above, the right engine was shut down via the memory items for an engine failure in flight -- combined with the QRH procedure for propeller RPM over limit. Because of the propeller overspd condition present (in addition to the loss of engine power/torque), the right power lever was not moved to flight idle prior to moving the right condition lever to the fuel off position. This action was taken in order to satisfy the QRH checklist for a propeller overspd. The QRH checklists for engine shutdown and for 1 engine inoperative landing were then completed. Due to the now single engine operation, an emergency was declared with the ZMP controller, with a request for descent. Our position at the time of the failure was approximately 20 mi south of mcw. At the time of failure, we had just exited a cloud layer, and our flight conditions were VMC with a scattered to broken layer below. The mcw airport was first acquired visually a few mins after the failure occurred. It was immediately clear that mcw was the nearest suitable airport, in point of time, at which a safe landing could be made. I also knew that crash fire rescue equipment would be available at mcw. After the approach brief, I took control of the aircraft and few a visual approach to runway 35 at mcw. Except for the single engine condition, the landing was normal. As I turned off at the end of the runway, the first officer called ZMP and informed them we were on the ground at mcw, and IFR was canceled. I then told the first officer to ask the emergency vehicles to follow us as we taxied back to the gate, which they did. Upon visually inspecting the right engine after shutdown, a large amount of oil was noted coating most of the right engine nacelle, and oil was dripping from the forward end of the engine nacelle. Also, during postflt inspection, the right tire was noted to be flat, possibly due to asymmetric braking with the left engine at ground idle. Telephone calls were made to air carrier dispatch and to air carrier maintenance. The failure and flat tire were entered into the aircraft's maintenance log. Preflight action: prior to departure from ZZZ, the first officer noted during preflight that the right propeller resisted rotation when turned by hand. I went outside to inspect it myself, found this to be true, (smooth, quiet resistance), and notified maintenance in ZZZ. The on-site air carrier maintenance person in ZZZ commented that he had noticed it earlier as well and said, 'let's run it,' to check its operations and indications. The right engine was then run (started, propeller brought out of and back into feather, and shut down), 3 times before departure -- all 3 with normal propeller behavior and normal engine and propeller indications on the aircraft's gauges. We had seen and spoken with the ZZZ maintenance person upon arrival at the aircraft approximately 20 mins prior to departure. Later, 5-10 mins before scheduled departure from ZZZ, when we initiated the discussion about the right propeller with the air carrier maintenance person, it was not evident that the maintenance person intended to notify the flight crew, before the flight departed, of his prior knowledge of the right propeller's resistance to rotation. During the days after this failure, I discussed the event with air carrier maintenance personnel in the engine shop in the air carrier maintenance hangar. I was told at that time that similar failures had occurred on this engine/gear box model. Further, I was told that gear boxes of this model produced by a particular vendor were specifically more likely to fail in a manner similar to this engine and this failure.

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Original NASA ASRS Text

Title: A SAAB 340 IN CRUISE AT 17000 FT, DECLARED AN EMER AND DIVERTED DUE TO #2 ENG LOSS OF PWR CAUSED BY GEAR BOX FAILURE.

Narrative: AFTER A NORMAL TKOF AND CLB, ACFT WAS LEVELED TO CRUISE AT 17000 FT ON VICTOR AIRWAY 13 WITH THE AUTOPLT SELECTED ON. A SHORT TIME AFTER LEVELING FOR CRUISE, A POP OR BANG WAS HEARD AND THE ACFT YAWED R MOMENTARILY. WHILE SCANNING THE R ENG INSTS, THE FOLLOWING WERE NOTED: 1) R ENG TORQUE DROPPED TO ZERO IMMEDIATELY, AND REMAINED AT ZERO. 2) ITT ROSE RAPIDLY, FLUCTUATED, AND EXCEEDED 962 DEGS INTERMITTENTLY. 3) R ENG OVERTEMP LIGHT ILLUMINATED INTERMITTENTLY. 4) R PROP RPM ROSE ABOVE 1400 RPM AND FLUCTUATED BTWN MID 1400'S AND WELL ABOVE 1500 RPM. 5) R IGNITION LIGHT ILLUMINATED. 6) AFTER A SHORT DELAY, R OIL PRESSURE LIGHT ILLUMINATED. 7) THERE WAS NO INDICATION OF ENG FIRE. DUE TO ZERO TORQUE (TOTAL LOSS OF ENG PWR), AN INCREASE IN DRAG, A DECREASE IN AIRSPD, THE R PROP OVERSPD, AND THE OTHER R ENG INDICATIONS LISTED ABOVE, THE R ENG WAS SHUT DOWN VIA THE MEMORY ITEMS FOR AN ENG FAILURE IN FLT -- COMBINED WITH THE QRH PROC FOR PROP RPM OVER LIMIT. BECAUSE OF THE PROP OVERSPD CONDITION PRESENT (IN ADDITION TO THE LOSS OF ENG PWR/TORQUE), THE R PWR LEVER WAS NOT MOVED TO FLT IDLE PRIOR TO MOVING THE R CONDITION LEVER TO THE FUEL OFF POS. THIS ACTION WAS TAKEN IN ORDER TO SATISFY THE QRH CHKLIST FOR A PROP OVERSPD. THE QRH CHKLISTS FOR ENG SHUTDOWN AND FOR 1 ENG INOP LNDG WERE THEN COMPLETED. DUE TO THE NOW SINGLE ENG OP, AN EMER WAS DECLARED WITH THE ZMP CTLR, WITH A REQUEST FOR DSCNT. OUR POS AT THE TIME OF THE FAILURE WAS APPROX 20 MI S OF MCW. AT THE TIME OF FAILURE, WE HAD JUST EXITED A CLOUD LAYER, AND OUR FLT CONDITIONS WERE VMC WITH A SCATTERED TO BROKEN LAYER BELOW. THE MCW ARPT WAS FIRST ACQUIRED VISUALLY A FEW MINS AFTER THE FAILURE OCCURRED. IT WAS IMMEDIATELY CLR THAT MCW WAS THE NEAREST SUITABLE ARPT, IN POINT OF TIME, AT WHICH A SAFE LNDG COULD BE MADE. I ALSO KNEW THAT CFR WOULD BE AVAILABLE AT MCW. AFTER THE APCH BRIEF, I TOOK CTL OF THE ACFT AND FEW A VISUAL APCH TO RWY 35 AT MCW. EXCEPT FOR THE SINGLE ENG CONDITION, THE LNDG WAS NORMAL. AS I TURNED OFF AT THE END OF THE RWY, THE FO CALLED ZMP AND INFORMED THEM WE WERE ON THE GND AT MCW, AND IFR WAS CANCELED. I THEN TOLD THE FO TO ASK THE EMER VEHICLES TO FOLLOW US AS WE TAXIED BACK TO THE GATE, WHICH THEY DID. UPON VISUALLY INSPECTING THE R ENG AFTER SHUTDOWN, A LARGE AMOUNT OF OIL WAS NOTED COATING MOST OF THE R ENG NACELLE, AND OIL WAS DRIPPING FROM THE FORWARD END OF THE ENG NACELLE. ALSO, DURING POSTFLT INSPECTION, THE R TIRE WAS NOTED TO BE FLAT, POSSIBLY DUE TO ASYMMETRIC BRAKING WITH THE L ENG AT GND IDLE. TELEPHONE CALLS WERE MADE TO ACR DISPATCH AND TO ACR MAINT. THE FAILURE AND FLAT TIRE WERE ENTERED INTO THE ACFT'S MAINT LOG. PREFLT ACTION: PRIOR TO DEP FROM ZZZ, THE FO NOTED DURING PREFLT THAT THE R PROP RESISTED ROTATION WHEN TURNED BY HAND. I WENT OUTSIDE TO INSPECT IT MYSELF, FOUND THIS TO BE TRUE, (SMOOTH, QUIET RESISTANCE), AND NOTIFIED MAINT IN ZZZ. THE ON-SITE ACR MAINT PERSON IN ZZZ COMMENTED THAT HE HAD NOTICED IT EARLIER AS WELL AND SAID, 'LET'S RUN IT,' TO CHK ITS OPS AND INDICATIONS. THE R ENG WAS THEN RUN (STARTED, PROP BROUGHT OUT OF AND BACK INTO FEATHER, AND SHUT DOWN), 3 TIMES BEFORE DEP -- ALL 3 WITH NORMAL PROP BEHAVIOR AND NORMAL ENG AND PROP INDICATIONS ON THE ACFT'S GAUGES. WE HAD SEEN AND SPOKEN WITH THE ZZZ MAINT PERSON UPON ARR AT THE ACFT APPROX 20 MINS PRIOR TO DEP. LATER, 5-10 MINS BEFORE SCHEDULED DEP FROM ZZZ, WHEN WE INITIATED THE DISCUSSION ABOUT THE R PROP WITH THE ACR MAINT PERSON, IT WAS NOT EVIDENT THAT THE MAINT PERSON INTENDED TO NOTIFY THE FLC, BEFORE THE FLT DEPARTED, OF HIS PRIOR KNOWLEDGE OF THE R PROP'S RESISTANCE TO ROTATION. DURING THE DAYS AFTER THIS FAILURE, I DISCUSSED THE EVENT WITH ACR MAINT PERSONNEL IN THE ENG SHOP IN THE ACR MAINT HANGAR. I WAS TOLD AT THAT TIME THAT SIMILAR FAILURES HAD OCCURRED ON THIS ENG/GEAR BOX MODEL. FURTHER, I WAS TOLD THAT GEAR BOXES OF THIS MODEL PRODUCED BY A PARTICULAR VENDOR WERE SPECIFICALLY MORE LIKELY TO FAIL IN A MANNER SIMILAR TO THIS ENG AND THIS FAILURE.

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.