Narrative:

At AB47 local time flight departed las with 8 passenger and myself on a scheduled flight to gcn via the blue-1 route through the sfar 50-2. A cruise altitude was reached of 7500 ft MSL, normal power settings and indications were noted. While in the sfar over the shivwits plateau, the right engine began to run very rough without any warning, causing a very noticeable vibration both felt and heard. Engine indications were abnormal/fluctuating. Fuel quantity indications were normal. The mixtures, propellers, and throttles were moved full forward and the auxiliary fuel pump for the right engine set to high. After a few seconds, while verifying position of magnetos and fuel selectors, the right engine was slowing down rapidly and I had a concern about not being able to feather the propeller, so the decision was made to shut it down and secure the engine. During this time I made a left 180 degree turn to remain north of the blue-1 route and reduce conflict with opposing traffic on the same route behind me at the same altitude. At this time, the first of many position reports were given to alert other aircraft in the area of our situation/intentions. I first took up a course towards a dirt landing strip on top of a mesa (pearce ferry) approximately 21 NM away and, while en route, reset power on the left engine, monitored its indications, tried 1 airstart on the right engine and contacted flight control (company) of the situation. By the time I arrived at pearce ferry airstrip (which is on the way back towards las) I was able to evaluate the aircraft's performance and felt more comfortable in its ability to maintain altitude while holding approximately 10 KTS above vyse (104 KTS). Because I was uncomfortable with the conditions at pearce ferry (dirt strip, 3800 ft long, no emergency equipment or personnel for mi away, and it sits on a mesa), I decided to continue towards las via the next smaller airport along the route, which was U30. By the time I reached U30 (approximately 3 mi north) I had attempted a second airstart, continued to talk to company and monitor the left engine. Again, the decision was made to continue to las based on the aircraft's performance, knowing there was emergency equipment at las, if required, and because I was familiar with the airport and very comfortable with runway lengths, etc. Again, I only wanted to consider U30 if things indicated they would get worse, because of the runway length (3500 ft) and no equipment I was aware of. Finally, at AC40 local time, I landed safely at las without any further incidents. It was later determined that a gear driven by the camshaft, which is connected to the governor mechanism, had sheared, causing a variation in the pitch of the right propeller. According to the mechanics I talked to, I was justified in the engine shutdown. My biggest concern, looking back on all this is, was it justifiable to return to las considering aircraft performance, runway lengths, and equipment available, or would these other airports/airstrips have been considered suitable airports.

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Original NASA ASRS Text

Title: ACFT FEATHERS 1 ENG OF A 2 ENG ACFT. FLIES BACK TO HOME BASE OVERFLYING 2 ARPTS THAT COULD ACCOMMODATE THE ACFT.

Narrative: AT AB47 LCL TIME FLT DEPARTED LAS WITH 8 PAX AND MYSELF ON A SCHEDULED FLT TO GCN VIA THE BLUE-1 RTE THROUGH THE SFAR 50-2. A CRUISE ALT WAS REACHED OF 7500 FT MSL, NORMAL PWR SETTINGS AND INDICATIONS WERE NOTED. WHILE IN THE SFAR OVER THE SHIVWITS PLATEAU, THE R ENG BEGAN TO RUN VERY ROUGH WITHOUT ANY WARNING, CAUSING A VERY NOTICEABLE VIBRATION BOTH FELT AND HEARD. ENG INDICATIONS WERE ABNORMAL/FLUCTUATING. FUEL QUANTITY INDICATIONS WERE NORMAL. THE MIXTURES, PROPS, AND THROTTLES WERE MOVED FULL FORWARD AND THE AUX FUEL PUMP FOR THE R ENG SET TO HIGH. AFTER A FEW SECONDS, WHILE VERIFYING POS OF MAGNETOS AND FUEL SELECTORS, THE R ENG WAS SLOWING DOWN RAPIDLY AND I HAD A CONCERN ABOUT NOT BEING ABLE TO FEATHER THE PROP, SO THE DECISION WAS MADE TO SHUT IT DOWN AND SECURE THE ENG. DURING THIS TIME I MADE A L 180 DEG TURN TO REMAIN N OF THE BLUE-1 RTE AND REDUCE CONFLICT WITH OPPOSING TFC ON THE SAME RTE BEHIND ME AT THE SAME ALT. AT THIS TIME, THE FIRST OF MANY POS RPTS WERE GIVEN TO ALERT OTHER ACFT IN THE AREA OF OUR SIT/INTENTIONS. I FIRST TOOK UP A COURSE TOWARDS A DIRT LNDG STRIP ON TOP OF A MESA (PEARCE FERRY) APPROX 21 NM AWAY AND, WHILE ENRTE, RESET PWR ON THE L ENG, MONITORED ITS INDICATIONS, TRIED 1 AIRSTART ON THE R ENG AND CONTACTED FLT CTL (COMPANY) OF THE SIT. BY THE TIME I ARRIVED AT PEARCE FERRY AIRSTRIP (WHICH IS ON THE WAY BACK TOWARDS LAS) I WAS ABLE TO EVALUATE THE ACFT'S PERFORMANCE AND FELT MORE COMFORTABLE IN ITS ABILITY TO MAINTAIN ALT WHILE HOLDING APPROX 10 KTS ABOVE VYSE (104 KTS). BECAUSE I WAS UNCOMFORTABLE WITH THE CONDITIONS AT PEARCE FERRY (DIRT STRIP, 3800 FT LONG, NO EMER EQUIP OR PERSONNEL FOR MI AWAY, AND IT SITS ON A MESA), I DECIDED TO CONTINUE TOWARDS LAS VIA THE NEXT SMALLER ARPT ALONG THE RTE, WHICH WAS U30. BY THE TIME I REACHED U30 (APPROX 3 MI N) I HAD ATTEMPTED A SECOND AIRSTART, CONTINUED TO TALK TO COMPANY AND MONITOR THE L ENG. AGAIN, THE DECISION WAS MADE TO CONTINUE TO LAS BASED ON THE ACFT'S PERFORMANCE, KNOWING THERE WAS EMER EQUIP AT LAS, IF REQUIRED, AND BECAUSE I WAS FAMILIAR WITH THE ARPT AND VERY COMFORTABLE WITH RWY LENGTHS, ETC. AGAIN, I ONLY WANTED TO CONSIDER U30 IF THINGS INDICATED THEY WOULD GET WORSE, BECAUSE OF THE RWY LENGTH (3500 FT) AND NO EQUIP I WAS AWARE OF. FINALLY, AT AC40 LCL TIME, I LANDED SAFELY AT LAS WITHOUT ANY FURTHER INCIDENTS. IT WAS LATER DETERMINED THAT A GEAR DRIVEN BY THE CAMSHAFT, WHICH IS CONNECTED TO THE GOVERNOR MECHANISM, HAD SHEARED, CAUSING A VARIATION IN THE PITCH OF THE R PROP. ACCORDING TO THE MECHS I TALKED TO, I WAS JUSTIFIED IN THE ENG SHUTDOWN. MY BIGGEST CONCERN, LOOKING BACK ON ALL THIS IS, WAS IT JUSTIFIABLE TO RETURN TO LAS CONSIDERING ACFT PERFORMANCE, RWY LENGTHS, AND EQUIP AVAILABLE, OR WOULD THESE OTHER ARPTS/AIRSTRIPS HAVE BEEN CONSIDERED SUITABLE ARPTS.

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.