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500B Merlyn 320

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N12LW - 500B Merlyn 320

I recently had an experience with my Commander that I would like to share with you.

While returning to Montana from Central California at 17,500' this last Thursday, my right engine started loosing a little MP. Initially, I easily got it back with just a little push of the throttle. Within a minute or so of this, it suddenly dropped about 10 inches MP, and the engine started to run rough. I still had oil pressure, and the JPI engine scanner didn't send any alarms. I looked out the right window, and saw oil all over the nose bowl. I immediately shut it down and feathered the prop.

So here I am VFR (on flight following) at 17,500' above a cloud deck over very remote Northern Nevada. I got everything stabilized, but I couldn't get any rudder trim. Perhaps with all the rain in Central California while I was there something froze up along the trim cable. The OAT was -25C. I easily maintained 16,500' with just the left engine. My GPS said I was near the McDermott airport. I've seen it from the air many times when flying my Cardinal RG along this same route. It is literally in the middle of nowhere with nothing around. There was at least a 2,000-5,000' thick layer of cold clouds between me and it, and it has no instrument approach. I reluctantly decided to declare an emergency with ATC. They wanted to vector me into the McDermott strip. My GPS said I was 45 minutes from Boise, so I opted to proceed there.

I was at the edge of the Paradise and Owyhee MOAs near V113 where two F15s were maneuvering. I had asked Salt Lake Center if Boise Approach had or could get any pilot reports of a hole through the clouds anywhere between me and their field. I wasn't looking forward to a single engine IFR approach through an unknown thickness of clouds in a plane that I had no single engine experience in. They called up the F15s and asked them if they could find a hole. Within a couple of minutes, one of the F15s formed up on my left side. I must say that it is pretty cool to see an F15 fairly close in formation with you. He split off to the left and reformed on the right side to see the feathered engine. He must have been amazed to see that the entire nacelle and that side of the horizontal tail was covered in oil. The other F15 had flown forward to look for a hole. The first one departed, and the second F15 appeared to lead me to a hole he had found. I descended making very shallow turns down through it. Thankfully the ceiling was over 5,000'.

The rest of the flight to Boise and the landing went well. I was handed off to Boise Approach who kept me all the way through the landing. They were all great to work with. The female controller even already knew about not turning into the dead engine when she vectored me for a base entry.

A fire truck followed me along the taxiway until I stopped on an FBO's ramp.  When I exited the plane, he handed me a chunk of ice that he saw fall from somewhere near the failed right engine. As I began trying to evaluate the problem, it occurred to me that the ice probably had come off the crankcase breather. If so, it had probably blocked venting causing a nose seal to blow. I found a mechanic that took me in. He spent a couple of hours cleaning the engine and looking for the problem. There was still three quarts of oil in the crankcase, so, luckily, there was no engine damage.  When I did a runup, we could see oil coming from the vicinity of the nose seal. You can't actually see it because it is behind the prop and hub. Of course that was the problem as we confirmed when we removed the prop and hub.

We got it all back together with a new nose seal late Friday night. I flew it home to Hamilton Montana (6S5) yesterday just a few hours before a new storm arrived.
 As it turned out, the engine problem was due to the plane not having a crankcase breather exiting in the exhaust stream as was prescribed by the manufacturer in 1963!  This caused the original tube that exits at the rear of the nacelle to freeze up and crankcase pressure to build until a nose seal blew. I finally found a pair of used stainless steel tubes from the old service kit and with the rest of the hardware corrected the oversite.  
This airplane handles well on one engine. The Merlyn Turbo 320 conversion's claim of a 16K' single engine service ceiling is believable.  With just me, about 100 lbs of baggage, and about 100 gallons of fuel aboard, I could have maintained my 17,000' altitude indefinitely at about 120 KIAS. ATC was very professional and ready to devote any effort to the problem. The F15s, while not expected, sure were nice to have around. The single engine landing wasn't difficult. You CAN taxi with only the left engine operating as long as you keep moving. 45-50 minutes takes a lot longer to pass when you have one shut down. A little adrenaline occasionally reminds you that you are still alive. Immediately shutting the engine down prevented any damage (we looked the turbo over and cut open the oil filter for a look see just to be sure).

The Merlyn conversion has given me a lot of confidence in the added safety of the plane when flying higher altitude direct routes over the high and rugged Montana and Idaho mountains. I used to fly along the airways to avoid the higher remote terrain. Now I save time by flying direct over it all.

This model Aerocommander is a wonderful airplane. It is comfortable in the cabin; it is stable in flight; it provides excellent visibility from the pilots' seats; and, with the Merlyn 320 conversion, allows an excellent climb out to on top conditions and a much faster cruise speed.

As soon as the new seed takes hold on my new airstrip and I get more practice with short field takeoffs and landings in the Commander, I will begin operating from it and will send you some more pictures.  

Larry Wokral
Darby, MT

Larry Wokral and daughter Stephani at Hamilton, MT (6S5)
Larry Wokral and daughter Stephanie at Hamilton, MT (6S5)
Updated instrument panelClose-up of updated instrument panel
Updated instrument panel

click on each picture to see a hi-res version

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