Skymaster Arctic Circle Ditching.

[Diamond Service]

The forward engine failed first. This engine was factory new in 2000 and had been running 470 hrs since then. 5 minutes later the rear failed. The rear engine was Mattituck overhauled in 1996 and had a little more than 800 hrs running time since the overhaul.The rear has breather outlet just behind the prop. I saw no oil on the windshield.

I know that Continental is now working with The Canadian NTSB on the subject.

Troels.

[CO_Skymaster]

I bought my 1966 Skymaster 2 year ago, and with all used machine there were some repair to be done. I notice that when the aircraft sat after flying, small pools of oil would appear under the front wheel well and also when dropping my gear doors, oil was in there also. I asked my A&P about it and his response was that the seals on Continental engines tended to leak and there wasn't much I could do about it except to keep adding oil. My engines have about 2200 hours each, so at the time I took him at his word. Besides, I had other repair to work on.

Last Christmas, I flew from Colorado to California to test the aircraft after my repair had been made. The trip out to California was uneventful as was the scenic flight for my friends around the San Francisco bay area. On the way back to Colorado, I landed in Nevada for refueling. Didn't notice anything out of the ordinary. It was already cold (about 25 degree F on the ground) when I took off again. Over the Utah/Colorado boarder I passed through a cold air mass I was expecting and my OAT drop from 20 deg F to below -15 deg F in about 20 minutes. It was so cold, my heater could keep me warm and I had to put on my winter coat, which was in reach (I couldn't reach the gloves which were way in the back). By the time I landed in Colorado Springs I found my rear spinner cone and broke off and there was oil all over my horizontal stabilizer.

Besides the spinner cone being a pain (I mention it somewhere in the messages), it turns out those seal used on my valve covers started leaking and my oil just passed out past the propeller and out the back. I lost 4 quarts of oil during that flight. If I continued the flight, I would have lost it all. After fixing the seals, I have had any pools of oil leaking anywhere.

I wonder if flying into very cold weather with degraded valve cover gaskets allows oil to leak out of the engine and it just flow along with the airflow out the bottom of the aircraft on the front engine and out past the propeller for the rear engine. There would be no visual confirmation. You won't see an oil pressure drop until your almost out of oil and you never see a temperature rise in the oil (because there is less of it to absorb heat) or Cylinder head temperature rise due to the extremely cold weather. When all the oil is gone, your engine seizes.

Just my opinion at this point. I've included a picture my friend took of my front nose wheel and you can see the oil around the chocks. It doesn't do this anymore.

Karl

[John Hoffman]

I have had the Skymaster 10 yrs now and engine leaks have mostly been the gaskets under the valve covers. At some point they were discovered to be poorly installed and old so I had them all replaced. Leakage has been nearly zero. The new ones did require some retightening a couple of times, probably due for a check agin. Have had some minor leaks of the gaskets you describe but not a problem.

[Skymaster337B]

If the valve covers required safetywire to lock the nuts down, then we wouldn't have this discussion. I've used RTV on these gaskets and find that helps alot.

[Diamond Service]

Hello Karl.
Thank you very much for sharing your expirience. All information like this help me to find answers and to heal my wounds. I am quite sure that my engines had the red silicone seals under the valve covers. I need to look in a computer in my maintenance shop for the pictures.

Rgds Troels.

[ipasgas1]

I, too, had an engine failure but in a single engine aircraft. It had a Rotax 912ULS engine. But, I have often wondered if the cold had something to do with the failure. The NTSB and Rotax said it was due to oil starvation due to a "collapse" of an oil hose. It was MLK day, 4 years ago, and happened to be the coldest day of the year, around 0 degrees F on the ground. I had no warning of the impending failure, it was sudden and finite. The extreme cold sounds like a very likely culprit. I now fly a skymaster for the added engine but I still, and moreso after this, will not fly in extreme cold.

[Dave Underwood]

A thought on being prepared.

When I used to fly in Northern Ontario I was always reminded to be prepared and to make sure I could survive with only what I had on me as I got out of the plane. The reasons were simple. The float plane could sink or the aircraft could go up in flames.

These days with portable transceivers, Personal Locator Beacons, cell phones and multitools with powerful LED lights it is much easier.

Perhaps we should all consider what we need to have on us in that very worst case.

Can I also wish everyone a Very Merry Christmas and a Great New Year with bright blue skies and more reasonable gas prices.

Warm regards - Dave