Skymaster Arctic Circle Ditching.

sunnysky · #1 01-07-09, 05:21 AM

BILLSHEILA is on the right lines I think.
Several years ago I was flying my 337G from France to the UK. It was a much much colder than ISA day. Seem to remember something like minus 20c at 12000feet. We had been in the cruise for over two hours when I noticed the rear engine oil temp gauge "going off the clock". The problem was confirmed by low oil pressure. I reduced power on the rear and started a descent. The intention was to divert to Cardiff in Wales. At about 7000feet the oil temp started to reduce together with an increase in pressure. Power was gradually increased and the engine ran normally and the flight continued to Leeds Bradford.
I reported the problem to the Chief Engineer at Knight Air ( who were very "au fait" with the 337 ) and we concluded that there is a thermo valve in the oil cooler which stops oil going thro' the cooler when cold. In this instance because ambient was minus 20 or so, the cooler had shut off, then causing the oil to overheat then the low pressue. If there is then congealed cold oil in the cooler, the valve will not open to let the hot oil through. Then overheating. The only reason oil started to flow thro' the cooler again was due the the rise in ambient temperature.
Hope all this makes sense.!! It's my input for what its worth !!
Sunnysky

Ernie Martin · #2 01-07-09, 10:19 AM

The report, however, is that they had a decrease (not increase) in oil temperature, which differs from your experience. Might be the same issue if oil temp was measured at the cooler in their aircraft and in the engine in yours.

Ernie

sunnysky · #3 01-07-09, 10:39 AM

Hmm. Must say I didn't understand the bit about decreasing oil temperature in their report. Usually when you have decreasing OIL PRESSURE (as they state) you have a high oil temp ?
Maybe some clarifacation on the oil temp situation would help.
Your point Ernie on on where the oil temp is sensed. Surely its the same in all 337s ? Apart from the turbo ones maybe ?

Ernie Martin · #4 01-07-09, 02:34 PM

I assumed the same, that all 337s measure oil temp at the same location, BUT a different measuring point seems the only way that your experience and theirs has the same cause. Also, is it possible that electronic engine monitors put the probe at a different point than the stock gauges?

Ernie

Skymaster337B · #5 01-10-09, 09:35 PM

I'm starting to like the oil cooler theory. My question is, what type of oil was used? Straight weight or multi-viscosity synthetic oil? Personally, I only use synthetic oil and it makes a big difference how fast the oil pressure rises on a very cold day.

I also find it rather odd that the operator and maintenance manuals don’t establish a cold weather limitation…they both generally discuss colder weather starting procedures. There is an option for an oil dilution system, but that is for starting during cold weather and not while operating at altitude. The operator's manual says to watch engine temps during a cold weather descent…i.e, don’t chop the throttle. But the big paradox is I remember seeing optional cold weather plates the restrict airflow thru the front cowl and also out the rear cowl…but can’t find any info about it in either the operator or maintenance manual. It makes me wonder if Cessna really didn’t even want to mention cold weather flying for some reason.

sunnysky · #6 01-11-09, 02:23 AM

Yes. I;ve heard about "winterisation" kits, but can't find out much about them.
Sunnysky

Diamond Service · #7 01-11-09, 04:41 AM

The aircraft just had an annual done. The DAR can not issue an export C of A unless the annual is no more than 30 days old. The magnetos,prop governor and propeller were overhauled on both engines. The engines was serviced with Aeroshell 15W50.

During the cruise at 11000 feet the oil temperature was pretty much in the middle of the green arc. I was not concerned with the OAT being -30C since I have flown several pressurized twin Cessnas and Malibu 310 in colder conditions.

I did two test flights in Ohio. Some oil was noticed on the prop blades and I discussed it with the owner of the maintenance shop but we both considered it to be normal for a newly overhauled prop. We agreed that the seals in the props need some hours of operation and they will stop leaking. I did not notice any major oil leaks on the blades later on. I monitored the oil consumption on the engines very closely and they were not using much.

It feels to me like there was no oil left in the engines. The oil temperature decreased because there was no oil flowing past the sensor,but just enough to hold the pressure up a little while longer. There is a lot of ways to lose engine oil and I can only speculate. Why this happened to both engines within such a short period of time is also hard to answer.

I have more than 12000 hrs in the air. I have flown a lot of piston powered aircraft. I got my aircraft mechanic license in 1984. I am the owner of an aircraft maintenance shop that serves light aircraft. I search hard for some answers on what happened to my engines that night over the Hudson Strait. I am thankfull for all your comments but I also accept that I will probably never know for sure what happened. I want to buy another Skymaster but my family has suffered enough and for them the aircraft is a symbol of misfortune. I learned a lot from this accident. The equipment we had and the skills we had saved our life. My advise to pilots that fly over remote areas is to have the right equipment and use it. I also learned that what you have inside your suit is what you have left after a ditching. I know that the people that searched for me that night and the people that took care of me after I was saved is probably not in this forum but I want to thank them anyway. I am touched and lost for words on what they have done for me.

Troels.