The rear engine would generate enough heat to keep the rear breather from freezing

After inspecting the rear engine area with Larry, I retract the statement above. We think that the rear breather could freeze.

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.

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

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.

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.

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.

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.

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

just looking at stuff and came across Cessna Service Bulletin ME79-2 which may have a bearing on this accident. It addresses use of Prist or Isopropyl Alcohol as a fuel additive in very cold conditions.

My two cents worth...
 

The pilot's observed decline in oil temps followed by loss of pressure, caught my attention; as has the resulting discussion of possible oil loss. I'll offer my two-cents worth: one for each engine.

I had an oil separator installed on the rear engine of my '69 T337. Twice during long (3+ hour), high altitude, winter-cold cross-country legs, I lost four quarts of oil from the rear engine. The oil was literally everywhere. I finally determined that the probable cause was the breather running from the separator to where it vents by the prop had frozen, pressurizing the case and forcing oil out every available seal, gasket and orifice. It seems like there is or should be an alternate vent to atmosphere, but perhaps it was covered or plugged. At any rate, because it happened twice, I removed the oil separator, insulated the breather line and never had the problem again. I can't swear, however, that I again flew in as cold of temps.

The only oil anomaly I've ever had with the front engine was the result of the oil fill cap not being reinstalled properly after adding oil. The cap came off in flight (retained by its chain), and the engine proceeded to dump three-plus quarts of oil out the breather tube, completely coating the belly of the a/c. This occurred during a high altitude three-plus hour cross-country leg, but it was not particularly cold.

Like everyone else, I was relieved to hear that all were safe.

Allen

Two more cents
 

I was speaking to my mechanic about this failure, so these are really his two cents: he suggests it is oil flow problem due to congealing (at the cooler, presumably?). Seems to make some sense given the temp indication followed by the pressure indication (followed by the failures)

Winter problems
 

I to installed M-20 air/oil seperators on my 337H 6 years ago. This was due to a oil slick found on the belly and tail area. I also insulated the breather line from engine to M-20 including M-20 down the exit pipe on both engines. My rear engine always ran much hotter than the front engine, which is normal for 337. In summer I fly with cowl flap door partially open when tempature above 85 degree. In winter rear runs about 180-200 degree. The front engine runs 180-200 in summer but ran 160-170 in winter. I now install a plate above front engine oil cooler for winter to get the engine above 180 degree. Without the plate I was holding water in oil and could see droplets on dip stick. No problem now with plate installed. My bird is normally asperated so anything above 13,000 feet is out of the question and I live and fly in Pennsylvania and mostly fly 500 mile radius of Pa, so I do not experiance any super cold air.

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

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

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 ?

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

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.

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

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.

Cold Weather Equipment
 

In the POH of my 1968 Super Skymaster (lots of emphasis on the SUPER) Section VII on Optional Systems contains "Cold Weather Equipment" and says:

WINTERIZATION KIT.
"For continuous operation in temperatures consistently below 20 degrees F, the Cessna winterization kit, available from your Cessna Dealer, should be installed to improve engine operation. The kit consists of two baffles for the front engine, one baffle for the rear engine, and crankcase breather insulation for both engines. Once installed, the crankcase breather insulation is approved for permanent use in both cold and hot weather."

Attached is a photo of the front baffles but I have never seen the rear engine baffle. The rear engine baffle is attached to the lower outside ring below the prop on the exit end of the airflow. This statement is pretty standard in most all the Cessna piston Pilot handbooks except for the Turbo models. Maybe the Turbo models generate enough heat and do not require this?

I'm just curious about one thing, why did you choose that time of year to make the trip? It seems to me making the trip in the middle of summer would far outweigh making it in the winter.

hharney, thanks for the info. It seems like there should be a limitation of -20C posted in the operator's manual unless the winterization kit is installed. But now that I know the nomenclature it is figure 83A in the maintenance manual for 65-69' models. There is also a placard figure 1 for "remove winterization kit for temps above -20C." It seems to me like the placare should say "install winterization kit for operations below -20C". What's everyone else's thoughts? Perhaps a new AD is required!


================================================== ================
"In the POH of my 1968 Super Skymaster (lots of emphasis on the SUPER) Section VII on Optional Systems contains "Cold Weather Equipment" and says:

WINTERIZATION KIT.
"For continuous operation in temperatures consistently below 20 degrees F, the Cessna winterization kit, available from your Cessna Dealer, should be installed to improve engine operation. The kit consists of two baffles for the front engine, one baffle for the rear engine, and crankcase breather insulation for both engines. Once installed, the crankcase breather insulation is approved for permanent use in both cold and hot weather."

Attached is a photo of the front baffles but I have never seen the rear engine baffle. This statement is pretty standard in most all the Cessna piston Pilot handbooks except for the Turbo models. Maybe the Turbo models generate enough heat and do not require this?"

hharney, thanks for the info. It seems like there should be a limitation of -20C posted in the operator's manual unless the winterization kit is installed. But now that I know the nomenclature it is figure 83A in the maintenance manual for 65-69' models. There is also a placard figure 1 to "remove winterization kit for temps above -20C." It seems to me like the placard should say "install winterization kit for operations below -20C". What are everyone else’s thoughts? Perhaps a new AD is required!

One final thought, Cessna called it a winterization kit...but I'm flying in the winter without it. So perhaps it should be call the extreme cold weather kit...-20C is extreme cold weather. I really think Cessna went out of their way to ignore the whole -20C operation.


================================================== ================
"In the POH of my 1968 Super Skymaster (lots of emphasis on the SUPER) Section VII on Optional Systems contains "Cold Weather Equipment" and says:

WINTERIZATION KIT.
"For continuous operation in temperatures consistently below 20 degrees F, the Cessna winterization kit, available from your Cessna Dealer, should be installed to improve engine operation. The kit consists of two baffles for the front engine, one baffle for the rear engine, and crankcase breather insulation for both engines. Once installed, the crankcase breather insulation is approved for permanent use in both cold and hot weather."

Attached is a photo of the front baffles but I have never seen the rear engine baffle. This statement is pretty standard in most all the Cessna piston Pilot handbooks except for the Turbo models. Maybe the Turbo models generate enough heat and do not require this?"

I purchased the aircraft in June. I planned the crossing for the end of august.Unfortunately the work on the aircraft took much longer than expected. I know that it is serious business to perform this flight during the winter and that you can easily be on the ground waiting for a weather improvement. If you are planning a flight like this make sure that you got thé right gear.I hope this answers your question.

Troels.

Great story, and an absolutley great piece of survival flying and ditching. You should certainly write it up in either short story format, or talk to somebody about a book. Make up a couple Eskimo chicks and an igloo, and you could probably pay for the plane.

I would however not jump to any conclusion about oil loss being the cause of the engine failures. It is far to much of a coincidence to have both engines fail that close to each other from a oil problem, especially in a Skymaster. The whole dynamics of the engine compartment temperatures, and subsequent temperature variations encoutered by the oil systems is too diverse to have them both encounter the same error within minutes of each other.

It sounds like plain old fuel starvation which wound down the oil pressure , which cooled down the temps, which then caused some form of noise form the prop once there was no oil pressure in the system. Maybe the big noise was the blade kicking back to feather , and that was caused by it being frozen once the rpm's starting bleeding off.

Regardless, congratulations on getting through it.

Three times I have had an engine quit in mid-flight due to fuel starvation. Ignoring the first time, when I had zero experience with the aircraft*, the indications are immediately obvious as fuel starvation. Given Troels familiarity with this aircraft and his experience, I very much doubt that this was fuel starvation.


Ernie

______________
* It was my first Skymaster flight and, while climbing, the instructor turned the fuel selector valve to off without my knowledge to demonstrate the docile behavior after a lost engine.

Does Cessna still sell the winterization kit or does anyone know where I can get an aftermarket version of it? I definatly need it flying around the Colorado Rockies in the winter.

Karl

I never forget the sounds that my engines made before they stopped.Sounds of metal against metal and great friction followed by a loud bang. I saw the low oil pressure indication before they made these sounds.To me it is very clear why they stopped.

Troels.

I don't mean to be contentious giiven your extensive experience, personal observations, and expertiese, I am only concerned that because this is an "infomrmation sharing website" that we should all be cautious about what we profess to "know for sure" when it may affect other pilots safety.

I would think that because we don't "know" what happneded to your engines, that we should keep an open mind about other possibilities such as vapor lock and/or fuel stavation, gelling, fuel pumped outboard through the vents, frozen/cracked cork fuel tank seals, etc...

I didn't notice if you ever mentioned cross feeding the tanks, before or after the engine failure. For example when the rear failed, did it make the same loud noise, and/or did it just go out for an entirely different reason, and because the front failed from perhaps an oil problem, did you assume the rear had the same problem, and there was no reason or time to try a cross feed and restart?

Not picking on you : It must have been a nightmare. Just want to make sure nonone else encounters a like scenerio and has the wrong assumptions.

Dear Roger.
I totally agree with you. For the same reason I try not to speculate or draw conclusions and just write exactly what happened and what I observed. I told my story in this forum because I was very thrilled about being a Skymaster owner and pilot. I am not trying to say that the Skymaster is a bad and unsafe aircraft. More than anybody I would like some answers to what happened to my engines,but unless the aircraft is salvaged I will probably never get any answers.I have been told that the Hudson Strait is 113 meters deep at the position we were picked up and since there is nobody in the plane it will not be raised.

Troels

Well said, but since this is an information web site, the info we've discussed is very valuable and should be taken to heart by all of us. For me personally, the -20C is a big red alarm if I'm ever flying in weather that cold...let's hope not.

So Troels, when are you buying the replacement 337? There are some great deals around!

If you can pick one up during the next couple of months, you can meet us at the 2010 SOAPA Fly-In in Branson! :-)

Paul
Do you know any good ones. I need the following.

Non turbo VAR crankshaft engines with some time left.Deicer boots.Preferably with some new garmin avionic including mode S transponder and a 406 ELT. ADF and DME is still a requirement in my country .Propellers and governors within their calender lifetime of 6 years. Magnetos within their calender lifetime of 4 years. Engine and airframe hoses within their lifetime as stated in the maintenance manual.

These are all EASA requirements and I know that finding one that meets all of them is hard since you normally dont do overhauls based on calender time in the US and so on.

I hope that I can go to one of your meetings some day and see your Skymasters.

Troels.

Troels,

It sounds like a normally aspirated 337 with engines having been overhauled within the last 10 or 15 years should do - VAR cranks should have been installed at that time.

To get a panel still equipped with ADF/DME you'll probably want an older, non-updated panel (updated panels would have removed at least the ADF), and install a 406 ELT and S XPDR. If you don't require a panel-mounted IFR GPS (and even if you do), a Garmin 496 provides amazing functionalities.

Are there life limits stated on engines? I've only heard of TBO's. Replacing the engine hoses and airframe flexible hoses isn't that big a deal, and would start you on a new 5-year cycle.

Happy hunting!

Documentary
 

Here is the link to a CBC documentary. As good as it gets, I guess.

http://www.cbc.ca/player/Shows/Shows/ID/2305885459/

Gerd

cbc
 

Not available. I guess not available to US computers.