Winter Flying issues

[AdamZ]

I just picked up an FAA Aviation Safety Pamplet on winter flying at a Wings seminar. There are two things that I have questions about.

1) They suggest when preflighting in winter to pay particular attention to the Crankshaft breather. They said in winter with heating and cooling vapor can condense and freeze in the line create pressure which can blow off the oil filler cap the resultant problems are numerous incluing fire and oil loss.

-My question is what the heck is a crankshaft breather
-How do I check this on preflight? Perhaps I could get to it in the Tiger but in the Archer III I can't get to anything under the cowl. The pamphlet made this seem pretty important.

2) The same pamphlet when talking about the different types of carb ice said to prevent carb ice do the following:
-use heat ground check
-use heat in the icing range
-use heat on approach and decent

The last of these concern me because the POH in the planes I fly do not state that carb heat should be used on approach and Landing. I understand that some of the Cessnas do but not the Tiger or Archer. I think the FAA should not have made such a blanket statement, but I'm not sure how to bring it to my attention.

Thanks in advance for your responses.

 

[bbchien]

I just picked up an FAA Aviation Safety Pamplet on winter flying at a Wings seminar. There are two things that I have questions about.

1) They suggest when preflighting in winter to pay particular attention to the Crankshaft breather. They said in winter with heating and cooling vapor can condense and freeze in the line create pressure which can blow off the oil filler cap the resultant problems are numerous incluing fire and oil loss.

-My question is what the heck is a crankshaft breather
-How do I check this on preflight? Perhaps I could get to it in the Tiger but in the Archer III I can't get to anything under the cowl. The pamphlet made this seem pretty important.

2) The same pamphlet when talking about the different types of carb ice said to prevent carb ice do the following:
-use heat ground check
-use heat in the icing range
-use heat on approach and decent

The last of these concern me because the POH in the planes I fly do not state that carb heat should be used on approach and Landing. I understand that some of the Cessnas do but not the Tiger or Archer. I think the FAA should not have made such a blanket statement, but I'm not sure how to bring it to my attention.

Thanks in advance for your responses.

Look at this NTSB report and you will understand. There is always gas leaking by the rings, and if not vented the Crankcase will pressurize. The C310 had a change in breather tube type that resists ice over a bit better (combustion gases contain MOISTURE) but the "safest" design is a matter of empirical trial- too long and it freezes. To short and it doesn't vent into the airstream well. This young pilot was a tad cocky and pressurized both his cases, losing power, then the shaft seal blew and sent all his oil overboard.

Two engines here meant twice the chance for idiocy.

 

[AdamZ]

But Bruce how do I as a Single Engine Piston Driver check the Breather tube? I assume I would check it for ice in the breather or accumulated moisture. The crankcase breater was never discussed in any of my training.

 

[bbchien]

The only way to do that is to see the breather tube as depicted and specified in the maintenance manual and see that it is, on the aircraft, as it appears in the manual. I can see mine through opened cowl flaps.

 

[Let'sgoflying!]

Here is a pic of one (if its not in this particular engine, then this is what they look like). They can appear in different spots but usually the arise from the top of the crankcase, pass aft and over the engine to the firewall via a flex hose, and then go down the firewall as solid pipe again, exiting out the bottom of the cowl. On preflight in many planes you might not be able to see anything except the last 4" as it exits the airplane. Make sure the opening is clear of obstructions.
Next time the cowl is off, have a look at it. Many require a cut to be made into the tube and one part of the cut bent inwards to prevent blockage in the event the end ices up, check for this opening.

 

[gismo]

WRT crankcase breather icing, prevention is far more important than preflight checking IMO. Chances are that unless you are using an airplane that's been on the ground less than 30 minutes, any breather issues you encounter will begin after some time in the air and a preflight check for ice in the line wouldn't be likely to prevent the problem (even if you could check it easily). For prevention it's common to insulate the breather line where it passes through unheated air (above the cylinders). The below cowl exit is the other place where cold air might facillatate ice blockage, but usually there is enough hot air exiting the cowling where the breather comes out that it won't freeze unless the OAT is way cold (-30 F and below). Those optional winter baffles (sometimes called winter fronts) are another preventative measure as they increase the temps under the cowl which makes ice formation unlikely.

And IME carb icing is less likely when the OAT is really cold (below +10 F) and it's possible to increase the potential for carb ice if you apply heat below that temp unless your hot air source is really hot.

I live in a northern part of the country so when I say cold I'm not talking about the balmy 30-50F that causes shivers for folks living in warmer lattitudes. It may be that the carb head information you read was aimed at the cold weather wimps down in Texas. OTOH, breather ice is rare even up here in Minnesota, but the operators in northern Canada and Alaska are typically very aware of the phenomenon.

 

[poadeleted20]

-My question is what the heck is a crankshaft breather?

A tube leading from the crankcase to the outside air allowing equalization of pressure inside the case thus preventing overpressure blowing out the oil system.

-How do I check this on preflight?

Look up the tube with a flashlight. On the Grummans, it's an aluminum tube about 3/4-inch in diameter sticking out the bottom of the cowling through the left cooling air outlet ramp.

2) The same pamphlet when talking about the different types of carb ice said to prevent carb ice do the following:
-use heat ground check

Always ground check carb heat.

-use heat in the icing range

Not at cruise, takeoff, or full-power climb unless I'm getting carb ice symptoms.

-use heat on approach and decent

Depends on the plane. This is part of the book on the Cessna family, but not on the Grummans, and for the Grummans, I recommend using only on an "as required" basis, i.e., when symptoms of carb ice are occurring.