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What is the function of the pipe referred to as "Venting Pipe" in the picture and how is it different from the exhaust pipe? The two photos you see in the picture are the "Venting Pipe" and "Exhaust Pipe" of the DA40NG aircraft, respectively. The exhaust pipe is in the lower right part of the cowling of the aircraft, but this pipe is located in the lower left part of the cowling, and there is a gascolator structure between these two pipes. What is the function of the "Venting Pipe" in this picture that I took a screenshot of and how is it different from the "Exhaust Pipe"?

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    $\begingroup$ That's the breather line I was mentioning on the post about cold weather. If it doesn't have an alternate exit for winter ops, it can freeze over. There was a Cirrus that went down in the North Atlantic on a ferry flight when it ran out of engine oil just S of the Greenland coast. The pilot wore a summer sailing dry suit, not a proper immersion suit, and he died of the cold water just before a helicopter which just happened to be about 45 min away from his pos, reached him. The family sued Cirrus claiming the breather had not been winterized with an alternate port. Dunno how it turned out. $\endgroup$
    – John K
    Mar 14, 2023 at 2:33
  • $\begingroup$ I think there was an engine oil problem due to freezing. But I couldn't understand what this has to do with the breath system. Was there an oil problem in this accident because the breath system did not work due to the freezing? Is this the quote you're talking about? = "To protect the breather system from blockage due to icing of moist blow by gases an engine integrated over pressure valve is provided below the injector cover." $\endgroup$
    – pilot162
    Mar 14, 2023 at 9:11
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    $\begingroup$ Exactly. Without that, ice can form right at the breather outlet until it covers it over. All that combustion blow-by going past the piston rings into the crankcase has to go somewhere, so it forces its way past the next easiest exit, usually the main crank seal behind the propeller. It may take a couple of hours to push enough oil out that seal, and all over the windshield, to finally unport the engine oil pump suction line, but eventually you have a glider. $\endgroup$
    – John K
    Mar 14, 2023 at 12:55
  • $\begingroup$ Got it, thanks for the example. I hope the deceased pilot rests in peace, unfortunately the aviation rules are written in blood. $\endgroup$
    – pilot162
    Mar 14, 2023 at 13:39

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The “venting pipe” vents engine crankcase gases outside the aircraft. In the service manual it is called the “drain collector”.

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  • $\begingroup$ Thank you so much, captain! $\endgroup$
    – pilot162
    Mar 13, 2023 at 14:56
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    $\begingroup$ Cars have that too, but it's recirculated into the air intake via the PCV valve, so it's not a separate exhaust pipe. $\endgroup$ Mar 13, 2023 at 23:04
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    $\begingroup$ And if you have a newer car with gasoline direct injection, crankcase goo builds up on the intake valves until the engine starts to run terribly and you have to take it in to have the intake manifold removed and the valves walnut shell blasted, for a thousand bucks. For this reason I stick to Toyotas and Fords, which have a dual GDI/Port system. $\endgroup$
    – John K
    Mar 14, 2023 at 2:27

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