Perhaps this is a dumb question, but I was watching IFR flight videos on PilotWorkshops, and videos showed the pilot closing the ram air intake door and opening intake alternate air when flying in the rain. This was on carbed Lancair. Is this "standard protocol"? I've never read this before, and wondered if flying in rain would somehow affect the air filter flow, etc. I've flown in light rain with no issues, but nothing more.
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When to close ram air ?
- Thread starter edhunter
- Start date
Majorpayne317641
Well Known Member
Negative… unless this is specific to that aircraft/engine combo.
Vans alternate air doors are not really designed to be reset once pulled. Some people have modified them to open and close without taking off the cowl.
Not sure about the paper filters but cloth filters like K&N don’t care if they are soaked for this engine/CFM airflow combo.
I’ve flown in rain heavy enough that you couldn’t hear anything over the sound of rain on the wind screen. The engine runs fine in rain and more than likely ingested water. So long as there is still room for combustion it will keep going. I do notice a TAS reduction but that may be a combination of things not just the engine while flying in heavy rain.
Vans alternate air doors are not really designed to be reset once pulled. Some people have modified them to open and close without taking off the cowl.
Not sure about the paper filters but cloth filters like K&N don’t care if they are soaked for this engine/CFM airflow combo.
I’ve flown in rain heavy enough that you couldn’t hear anything over the sound of rain on the wind screen. The engine runs fine in rain and more than likely ingested water. So long as there is still room for combustion it will keep going. I do notice a TAS reduction but that may be a combination of things not just the engine while flying in heavy rain.
The alternate air door was added to RV airboxes after a fatal RV-6A accident that ingested snow and the engine was not making full power. Going from memory, the alternate air door was intended as a way to prevent engine stoppage when the filter became clogged. The airplane was on an IFR flight at night and encountered snow. ATC gave them vectors to the nearest airport (KIYK) but the airplane impacted high terian on the way to the airport.
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I too have flown through heavy rain shafts, mostly for a quick airplane wash. 4" horizontal intake, K&N 33-2124 flat filter, no engine issues.
As Gary said, the issue is snow, ice, or a plastic bag blocking the filter face. I built a spring loaded alt air door which doesn't require any pilot action. A microswitch trips a cockpit LED if it's off its seat.
As Gary said, the issue is snow, ice, or a plastic bag blocking the filter face. I built a spring loaded alt air door which doesn't require any pilot action. A microswitch trips a cockpit LED if it's off its seat.
