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Alternate Air

N

NewbRVator

Well Known Member
Hi All,
I have a 6A w/ an O360 A1A but no alternate air. Stanard build. Wondering who's done it and pro's con's to adding.
Thanks
 
I don?t have alternate air. Flying for 9 years and over 5K hours never needed it. Couple of my friends have it installed. Didn?t use it yet. A matter of personal preference I guess.
 
The chance of ever needing it is very very slim but it is a redundancy thing, specially if you ever get to a possible icing situation.

It is not hard to add it but I would probably skip it if it was me.
 
I have a 6A with the same engine (but converted to IO status by the builder) and have pondered the same thing. Was originally planning to put in an alternate air arrangement when contemplating making the plane IFR-legal, but have put off the IFR thing and will probably not do alternate air unless going the IFR route.
 
12 years and 1000 hours and never installed it and never needed it.

Back when I was building, there were a number of builders who tried different methods of installing the alternate air door and everyone that I saw eventually failed.

The problem is that the failure mode means parts (rivets, bolts, washers, nuts, etc.) get sucked in and through the engine.

It seams to me that installing the Alt Air door is more likely to cause an engine stoppage than the actual need for the door.

I wouldn't install one, even if flying IFR. However, I have a real carb heat muff from Wicks. The one I used is no longer available but this one is and is similar to what I installed.
 
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On an RV, installation of an alternate induction air system has no connection to the need for or in use performance of a carb. heat system.

That is why it is recommended for fuel injected and carb. equiped engines.

Having an alternate induction air system should be somewhat considered the same as the decision of whether to fly with a parachute.
The likelihood of ever needing it is very remote. Especially if a particular airplane is never flown IFR. But if that unlikely situation should ever be encountered.........

Builders/owners must weigh the risks and decide.
 
Thanks for the responses. That's kinda what I thought. I'll be extra careful not to leave a rag in the snorkel.:D
 
Kuhtenia said:
I have a 6A with the same engine (but converted to IO status by the builder) and have pondered the same thing. Was originally planning to put in an alternate air arrangement when contemplating making the plane IFR-legal, but have put off the IFR thing and will probably not do alternate air unless going the IFR route.
Click to expand...

Unless you have non-standard op limits, alternate air is not required by law for ifr. That said, as Scott has already said, it only takes one time when you wish you had it. The -10 design, if backed with a metal ring, not fiberglass, inside the airbox, seem relatively immune to FOD.
 
To me the risk of sucking in a plastic grocery bag right around take off doesn't seem astronomically high, given how many I see blowing around on streets on a windy day. Getting one sucked in would make for a really bad day. The design isn't really that bad and with some thoughtfull adjustments, it can last for a long time without risk of sucking parts into the engine, if the vacuum is even strong enough to pull them up a foot or so.

I would never fly IFR without one due to ice concerns.

Larry
 
I've had plenty of aircraft come in with the alt air hardware and door missing on the vertical induction setups.

I run FI with vertical induction on my 7, no alt air, don't fly in icing conditions. The carb heat door is still there if I ever decide I like winter flying in ice/snow (not likely).

In the unlikely event you suck a bag up on take-off, I seriously doubt you will have time to sort it out and pull the alt air control.
 
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