alternate air?

[larrys]

Building a 14 with a Thunderbolt motor. I am doing the snorkel now and it says to do an alternate air plate. I am inclined not to do it. But what are the pros and cons? I do not understand why it is provided and a couple of plan pages are dedicated to it?
Hope you guys can fill me in.
Thanks, Larry

[JonJay]

Do a quick search for the never ending debate.

[Tom Martin]

I found it not difficult to install and you would really not what to be in the, I should have done that group.
It is a lot easier to now then retrofitting later.

[kbalch]

Why wouldn't you want to install the alternate air door? Having one can be a real lifesaver and it's easy to do, especially during the initial build.

[Bavafa]

Originally Posted by kbalch

Why wouldn't you want to install the alternate air door? Having one can be a real lifesaver and it's easy to do, especially during the initial build.

Plus one for this comment

[Discus2b]

Has alternate air ever been needed?
R

[N941WR]

Originally Posted by kbalch

Why wouldn't you want to install the alternate air door? Having one can be a real lifesaver and it's easy to do, especially during the initial build.

Because many of them have shed parts which have been sucked into the engine.

For those who say it will save their life on takeoff, should they ingest a plastic grocery bag on takeoff, I say they won't have time to diagnose and resolve the problem before the crash.

925 hours without one and counting.

[Tom Martin]

The design of this one reduces the possibility of parts injection greatly. All moving parts are outside the air box unlike the old doors on previous models.

[lr172]

Originally Posted by N941WR

Because many of them have shed parts which have been sucked into the engine.

For those who say it will save their life on takeoff, should they ingest a plastic grocery bag on takeoff, I say they won't have time to diagnose and resolve the problem before the crash.

925 hours without one and counting.

Just like a fire extinguisher. I am sure some choose not to carry one because they have never had a fire in 925 hours. We are fortunate in this hobby that each individual can set their own risk tolerance and equip accordingly. Op should set his own risk criteria. It can be dangerous looking for consensus on these types of decisions.

Frankly, I am more concerned with water saturation and ice than garbage bags. But hey, if you never plan on flying in ice or rain, it shouldn't be a problem Not sure how the K&N will tolerate it, but I have had a auto engine stop running due to a water logged paper air filter.

IMO there is no benefit to not installing this beyond the 45 minutes saved. On the flip side, it could save your life, regardless of how remote the probability is. If you fly IFR, this is as essential as pitot heat IMO. Though you will find plenty of folks that say they are not necessary because they never experienced an iced over pitot.

Risk of ingesting parts of the assembly can easily be addressed by using thin aluminum sheet under the shop head of the rivets.

Larry

[mturnerb]

It's too easy to do NOT to do it. The design limits risk of FOD ingestion and it's only going to happen if you need to open the door anyway. And if you need it FOD is the least of your concerns.

A no-brainer IMHO.