Did you install an Alternate Air control?

N941WR · #1 02-05-2009, 02:27 PM

The question was asked in another thread how many of you installed alternate air control and I thought I would make a poll out of the question.

cwreeves · #2 02-05-2009, 02:43 PM

My first thought was this thing is just something else to install that will loosen up and have to be fixed but I installed it after much soul searching. It wasn't a big deal and didn't take much time. I just figured Van's had a good idea and there really isn't much can go wrong with it.
Charlie, Tucson AZ

Greg Arehart · #3 02-05-2009, 06:32 PM

There were some posts here in the last year or so indicating some potential weak points in the standard installation, plus, once pulled you have to get on the ground and take off the cowl to close it up again. So I manufactured my own system, which is basically a sliding door system that can be opened AND closed from inside the cockpit.

greg

hgerhardt · #4 02-05-2009, 07:46 PM

Spring-loaded flapper door on the inboard side of the FF snorkel. Made the whole thing out of fiberglass. Made it long before Van's came out with their kit.

Never tested it with a clogged filter. I suppose I should block the filter one of these days and see if the engine will run WOT with the tail tied down.

Heinrich Gerhardt

L.Adamson · #5 02-05-2009, 08:29 PM

Of course I did. The more weight the better! And it's just one more knob to go with my blue knob...

L.Adamson ---RV6A

Bob Brown · #6 02-05-2009, 08:50 PM

I always figured if I ever have to pull it open, I won't care about closing it in flight, It'll be a bona fide emergency...in fact, I'll probably be so excited I'll pull so hard it will rip the the cable off the door...

Bill Wightman · #7 02-05-2009, 09:32 PM

No alt-air control here. IO360 with snorkel of my own design and filter in front of the left front cylinder.

I'm hoping that the DAR who does my airworthiness inspection doesn't have any problem with the lack of alt-air.

Have any of you had problems with FAA-DAR's squawking your plane for NOT having alt-air???? I hope not!

Greg Arehart · #8 02-05-2009, 11:17 PM

I recently had the inspection and was told by the inspector that he has "nothing to do with design" that "you could put a jet engine on a barn door with a shovel" and he could not disapprove of it from a design standpoint. Seems that the main thing he was looking for was whether there were enough threads on the bolts past the nuts and stuff like that. So my take is that the presence or absence of an alt air door would probably be irrelevant (at least from the perspective of the FAA inspector). Depending on your inspector/DAR, they may see this issue differently.

My nickel's worth (used to be 2c but up on account of inflation...)

greg

asav8tor · #9 02-06-2009, 12:43 AM

This comes up from time to time and there are a whole lot of opinions on having an alt air door. Sometimes posters will come up with an idea or improvement for increasing the safety factor for a problem that has never happened in the RV fleet. Then the alt air door subject comes up and there are many negative comments about the need. Fact is several RVs have gone down and fatalities have resulted from engine stoppage when an alt air source could have saved the airplane and pilot/pax. I witnessed one of them.

By the way, I can reach up from the lower cowl outlet and reach the alt door to close it without taking the cowl off on the 4.

kiwipete · #10 02-06-2009, 05:36 AM

Having had an engine stop through a blocked filter in a twin, I wouldn't dream of not fitting one. (One of the engines Alt air didn't work )
An hour or two's work over the whole project is nothing and is worth it for the peace of mind.

Peter