You know, there's an intersting line in that letter.

Pilots who foresee inadvertent flight into heavy snow, freezing rain, or icing conditions should consider equipping their filtered air box with a FILTER BYPASS.I

How can you inadvertently do something you foresaw?
 
With all this commotion, having some builders experience possible injestion of this flapper, I'm going to remove mine and glass the hole shut. I do not plan on flying into any rain or snow. Seems just to troublesome for my comfort. I haven't noticed and problems, but I often wondered if that thing was sucking open. And if it does, it is more likely to get sucked up into the engine. Seems the likelihood of plugging the filter is far more remote than sucking errant parts into my nice new engine.

JMHO

Roberta
 
Bob Collins said:
Pilots who foresee inadvertent flight into heavy snow, freezing rain, or icing conditions should consider equipping their filtered air box with a FILTER BYPASS.I
How can you inadvertently do something you foresaw?
Click to expand...
And you fly in the upper Midwest? ;)
 
I removed mine and glassed the hole shut during my first conditional inspection last month. I could tell by the wear that it was coming up occasionally.
 
I live and do most of my flying in Western Oregon. There have been countless times when we have rain on the ground and It's been snowing hard at 2500'. In my nearly 50 years of flying, I've seen a lot of Pacific Northwest weather, and I can't always predict what I might encounter enroute to a destination. The thought of something choking off my engine's supply of air is not a happy one. In much of Oregon, there isn't much under you except mountains and trees. Inspection of that flapper at each 50 hour oil change doesn't seem like a big price to pay.

Bob Severns
 
hngrflyr said:
Inspection of that flapper at each 50 hour oil change doesn't seem like a big price to pay.
Click to expand...

I made the airscoop removable, without having to remove the bottom cowl , as I've seen on a few other RV's, to make inspection easy. Since I also live in a rugged mountainous area, inspections along with the mod, will be my plan too.

I guess there is also that one in a million chance, of a prop chopped bird, stuffing the air intake closed. :D
 
L.Adamson said:
I guess there is also that one in a million chance, of a prop chopped bird, stuffing the air intake closed. :D
Click to expand...

In 250 hours over 1 1/2 years, I've had two, yes two in-flight bird strikes. One was chopped up by the prop, one inpacted the left bottom cowl about a foot from the induction opening. Chances are slightly less than 1 in a million. I have the flapper and inspect it regularly. A friend had his fall apart in short order. Fortunately eveything fell out of the cowl, except the magnet, which was stuck to the nose gear.

And Bob, you're not a wussy because you fly a tri-gear. You're a wussy because your team plays in a dome! ;)

Go Pack! (Grrrrrrrr)
 
I haven't seen the service letter

I haven't seen the service letter but the fix posted here some time ago is not going to fail - a little over kill no doubt but I think the by-pass idea is a good one. I'm one for not plugging your relief hole.

Bob Axsom
 
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Bob Collins said:
You know, there's an intersting line in that letter.

Pilots who foresee inadvertent flight into heavy snow, freezing rain, or icing conditions should consider equipping their filtered air box with a FILTER BYPASS.I

How can you inadvertently do something you foresaw?
Click to expand...

Bob,

At the risk of sounding didactical, inadvertent means unintentional. Most drivers can foresee the (we like to think remote) possibility of being involved in a motor vehicle accident and that is the reason we wear seat belts, but we certainly wouldn't involve ourselves in one intentionally, therefore, we could foresee an inadvertent accident occurring, just as those who fly IFR should foresee (the possibility of) inadvertent flight into show, freezing rain, or icing. It was a question, right?

If there are concerns about swallowing parts of the bypass mechanism, shouldn't it be made more robust?

Ken
 
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Alternate Air

I think it would be a very bad idea not to have a source of alternate air.
In fact if I was a DAR I would not find it to be acceptable without one.

I've only heard of one case (O-360, MA4-5) of the flapper blocking air to the carb and that was due to cracking along the flapper / flapper pivot shaft. In this case the pivot shaft was below the flapper, which made it easier for the separated flapper to block air to the engine.

Have a look at the ntsb records and find how many refer to carb icing or inlet icing compared to airbox failures and the choice is an easy one.
 
Beware!

If you have airflow Performance fuel injection (vertical), beware. I have removed this door from my airbox after the fourth flight. The door was installed per Van's instructions. The door opened in flight and would not close since it was being sucked into the air inlet of the fuel injection. This blocked some air into the engine, but not through the venturi, which controls the amount of fuel to the injectors. This makes the mixture rich. At a high throttle setting, it isn't noticable. When I decreased throttle at the numbers on downwind, the fuel flow rate stayed the same and flooded the engine. When I tried to increase the RPM, there was nothing there. I immediately turned for the runway and made an uneventful landing. The engine quit as I rolled to a stop. We did some ground testing and found that with the door open the engine ran Extremely rich. Without the engine data from my EFIS, I don't think we would have figured this out as easily either.

Airflow Performance was very helpful in solving this mystery and thanks go out to Jan Bussell for the excellent transition training, where we did this exact engine out scenario.
 
Air door with rubber hinge

We seem to be talking about two different setups.
I have the "new" door in the bottom of the fiberglass housing.(fuel injected, so no carb heat.) Don't see how it could block airflow unless it came off.
Some are talking about piano hinges wearing out.
Which type is giving trouble?
Mark
RV-6
 
"new" door, partial blockage

The door is right below the intake of the fuel injection/carb in the bottom of the airbox. It would swing up and hit the ring around the intake, blocking 25-30% of the opening to the fuel injection/carb. It opened about 60-70 degrees, not 90. Once it opened up, it would stay there from the suction, even at idle.
 
Bob Axsom said:
I'm one for not plugging your relief hole.

Bob Axsom
Click to expand...

Bob, That makes me more comfortable!!! Thank you!

:D

Back on topic now...

I had always planned on alternate air, ala Piper style. Why wouldn't you? It just seems logical.

:cool: CJ
 
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