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emrath(at)comcast.net
Guest

Posted: Wed May 28, 2008 6:15 pm Post subject: Fab Bypass Filter

Starting around late 2003, or so I think, Van's put out a modification for

bypassing the filter in the FAB should the filter get clogged. This is for

the vertical induction carb or FI-servo installations.  The original method

utilized a magnet and then a revised version utilized a cable operated by

the pilot.  At the time, when I first fabricated the FAB, I modified it

according to the original method using the magnet.  Today, as I finish up my

panel and get prepared to put the forward top skin on, I began thinking

about this once more.   So, I'm wondering if anyone still has the magnet

version of this modification on their ship and can tell me if the bypass

magnet releases and lets air bypass the filter under NORMAL operating

conditions or not.  I'm driving myself crazy trying to determine what the

NORMAL psi differential might be on this door to compare the calculated

force needed to open the door and the amount the door will see during NORMAL

operations.   Anyone/everyone have some thoughts on this?



Marty in Brentwood, RV6A

bobbyhester(at)newwavecom
Guest

Posted: Wed May 28, 2008 6:40 pm Post subject: Fab Bypass Filter

Marty, I did not put a bypass door in. I was told that the reason they changed from the magnet was because it was opening during normal operations. After giving it some thought I decided that I would put one in at all. I am not going to be flying in conditions that will cause the filter to ice over.

  	  Quote: 	
		  ----

Surfing the web from Hopkinsville, KY

Visit my flying RV7A web page:

http://home.newwavecomm.net/bobbyhester/MyFlyingRV7A.htm



	
 

 

 Emrath wrote: [quote]    	  Quote: 	
		  --> RV-List message posted by: "Emrath" <emrath(at)comcast.net> (emrath(at)comcast.net)



Starting around late 2003, or so I think, Van's put out a modification for

bypassing the filter in the FAB should the filter get clogged. This is for

the vertical induction carb or FI-servo installations.  The original method

utilized a magnet and then a revised version utilized a cable operated by

the pilot.  At the time, when I first fabricated the FAB, I modified it

according to the original method using the magnet.  Today, as I finish up my

panel and get prepared to put the forward top skin on, I began thinking

about this once more.   So, I'm wondering if anyone still has the magnet

version of this modification on their ship and can tell me if the bypass

magnet releases and lets air bypass the filter under NORMAL operating

conditions or not.  I'm driving myself crazy trying to determine what the

NORMAL psi differential might be on this door to compare the calculated

force needed to open the door and the amount the door will see during NORMAL

operations.   Anyone/everyone have some thoughts on this?



Marty in Brentwood, RV6A  

  

Checked by AVG. 

  	
 [b]

Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Thu May 29, 2008 3:21 am Post subject: Fab Bypass Filter

The by-pass door, with magnet, on my O-360 was opening frequently. I suspect 

on high MAP settings. It has been fixed closed. I have the cable control for 

the door but have chosen not to put in on. I think this was another CYA 

issue brought on after Van's became an employee owned business.



---

_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC

timb

Joined: 16 Apr 2008
Posts: 77
Location: Frankston, Texas

Posted: Thu May 29, 2008 3:51 am Post subject: Fab Bypass Filter

Wow, I didn't realize the door was opening under normal conditions.  How did

you determine this?  I fly off a grass runway and the thought of all that

crap getting in my engine is a bit frightening.  Also how did you (what

method) close it off permanent?



Tim Bryan

RV-6 Flying

N616TB almost 100 hours now



[quote] --

_________________
Tim Bryan
RV-6 Flying
N616TB

Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Thu May 29, 2008 4:22 am Post subject: Fab Bypass Filter

The area where the door made contact with the airbox showed signs of 

opening/closing. I semi-permanently closed it by bonding the door to the 

airbox with fluorosilicone sealant which is resistant to gasoline. You could 

do the same thing with a bit of Proseal from Van's.

I attributed my situation to the O-360 with spark advance from LASAR 

ignition which puts out a lot of power on take off. Other engine set-ups may 

not have the problem. However, if I remember correctly, Van's went to the 

cable control set-up because they also discovered the magnet was not strong 

enough to hold the door closed.

RV-6A N118DE

Dale Ensing



---

_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC

rv6n(at)optonline.net
Guest

Posted: Thu May 29, 2008 4:50 am Post subject: Fab Bypass Filter

I recently finished my condition inspection and discovered the magnet missing E 6nbsp; Obviously it vibrated off E 6nbsp; I too have received the new cable mod but refuse to put it on because it 7s design worries me E 6nbsp; The thought of a rivet 6nbsp;getting sucked into the induction system is scary E 6nbsp; So I removed the remaining parts of the original system and fiber-glassed 6nbsp;the opening closed because I would do a 180 and stay clear of weather that would call for the need of a bypass in the first place E 6nbsp; 6nbsp; Before I sign off on the inspection a simple note will be made in my POH 6nbsp;explaining why my plane should not be flown in conditions that will cause the FAB 6nbsp;to be blocked E E 6nbsp;

  6nbsp;

 Do not archive



---

mrobert569(at)hotmail.com
Guest

Posted: Thu May 29, 2008 4:58 am Post subject: Fab Bypass Filter

We found signs of the door openeing during high power setting on our IO-320.  Once I prosealed the door closed there was a very noticable increase in manifold pressure during take-offs and the engine ran much better.  We decided to leave the door closed and replaced it recently with a new FAB without a door cutout.  Much better!!

  

 Mike Robertson

 Das Fed



[quote] From: densing(at)carolina.rr.com

 To: rv-list(at)matronics.com

 Subject: Re: Fab Bypass Filter

 Date: Thu, 29 May 2008 08:18:47 -0400

 

 --> RV-List message posted by: "Dale Ensing" <densing(at)carolina.rr.com>

 

 The area where the door made contact with the airbox showed signs of 

 opening/closing. I semi-permanently closed it by bonding the door to the 

 airbox with fluorosilicone sealant which is resistant to gasoline. You could 

 do the same thing with a bit of Proseal from Van's.

 I attributed my situation to the O-360 with spark advance from LASAR 

 ignition which puts out a lot of power on take off. Other engine set-ups may 

 not have the problem. However, if I remember correctly, Van's went to the 

 cable control set-up because they also discovered the magnet was not strong 

 enough to hold the door closed.

 RV-6A N118DE

 Dale Ensing

 

 ---

brad.reak(at)verigy.com
Guest

Posted: Thu May 29, 2008 7:02 am Post subject: Fab Bypass Filter

When I built my air box (RV7A) I followed the directions and built the alternate air door with the magnet.  After flying the first 20 hours and reading that Van’s had redesigned the alternate air door, I decided that for my type of flying, the benefit of an alternate air door was non-existent but the cost of having the door open when it should closed could be high ($$$).  So I sealed the door shut and am not loosing any sleep over the decision.  

   

Brad Reak – RV7A, 70 hours.  

      [quote][b]

Terry Watson

Joined: 09 Jan 2006
Posts: 290
Location: Seattle, WA USA

Posted: Thu May 29, 2008 7:33 am Post subject: Fab Bypass Filter

I removed the door and magnetic latch and installed one of Van’s oil cooler shutters instead. It looks like it will work fine, when it flies.  

   

Terry  

RV-8A  

Seattle  

   

       

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Reak, Brad

 Sent: Thursday, May 29, 2008 7:56 AM

 To: rv-list(at)matronics.com

 Subject: Re: Fab Bypass Filter  

  

  

   

When I built my air box (RV7A) I followed the directions and built the alternate air door with the magnet.  After flying the first 20 hours and reading that Van’s had redesigned the alternate air door, I decided that for my type of flying, the benefit of an alternate air door was non-existent but the cost of having the door open when it should closed could be high ($$$).  So I sealed the door shut and am not loosing any sleep over the decision.  

   

Brad Reak – RV7A, 70 hours.   	  Quote: 	
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       [quote][b]

mr.sun

Joined: 30 Jan 2007
Posts: 85

Posted: Thu May 29, 2008 8:21 am Post subject: Fab Bypass Filter

I've got a -7 with the forward facing injection and no bypass installed.  I've been considering installing one.  My thought had been to put in a cable operated air door with some scat tubing feeding it from a NACA vent under the front of the cowl.  My thought was that it wouldn't clog or ice up when the air filter does even though it would be cold air.  The other use for it would be to increase my MP when I open it during cruise.

 

Any thoughts on this one?



Greg



do not archive



On Wed, May 28, 2008 at 7:08 PM, Emrath <emrath(at)comcast.net (emrath(at)comcast.net)> wrote:

[quote] --> RV-List message posted by: "Emrath" <emrath(at)comcast.net (emrath(at)comcast.net)>

 

 Starting around late 2003, or so I think, Van's put out a modification for

 bypassing the filter in the FAB should the filter get clogged. This is for

 the vertical induction carb or FI-servo installations.  The original method

 utilized a magnet and then a revised version utilized a cable operated by

 the pilot.  At the time, when I first fabricated the FAB, I modified it

 according to the original method using the magnet.  Today, as I finish up my

 panel and get prepared to put the forward top skin on, I began thinking

 about this once more.   So, I'm wondering if anyone still has the magnet

 version of this modification on their ship and can tell me if the bypass

 magnet releases and lets air bypass the filter under NORMAL operating

 conditions or not.  I'm driving myself crazy trying to determine what the

 NORMAL psi differential might be on this door to compare the calculated

 force needed to open the door and the amount the door will see during NORMAL

 operations.   Anyone/everyone have some thoughts on this?

 

 Marty in Brentwood, RV6A

 

 

 

 

 

 

 

 [b]

_________________
Greg RV-7

Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Thu May 29, 2008 10:06 am Post subject: Fab Bypass Filter

Greg,

 Connecting the bypass door via SCAT tubing hooked  up to a NACA vent would give you fresh, unheated, unfiltered air but  why open the bypass door in normal cruise? Van's ram air scoop supposedly  gives a minimal amount of MAP increase. Don't think the NACA vent would give any  ram air pressure. And would the NACA vent also be prone to freezing up to some  degree in a cold rain just as the filter in the airbox? Maybe not but worh  thinking about.

 Dale

 [quote]   ---

_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC

mr.sun

Joined: 30 Jan 2007
Posts: 85

Posted: Thu May 29, 2008 5:20 pm Post subject: Fab Bypass Filter

My thought is that the air filter robs some pressure and by providing fresh air from a scoop or NACA vent might make up for some of this loss.  I've thought about the vent being prone to freezing or ice but since it is on the bottom of the cowl and "facing" downward it would accumulate ice slower than the air filter which sits just inside the engine air inlet facing upwards just waiting for ice to cover it up.  This whole idea wouldn't be the best for preventing ice from suffocating the engine compared to warm air from inside the cowl but I think there might be some benefit from the ram air.  Maybe I need a larger NACA vent & tubing.  I don't want Van's lower snout, though.  Just don't like the looks of it.

 

Greg



On Thu, May 29, 2008 at 11:03 AM, Dale Ensing <densing(at)carolina.rr.com (densing(at)carolina.rr.com)> wrote:

[quote]        Greg,

 Connecting the bypass door via SCAT tubing hooked  up to a NACA vent would give you fresh, unheated, unfiltered air but  why open the bypass door in normal cruise? Van's ram air scoop supposedly  gives a minimal amount of MAP increase. Don't think the NACA vent would give any  ram air pressure. And would the NACA vent also be prone to freezing up to some  degree in a cold rain just as the filter in the airbox? Maybe not but worh  thinking about.

 Dale

 [quote]   ---

_________________
Greg RV-7

timrvator(at)comcast.net
Guest

Posted: Thu May 29, 2008 6:21 pm Post subject: Fab Bypass Filter

There's been one RV-6 fatal accident (that I personally know of) traced 

to a snow-clogged air filter.  Pilot and passenger killed. 

I was lucky to survive the same thing in my RV-6A several years ago.  

Van's bypass came out shortly thereafter.



Observations: 

- Snow at night or while IMC may not be visible or recognized. 

- The air filter can be blocked even when there is absolutely no visible 

moisture accumulation on the airframe exterior.

- "I'll remember to use carb heat as a preventative" can be 

overlooked/forgotten. 

- Once blockage has occurred, the carb heat in an RV (using the carb 

heat muff) will not melt the snow sufficient to restore required air 

flow into the engine.



Omit a filter bypass at your peril.



Tim



P.S.



Other observations:

- There exists a breed of FAA "investigator" who will manufacture 

fantastic stories if the facts don't support his pet views.

- A closed mouth and the AOPA legal services plan can be effective tools 

against this sort of FAA fiction writer.



-- 

Tim Lewis -- HEF (Manassas, VA)

RV-6A N47TD -- 1000 hrs

RV-10 #40059 under construction





[quote]



 The by-pass door, with magnet, on my O-360 was opening frequently. I 

 suspect on high MAP settings. It has been fixed closed. I have the 

 cable control for the door but have chosen not to put in on. I think 

 this was another CYA issue brought on after Van's became an employee 

 owned business.



 ---

emrath(at)comcast.net
Guest

Posted: Thu May 29, 2008 6:42 pm Post subject: Fab Bypass Filter

Well, seems the consensus is to just not use a bypass for the filter based

on the responses.  Thanks to everyone.



Marty in Brentwood, RV6A 



     Starting around late 2003, or so I think, Van's put out a modification

for

      bypassing the filter in the FAB should the filter get clogged. This is

for

      the vertical induction carb or FI-servo installations.  The original

method

      utilized a magnet and then a revised version utilized a cable operated

by

      the pilot.  At the time, when I first fabricated the FAB, I modified

it

      according to the original method using the magnet.  Today, as I finish

up my

      panel and get prepared to put the forward top skin on, I began

thinking

      about this once more.   So, I'm wondering if anyone still has the

magnet

      version of this modification on their ship and can tell me if the

bypass

      magnet releases and lets air bypass the filter under NORMAL operating

      conditions or not.  I'm driving myself crazy trying to determine what

the

      NORMAL psi differential might be on this door to compare the

calculated

      force needed to open the door and the amount the door will see during

NORMAL

      operations.   Anyone/everyone have some thoughts on this?

      

      Marty in Brentwood, RV6A

ronlee(at)pcisys.net
Guest

Posted: Thu May 29, 2008 7:03 pm Post subject: Fab Bypass Filter

Don't fly in snow/cold clouds.



Ron Lee



---

pitts_pilot(at)bellsouth.
Guest

Posted: Fri May 30, 2008 4:40 am Post subject: Fab Bypass Filter

Not exactly RV-related, but my Pitts has an alternate air flapper as 

standard equipment.  Much like the heat flapper on the firewall.  

Remember that besides snow/ice, the filters have been blocked by swarms 

of bugs, and toilet paper ('ribbon cutting' for the masses that like to 

play) and even balloons (again playing with our airplanes) .......and 

because I like to play ...... well, I'll have and alternate air source 

for my engine.  I don't mind an extra cable or fab time if it'll save my 

butt because I participated in some activity at a flyin.

YMMV.

Linn



Tim Lewis wrote:

 	  Quote: 	
		   



 There's been one RV-6 fatal accident (that I personally know of) 

 traced to a snow-clogged air filter.  Pilot and passenger killed. I 

 was lucky to survive the same thing in my RV-6A several years ago.  

 Van's bypass came out shortly thereafter.



 Observations: - Snow at night or while IMC may not be visible or 

 recognized. - The air filter can be blocked even when there is 

 absolutely no visible moisture accumulation on the airframe exterior.

 - "I'll remember to use carb heat as a preventative" can be 

 overlooked/forgotten. - Once blockage has occurred, the carb heat in 

 an RV (using the carb heat muff) will not melt the snow sufficient to 

 restore required air flow into the engine.



 Omit a filter bypass at your peril.



 Tim



 P.S.



 Other observations:

 - There exists a breed of FAA "investigator" who will manufacture 

 fantastic stories if the facts don't support his pet views.

 - A closed mouth and the AOPA legal services plan can be effective 

 tools against this sort of FAA fiction writer.

mr.sun

Joined: 30 Jan 2007
Posts: 85

Posted: Sun Jun 01, 2008 7:15 am Post subject: Fab Bypass Filter

So it sounds like the consensus is a bypass air flapper is a good idea for things in addition to ice.  However, does opening one while in cruise help with MP and power?  How about if it is getting cold air from below the prop somewhere?  Greg

 

do not archive



On Fri, May 30, 2008 at 5:36 AM, linn Walters <pitts_pilot(at)bellsouth.net (pitts_pilot(at)bellsouth.net)> wrote:

[quote] --> RV-List message posted by: linn Walters <pitts_pilot(at)bellsouth.net (pitts_pilot(at)bellsouth.net)>

 

 Not exactly RV-related, but my Pitts has an alternate air flapper as standard equipment.  Much like the heat flapper on the firewall.  Remember that besides snow/ice, the filters have been blocked by swarms of bugs, and toilet paper ('ribbon cutting' for the masses that like to play) and even balloons (again playing with our airplanes) .......and because I like to play ...... well, I'll have and alternate air source for my engine.  I don't mind an extra cable or fab time if it'll save my butt because I participated in some activity at a flyin.

  YMMV.

 Linn

 

 Tim Lewis wrote:

  	  Quote: 	
		   --> RV-List message posted by: Tim Lewis <timrvator(at)comcast.net (timrvator(at)comcast.net)>

 

 There's been one RV-6 fatal accident (that I personally know of) traced to a snow-clogged air filter.  Pilot and passenger killed. I was lucky to survive the same thing in my RV-6A several years ago.  Van's bypass came out shortly thereafter.

  

 Observations: - Snow at night or while IMC may not be visible or recognized. - The air filter can be blocked even when there is absolutely no visible moisture accumulation on the airframe exterior.

 - "I'll remember to use carb heat as a preventative" can be overlooked/forgotten. - Once blockage has occurred, the carb heat in an RV (using the carb heat muff) will not melt the snow sufficient to restore required air flow into the engine.

  

 Omit a filter bypass at your peril.

 

 Tim

 

 P.S.

 

 Other observations:

 - There exists a breed of FAA "investigator" who will manufacture fantastic stories if the facts don't support his pet views.

 - A closed mouth and the AOPA legal services plan can be effective tools against this sort of FAA fiction writer.

 

 	
 

 

 

 

 

 



[b]

_________________
Greg RV-7

carl.froehlich(at)cox.net
Guest

Posted: Sun Jun 01, 2008 9:50 am Post subject: Fab Bypass Filter

I believe the Van’s FAB/cowl arrangement provides a slight increase in MP.  Running with the filter bypass open would both drop MP and increase air temp to the engine – both are negative attributes for engine power.  

   

If you are suggesting adding another ram air intake for operations when bypassing the filter, some thoughts:  

<![if !supportLists]>-          <![endif]>You would not be able to measure the increase in MP if there is any.  The large air filter used by Van’s is very efficient.  

<![if !supportLists]>-          <![endif]>The extra intake would be hard to configure without the cowl looking ugly (at best) or adding unnecessary drag (at worst).  

<![if !supportLists]>-          <![endif]>You will end up with the same ice/bird blockage problem that the bypass was intended to prevent, except in this case your normal intake may have experienced the same blockage, thus you end up with no engine.  

   

Carl Froehlich  

RV-8A (425 hrs)  

RV-10 (flaps)  

     

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of mr.gsun(at)gmail.com

 Sent: Sunday, June 01, 2008 11:11 AM

 To: rv-list(at)matronics.com

 Subject: Re: Fab Bypass Filter  

  

   

So it sounds like the consensus is a bypass air flapper is a good idea for things in addition to ice.  However, does opening one while in cruise help with MP and power?  How about if it is getting cold air from below the prop somewhere?  Greg

 

 do not archive    

On Fri, May 30, 2008 at 5:36 AM, linn Walters <pitts_pilot(at)bellsouth.net (pitts_pilot(at)bellsouth.net)> wrote:  

--> RV-List message posted by: linn Walters <pitts_pilot(at)bellsouth.net (pitts_pilot(at)bellsouth.net)>

 

 Not exactly RV-related, but my Pitts has an alternate air flapper as standard equipment.  Much like the heat flapper on the firewall.  Remember that besides snow/ice, the filters have been blocked by swarms of bugs, and toilet paper ('ribbon cutting' for the masses that like to play) and even balloons (again playing with our airplanes) .......and because I like to play ..... well, I'll have and alternate air source for my engine.  I don't mind an extra cable or fab time if it'll save my butt because I participated in some activity at a flyin.

 YMMV.

 Linn    



 

 Tim Lewis wrote:  

--> RV-List message posted by: Tim Lewis <timrvator(at)comcast.net (timrvator(at)comcast.net)>

 

 There's been one RV-6 fatal accident (that I personally know of) traced to a snow-clogged air filter.  Pilot and passenger killed. I was lucky to survive the same thing in my RV-6A several years ago.  Van's bypass came out shortly thereafter.

 

 Observations: - Snow at night or while IMC may not be visible or recognized. - The air filter can be blocked even when there is absolutely no visible moisture accumulation on the airframe exterior.

 - "I'll remember to use carb heat as a preventative" can be overlooked/forgotten. - Once blockage has occurred, the carb heat in an RV (using the carb heat muff) will not melt the snow sufficient to restore required air flow into the engine.

 

 Omit a filter bypass at your peril.

 

 Tim

 

 P.S.

 

 Other observations:

 - There exists a breed of FAA "investigator" who will manufacture fantastic stories if the facts don't support his pet views.

 - A closed mouth and the AOPA legal services plan can be effective tools against this sort of FAA fiction writer.  

   

      



 

   

  

  

  

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        [quote][b]

mr.sun

Joined: 30 Jan 2007
Posts: 85

Posted: Sun Jun 01, 2008 4:43 pm Post subject: Fab Bypass Filter

Carl,  I now have the horizontal induction with fuel injection and the filter is in the right engine intake.  I love the looks and wouldn't want to add the "snout" underneath.  I'm not sure how much loss, if any, I get by not having the ram air intake underneath.  The K&N filter is approx 6" x 6" and it is just inside the cowl opening.  I question how much ram air pressure I get in that spot.  Greg

 

On Sun, Jun 1, 2008 at 10:46 AM, Carl Froehlich <carl.froehlich(at)cox.net (carl.froehlich(at)cox.net)> wrote:

[quote]              

I believe the Van's FAB/cowl arrangement provides a slight increase in MP.  Running with the filter bypass open would both drop MP and increase air temp to the engine – both are negative attributes for engine power.  

   

If you are suggesting adding another ram air intake for operations when bypassing the filter, some thoughts:  

-          You would not be able to measure the increase in MP if there is any.  The large air filter used by Van's is very efficient.  

-          The extra intake would be hard to configure without the cowl looking ugly (at best) or adding unnecessary drag (at worst).  

-          You will end up with the same ice/bird blockage problem that the bypass was intended to prevent, except in this case your normal intake may have experienced the same blockage, thus you end up with no engine.  

   

Carl Froehlich  

RV-8A (425 hrs)  

RV-10 (flaps)  

     

From: owner-rv-list-server(at)matronics.com (owner-rv-list-server(at)matronics.com) [mailto:owner-rv-list-server(at)matronics.com (owner-rv-list-server(at)matronics.com)] On Behalf Of mr.gsun(at)gmail.com (mr.gsun(at)gmail.com)

 Sent: Sunday, June 01, 2008 11:11 AM

 To: rv-list(at)matronics.com (rv-list(at)matronics.com)

 

Subject: Re: Fab Bypass Filter

  

  

   

So it sounds like the consensus is a bypass air flapper is a good idea for things in addition to ice.  However, does opening one while in cruise help with MP and power?  How about if it is getting cold air from below the prop somewhere?  Greg

 

 do not archive    

On Fri, May 30, 2008 at 5:36 AM, linn Walters <pitts_pilot(at)bellsouth.net (pitts_pilot(at)bellsouth.net)> wrote:  

--> RV-List message posted by: linn Walters <pitts_pilot(at)bellsouth.net (pitts_pilot(at)bellsouth.net)>

 

 Not exactly RV-related, but my Pitts has an alternate air flapper as standard equipment.  Much like the heat flapper on the firewall.  Remember that besides snow/ice, the filters have been blocked by swarms of bugs, and toilet paper ('ribbon cutting' for the masses that like to play) and even balloons (again playing with our airplanes) .......and because I like to play ..... well, I'll have and alternate air source for my engine.  I don't mind an extra cable or fab time if it'll save my butt because I participated in some activity at a flyin.

 YMMV.

 Linn    



 

 Tim Lewis wrote:  

--> RV-List message posted by: Tim Lewis <timrvator(at)comcast.net (timrvator(at)comcast.net)>

 

 There's been one RV-6 fatal accident (that I personally know of) traced to a snow-clogged air filter.  Pilot and passenger killed. I was lucky to survive the same thing in my RV-6A several years ago.  Van's bypass came out shortly thereafter.

 

 Observations: - Snow at night or while IMC may not be visible or recognized. - The air filter can be blocked even when there is absolutely no visible moisture accumulation on the airframe exterior.

 - "I'll remember to use carb heat as a preventative" can be overlooked/forgotten. - Once blockage has occurred, the carb heat in an RV (using the carb heat muff) will not melt the snow sufficient to restore required air flow into the engine.

 

 Omit a filter bypass at your peril.

 

 Tim

 

 P.S.

 

 Other observations:

 - There exists a breed of FAA "investigator" who will manufacture fantastic stories if the facts don't support his pet views.

 - A closed mouth and the AOPA legal services plan can be effective tools against this sort of FAA fiction writer.  

   

      



 

   

  

  

  

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		    http://www.matronics.com/Navigator?RV-List 	
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_________________
Greg RV-7

Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Mon Jun 02, 2008 5:16 am Post subject: Fab Bypass Filter

Very interesting Fred. Could you give us a little  more info to get a mental picture of the bypass around the filter? Did you  create an additional air passage on the fiberglass airbox?

 Dale

 do not achieve

 [quote]          Instead, I implemented my trap door to source it's air supply from the    airbox  (yes, there is plenty of space between the filter and the lower    level of the airbox..). This method allowed for the continued use of carb heat    if/when the filter was blocked, preventing the secondary carb ice failure    mode, and possibly melting the ice/snow that was blocking the    filter.

    

   Fred    Stucklen 

RV-6A   N926RV  (Sale    Pending)

   RV-7A  N924RV  (ready for an    engine)



[b]

_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC

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