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pitts_pilot(at)bellsouth.
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 Posted: Fri Feb 02, 2007 10:34 am Post subject: I've sworn off purge valve installations |
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Guys, the weather is sucky in FL, so I've been on the list a lot. You'll get rid of me when the weather clears!!! 
Read on!
kahuna wrote:
| Quote: | | Quote: | --> RV-List message posted by: "kahuna" <mike.stewart(at)us.ibm.com> (mike.stewart(at)us.ibm.com)
Well here I am again with this topic because I have some new data for you. Last month an RV-4 N360WS, based at my airport, had an engine failure while enroute and landed in a field. Pilot had his 10 yr old son with him. Both are ok. Plane is totaled. FAA has just completed its findings. PURGE VALVE FAILURE. Yep thats right. The pilot/builder did the same thing I did. Mounted and plumbed it without knowing that the little screws had to be safety wired. I was fortunate. HE was not. While he survived his off field, his show quality RV-4 is now in the heap pile. |
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Good and bad news.
| Quote: | | Quote: | | He also did not use his valve except for shut down. So I ask you... What are the chances that this is some isolated problem. 2 guys, from the same field, within a month of each other, with a failure of the purge valve? You still think its edge case? |
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I think you sabotaged his plane. No, not really, but I got your attention!!!
| Quote: | | Quote: |
I say to you again, I have sworn them off my planes. Not needed on an RV, adds both complexity and failure modes.
And if you have not checked your purge valve for the screws being safety wired, I suggest you get right on it. Sorry to bring this up again, but I feel at least compelled to bring you the data. |
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A reminder like this is terribly invaluable. Unfortunately it came too late for your friend. This is something that you might post periodically ..... it may save someone else's butt. I'd rather read it a hundred times than lose another plane and/or pilot.
Linn
do not archive
[quote] | Quote: |
See ya,
Mike
[quote="mstewart(at)iss.net"]After my second failure in a couple thousand hours of running fuel injection with pruge valves, I have concluded they are unnecessary and can have multiple failure modes that can bring you down.
As many of you know Airflow Performance of Spartanburg SC sells a terrific fuel injection system for all kinds of engines. from boats, to dragsters, to planes. I have had their system on 2 RVā€™s and have had 2 failures in the purge system. The purpose in the purge valve is simple. On a hot start, pull the valve, turn your pump on, and allow the hot vapors out for a few seconds. Close the valve and start your normal hot start procedures.
On my RV-6 I had the purge vale return line running into the cockpit and into a tee on the fuel inlet near the tank selector switch. AFP recommends this returning back to the tank, but I felt this to be too complex an installation. One day, while scudding back from SnF, close to home base, with Michelle in the right seat, the engine coughed and would barely run. I managed to limp home. After weeks of troubleshooting, it turned out that I had a crack in a tube FWF on the purge return line. This crack was allowing air into the return line, and hence air into the fuel flow to the engine. After this incident I decided on my next plane, I would NOT put the purge return line into the fuel supply system. This failure could have put me and my wife in the trees.
On my 8, I ran the purge return into the left tank vent. Thought being, let the vapors and a little fuel run to the ground. Donā€™t let a line leak here spoil my fuel. So on a trip last week with several RVā€™s and wifes to NYC for a play and a movie, plane died on landing rollout in NJ. ARGH! We finished our weekend getaway with the wifeā€™s, but on Sunday I put wife on a Delta flight home and began troubleshooting. What I found was the plane was way lean in running and would barely idle below 1500. I removed the fuel inlet to the servo and there was plenty of fuel going in, but the engine was not getting it. I checked screens and a few other things and no joy. I decided it was the servo not metering the fuel properly. I finally decided I try taking off and climbing to altitude and see if mother nature would richen it with altitude. Sure enough, around 7kā€™ I would get egtā€™s at pea
k, and at 10kā€™ I could run a little ROP. BUT the fuel flow was +4gph more than normal. H!
ow could that be? I dunno, but it was running smooth and I flew her home to Atlanta.
Safe in my own hanger, I removed the servo and flow divider and sent it to AFP. Don returned it with no problem found. ARGH! Spent the weekend troubleshooting and found the problem. The Purge valve was leaking internally and some fuel was by passing and going to the return side. Actually a lot of fuel was going to the return. This was causing lean operation and high fuel flow. I have now sent this to AFP for repair. I also suspect that this valve has been sending fuel to the return all along in the past 300 hours. I have gotten from day 1, and unexplained +1.5gph with my boost pump on.
In a couple thousand hours of RV injected operation in multiple aircraft, I have not found I needed this purge valve function for hot starts. In fact all I really use it for is to shut down the engine. Hot starts are easily handled with proper technique. I have now sworn off this purge valve madness as it provides no value in an RV and multiple failure modes.
Thought some of you might find this information useful.
Best,
Mike Stewart
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=92355#92355
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gerf(at)gerf.com
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| Posted: Fri Feb 02, 2007 10:54 am Post subject: I've sworn off purge valve installations |
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Mike,
Do you know more about why the valve leaked internally ? Was it malfunctioning or did the screw back out because it wasn't safety wired ?
Gerry.
(IO-320, AFP injection with purge valve on an RV-9 - FLYING!!)
| Quote: | Safe in my own hanger, I removed the servo and flow divider and sent it to AFP. Don returned it with no problem found. ARGH! Spent the weekend troubleshooting and found the problem. The Purge valve was leaking internally and some fuel was by passing and going to the return side. Actually a lot of fuel was going to the return. This was causing lean operation and high fuel flow. I have now sent this to AFP for repair. I also suspect that this valve has been sending fuel to the return all along in the past 300 hours. I have gotten from day 1, and unexplained +1.5gph with my boost pump on.
>
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dan(at)rvproject.com
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| Posted: Fri Feb 02, 2007 10:59 am Post subject: I've sworn off purge valve installations |
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If you do get rid of it, make sure you switch your fuel tank selector to OFF
every time you leave the plane sitting.
do not archive
)_( Dan
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kahuna
Joined: 02 Feb 2007
Posts: 93
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| Posted: Fri Feb 02, 2007 12:00 pm Post subject: I've sworn off purge valve installations |
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The screws back out and allow the valve to back out from the case.
Mike
Do not archive
From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Gerry Filby
Sent: Friday, February 02, 2007 1:54 PM
To: rv-list(at)matronics.com
Subject: Re: Re: I've sworn off purge valve installations
Mike,
Do you know more about why the valve leaked internally ? Was it malfunctioning or did the screw back out because it wasn't safety wired ?
Gerry.
(IO-320, AFP injection with purge valve on an RV-9 - FLYING!!)
>Safe in my own hanger, I removed the servo and flow divider and sent it to AFP. Don returned it with no problem found. ARGH! Spent the weekend troubleshooting and found the problem. The Purge valve was leaking internally and some fuel was by passing and going to the return side. Actually a lot of fuel was going to the return. This was causing lean operation and high fuel flow. I have now sent this to AFP for repair. I also suspect that this valve has been sending fuel to the return all along in the past 300 hours. I have gotten from day 1, and unexplained +1.5gph with my boost pump on.
> | Quote: | | http://www.matronics.com/Navigator?RV-List |
01234
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Fri Feb 02, 2007 12:03 pm Post subject: I've sworn off purge valve installations |
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Could you explain Dan?
I've not seen any need to go to OFF on my fuel injected Mooney, and doubt
you needed to on your Mooney either. They have never had purge valves.
[quote]
If you do get rid of it, make sure you switch your fuel tank selector to
OFF
every time you leave the plane sitting.
do not archive
)_( Dan
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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gerf(at)gerf.com
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| Posted: Fri Feb 02, 2007 12:25 pm Post subject: I've sworn off purge valve installations |
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So ... at the risk of starting a war ... if I left the cotter pins out of my flap mounting bolts and a flap fell off, should I conclude that the flaps are too much trouble or should I chastise myself for forgetting to install the cotter pins ?
Sorry, but I question your conclusion that purge valves have no place on an RV.
g
[quote]--
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dan(at)rvproject.com
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| Posted: Fri Feb 02, 2007 12:42 pm Post subject: I've sworn off purge valve installations |
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Which screws are we talkin' about here, the two that hold the purge valve to the flow divider bracket, or the one that holds the "arm stop" into the valve body?
Want to make sure I understand this fully.
do not archive
)_( Dan
[quote] ---
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dan(at)rvproject.com
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| Posted: Fri Feb 02, 2007 1:20 pm Post subject: I've sworn off purge valve installations |
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You don't have AFP injection on your Mooney. I should have clarified...
If you have AFP injection (i.e. an FM-200 servo), then leaning the mixture
all the way to the "ICO" position doesn't actually stop fuel flow
completely -- by design. Fuel still flows even when the mixture is back to
ICO stop.
I'm sitting here with the AFP manual right in front of me. On page 21 of
Revision B it says:
"When "ICO" is against the plastic stop, the fuel flow is shut off to the
engine. There is approximately 1.0 to 3.0 PPH leakage in this position."
And then below that in big bold it says:
"NOTE: The manual mixture is not intended to be used as a fuel shut valve.
If the fuel supply is near or above the level of the injector nozzles fuel
will seep into the engine, or seep out the injector nozzle vents. A zero
leak fuel shut off valve must be used on these installations."
Granted, we aren't talking about high-wing setups here, but in principle we
need to consider this effect.
The purge valve is what is responsible for completely cutting off the flow
of fuel to the cylinders. If you remove the purge valve from an AFP system,
you have no way to completely stop the flow of fuel unless you literally cut
off fuel supply at the fuel selector valve.
Note also that on page 32 of Revision B, where it talks about installing the
purge valve, it clearly says:
"Lock wire all hardware. Make sure to lock wire the stop screw."
I hope this clarifies what I meant, and I'm sure Don Rivera at AFP will
correct me if I'm wrong.
)_( Dan
RV-7 N714D
www.rvproject.com
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kahuna
Joined: 02 Feb 2007
Posts: 93
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| Posted: Fri Feb 02, 2007 4:32 pm Post subject: Re: I've sworn off purge valve installations |
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[quote="gerf(at)gerf.com"]So ... at the risk of starting a war ... if I left the cotter pins out of my flap mounting bolts and a flap fell off, should I conclude that the flaps are too much trouble or should I chastise myself for forgetting to install the cotter pins ?
Sorry, but I question your conclusion that purge valves have no place on an RV.
g
The flaps serve a very useful purpose. One that can be demonstrated and quantified. I say the purge vavle can do neither of these. As for the servo not being at idle cut with fuel flow, that can be fixed.
Mike
do not archive
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Terry Watson
Joined: 09 Jan 2006
Posts: 290
Location: Seattle, WA USA
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| Posted: Fri Feb 02, 2007 6:15 pm Post subject: I've sworn off purge valve installations |
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I think that the point is that, according to Airflow Performance's manual,
when the servo is at idle cut-off there may still be enough fuel flow to
keep the engine from shutting down. Are you confident that you can stop the
engine without using the purge valve?
Terry
Maybe if we archived this we wouldn't have to go through it every six
months.
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Gary.A.Sobek
Joined: 09 Jan 2006
Posts: 217
Location: SoCAL USA
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| Posted: Fri Feb 02, 2007 7:48 pm Post subject: I've sworn off purge valve installations |
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I know of one RV accident that totaled the airplane where the fuel injected
engine quit after takeoff. Post crash investigation sure looked like VAPOR
LOCK to me. If that airplane had a purge valve and was used before
starting, there may be one additional RV flying today.
I agree that a FI system should not need a purge valve to SHUT OFF the
engine but one fuel injector manufacturer made his servo require one.
Gary A. Sobek
"My Sanity" RV-6 N157GS O-320 Hartzell,
1,977 + Flying Hours So. CA, USA
----Original Message Follows----
From: "kahuna" <mike.stewart(at)us.ibm.com>
Reply-To: rv-list(at)matronics.com
To: rv-list(at)matronics.com
Subject: Re: I've sworn off purge valve installations
Date: Fri, 2 Feb 2007 16:32:21 -0800
[quote="gerf(at)gerf.com"]So ... at the risk of starting a war ... if I left
the cotter pins out of my flap mounting bolts and a flap fell off, should I
conclude that the flaps are too much trouble or should I chastise myself for
forgetting to install the cotter pins ?
Sorry, but I question your conclusion that purge valves have no place on an
RV.
g
> --
The flaps serve a very useful purpose. One that can be demonstrated and
quantified. I say the purge vavle can do neither of these. As for the servo
not being at idle cut with fuel flow, that can be fixed.
Mike
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rocketbob(at)gmail.com
Guest
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| Posted: Fri Feb 02, 2007 7:59 pm Post subject: I've sworn off purge valve installations |
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On 2/2/07, Dan Checkoway <dan(at)rvproject.com (dan(at)rvproject.com)> wrote: | Quote: | --> RV-List message posted by: "Dan Checkoway" <dan(at)rvproject.com (dan(at)rvproject.com)>
If you have AFP injection (i.e. an FM-200 servo), then leaning the mixture
all the way to the "ICO" position doesn't actually stop fuel flow
completely -- by design. Fuel still flows even when the mixture is back to
ICO stop.
|
Why doesn't the AFP system allow ICO by pulling the mixture.? I have always wondered why this is the case. I have an RSA-10 servo, and it allows ICO.
Regards,
Bob Japundza
RV-6 flying F1 under const.
[quote][b]
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pitts_pilot(at)bellsouth.
Guest
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| Posted: Fri Feb 02, 2007 8:16 pm Post subject: I've sworn off purge valve installations |
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RV6 Flyer wrote:
| Quote: |
I know of one RV accident that totaled the airplane where the fuel
injected engine quit after takeoff. Post crash investigation sure
looked like VAPOR LOCK to me.
|
Hmmm. The engine started, ran long enough to taxi to the runway, some
full-power takeoff and short flight ..... explain to me how that could
be caused by vapor lock??? How did it look like vapor lock????
I would be more inclined to believe excessive water in the fuel (did the
plane sit outside in a lot of rain before flying, have leaking fuel caps
to allow the water in, and the pilot didn't sump the tanks??? Not
likely, but stupid pilot tricks do happen.) or carb ice or ..... almost
anything but vapor lock.
Linn
do not archive.
| Quote: | If that airplane had a purge valve and was used before starting,
there may be one additional RV flying today.
I agree that a FI system should not need a purge valve to SHUT OFF the
engine but one fuel injector manufacturer made his servo require one.
Gary A. Sobek
"My Sanity" RV-6 N157GS O-320 Hartzell,
1,977 + Flying Hours So. CA, USA
----Original Message Follows----
From: "kahuna" <mike.stewart(at)us.ibm.com>
Reply-To: rv-list(at)matronics.com
To: rv-list(at)matronics.com
Subject: Re: I've sworn off purge valve installations
Date: Fri, 2 Feb 2007 16:32:21 -0800
[quote="gerf(at)gerf.com"]So ... at the risk of starting a war ... if
I left the cotter pins out of my flap mounting bolts and a flap fell
off, should I conclude that the flaps are too much trouble or should I
chastise myself for forgetting to install the cotter pins ?
Sorry, but I question your conclusion that purge valves have no place
on an RV.
g
> --
The flaps serve a very useful purpose. One that can be demonstrated
and quantified. I say the purge vavle can do neither of these. As for
the servo not being at idle cut with fuel flow, that can be fixed.
Mike
_________________________________________________________________
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lifeofreiley2003(at)yahoo
Guest
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| Posted: Fri Feb 02, 2007 8:52 pm Post subject: I've sworn off purge valve installations |
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Linn,
I believe Gary stated the plane was 'fuel injected".
Darrell
do not archive
--- linn Walters <pitts_pilot(at)bellsouth.net> wrote:
| Quote: |
<pitts_pilot(at)bellsouth.net>
RV6 Flyer wrote:
>
<rv6_flyer(at)hotmail.com>
>
> I know of one RV accident that totaled the
airplane where the fuel
> injected engine quit after takeoff. Post crash
investigation sure
> looked like VAPOR LOCK to me.
Hmmm. The engine started, ran long enough to taxi
to the runway, some
full-power takeoff and short flight ..... explain to
me how that could
be caused by vapor lock??? How did it look like
vapor lock????
I would be more inclined to believe excessive water
in the fuel (did the
plane sit outside in a lot of rain before flying,
have leaking fuel caps
to allow the water in, and the pilot didn't sump the
tanks??? Not
likely, but stupid pilot tricks do happen.) or carb
ice or ..... almost
anything but vapor lock.
Linn
do not archive.
> If that airplane had a purge valve and was used
before starting,
> there may be one additional RV flying today.
>
> I agree that a FI system should not need a purge
valve to SHUT OFF the
> engine but one fuel injector manufacturer made his
servo require one.
>
>
> Gary A. Sobek
> "My Sanity" RV-6 N157GS O-320 Hartzell,
> 1,977 + Flying Hours So. CA, USA
>
>
>
>
> ----Original Message Follows----
> From: "kahuna" <mike.stewart(at)us.ibm.com>
> Reply-To: rv-list(at)matronics.com
> To: rv-list(at)matronics.com
> Subject: Re: I've sworn off purge valve
installations
> Date: Fri, 2 Feb 2007 16:32:21 -0800
>
>
<mike.stewart(at)us.ibm.com>
>
> [quote="gerf(at)gerf.com"]So ... at the risk of
starting a war ... if
> I left the cotter pins out of my flap mounting
bolts and a flap fell
> off, should I conclude that the flaps are too much
trouble or should I
> chastise myself for forgetting to install the
cotter pins ?
>
> Sorry, but I question your conclusion that purge
valves have no place
> on an RV.
>
> g
>
>
> > --
>
>
> The flaps serve a very useful purpose. One that
can be demonstrated
> and quantified. I say the purge vavle can do
neither of these. As for
> the servo not being at idle cut with fuel flow,
that can be fixed.
>
> Mike
>
>
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jhstarn(at)verizon.net
Guest
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| Posted: Fri Feb 02, 2007 9:09 pm Post subject: I've sworn off purge valve installations |
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A wee bit O humor.......
IF I left the cotter keys out & the flap fell off, I would much too
preoccupied to think about "should I chastise myself for forgetting to
install the cotter pins ?" Do Not Archive KABONG 8*)
So ... at the risk of starting a war ... if I left the cotter pins out of my
flap mounting bolts and a flap fell off, should I conclude that the flaps
are too much trouble or should I chastise myself for forgetting to install
the cotter pins ?
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kahuna
Joined: 02 Feb 2007
Posts: 93
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| Posted: Sat Feb 03, 2007 3:49 am Post subject: Re: I've sworn off purge valve installations |
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| Gary.A.Sobek wrote: | I know of one RV accident that totaled the airplane where the fuel injected
engine quit after takeoff. Post crash investigation sure looked like VAPOR
LOCK to me. If that airplane had a purge valve and was used before
starting, there may be one additional RV flying today.
I agree that a FI system should not need a purge valve to SHUT OFF the
engine but one fuel injector manufacturer made his servo require one.
Gary A. Sobek
"My Sanity" RV-6 N157GS O-320 Hartzell,
1,977 + Flying Hours So. CA, USA
|
Gary I do not see how this is a possible senerio argue purge to the AFP system. Here is why.
THere are many opportunities for vapor lock. The AFP purge vaule is mounted right before the spider. If used per the manual, you purge for a few seconds and start. Now if a guy has not used the purge valve, starts, taxis, and takes off, he has already run for minutes and done way more by running than the purge valve ever did. Running the purge valve, with boost on, will only dribble fuel since the meter device is not getting air flow. Im not sure what the flow is, Id guess ~ 1gph. So if you run the purge for 20 seconds you have moved some miniscule amount of fresh fuel into the lines. Which is fine since you dont need much movement in the injection lines to purge vapor. If you run your engine at take off power for even a few seconds you have blasted fresh fuel into the system at an order of magnatude greater than 1gph. In an IO360 for example. One second of take off power is worth ~20 seconds of purge, at least in terms of fuel flow of fresh fuel. And Ill bet the number is several times that. Im only guessing at the purge fuel flow. The only design senerio Im aware of for the purge is to help with vapor lock starts, not vapor lock while airborn. You will have to convince me that operating a purge valve on the ground would have prevented your accident senerio.
Also Im with the others, whats the point of ICO still delivering fuel? I have over 2k AFP hours in multiple planes, and I dont use the purge for anything.
Talk to me Gary
Mike
PS Smoozer is doing well and mentioned your help
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garrys(at)tampabay.rr.com
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| Posted: Sat Feb 03, 2007 4:55 am Post subject: I've sworn off purge valve installations |
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I've been reading this thread with some interest, hoping to learn something practical when I begin flying my RV 7A. I have an IO360 from Aerosport and hope to be flying in the next couple of months. What I don't understand is why can't you shut down the engine simply by turning off the mag switches? Why the need to shut down by starving the engine of fuel? We don't do this with our cars, or lawnmowers, or any other gasoline engine powered device, so why airplanes?
Garry Stout
Tampa Florida
[quote] ---
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phil(at)petrasoft.net
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| Posted: Sat Feb 03, 2007 7:00 am Post subject: I've sworn off purge valve installations |
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Cars, boats, and lawnmowers don't have a big fan sticking out in front
of them that can be used to turn the engine. Using the mag switches to
kill the engine will leave some properly mixed fuel in the cylinders and
then if you (or somebody) moves the prop and the impulse coupler
fires.... Not a good day.
There is also a school of thought that the gasoline in the cylinders of
a horizontally opposed engine will wash oil off the cylinder walls and
increase wear. I don't know if I buy this one but I've seen enough
people turning props on the ramp (for reasons that I don't understand)
to be fearful of having fuel in the cylinders.
Godspeed,
Phil Birkelbach - Houston Texas
RV-7 N727WB
http://www.myrv7.com
Garry wrote:
[quote] I've been reading this thread with some interest, hoping to learn
something practical when I begin flying my RV 7A. I have an IO360
from Aerosport and hope to be flying in the next couple of months.
What I don't understand is why can't you shut down the engine simply
by turning off the mag switches? Why the need to shut down by
starving the engine of fuel? We don't do this with our cars, or
lawnmowers, or any other gasoline engine powered device, so why airplanes?
Garry Stout
Tampa Florida
---
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pitts_pilot(at)bellsouth.
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| Posted: Sat Feb 03, 2007 7:34 am Post subject: I've sworn off purge valve installations |
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And your point is???? I have a problem when, in the absence of any clear data, a malfunction is attributed to 'vapor lock'. I've put up with all the rhetoric for a lot of years running auto fuel ..... in FL, on hot days, with both injected and carb'd engines (yep, run auto fuel through the injected engine too ..... but not near as much as through a carb) with nary a hiccup. Not even any more hard starting problems than using 100LL. I guess the statement 'looked like vapor lock to me' just rubbed me the wrong way. Sorry. I really would rather have statements backed up by data or first-person-experience, not (to seal a line from a song) 'I heard it from a friend, who, heard it from a friend, who .... '.
The point I tried to make (and failed, I guess) is that all that engine running after startup should have purged any heat-soaked fuel. Once the heat soaked fuel is gone (from the firewall forward), the possibility of vapor lock goes way down ......
Linn ...... calmed down without the drugs 
do not archive
Darrell Reiley wrote:
[quote] | Quote: | --> RV-List message posted by: Darrell Reiley <lifeofreiley2003(at)yahoo.com> (lifeofreiley2003(at)yahoo.com)
Linn,
I believe Gary stated the plane was 'fuel injected".
Darrell
do not archive
--- 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)
RV6 Flyer wrote:
| Quote: | --> RV-List message posted by: "RV6 Flyer"
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<rv6_flyer(at)hotmail.com> (rv6_flyer(at)hotmail.com)
| Quote: | I know of one RV accident that totaled the
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airplane where the fuel
| Quote: | injected engine quit after takeoff. Post crash
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investigation sure
| Quote: | looked like VAPOR LOCK to me.
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Hmmm. The engine started, ran long enough to taxi
to the runway, some
full-power takeoff and short flight ..... explain to
me how that could
be caused by vapor lock??? How did it look like
vapor lock????
I would be more inclined to believe excessive water
in the fuel (did the
plane sit outside in a lot of rain before flying,
have leaking fuel caps
to allow the water in, and the pilot didn't sump the
tanks??? Not
likely, but stupid pilot tricks do happen.) or carb
ice or ..... almost
anything but vapor lock.
Linn
do not archive.
0 --> RV-List message posted by: linn Walters
<pitts_pilot(at)bellsouth.net> (pitts_pilot(at)bellsouth.net)
RV6 Flyer wrote:
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9 3 5 7 <rv6_flyer(at)hotmail.com> (rv6_flyer(at)hotmail.com)
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9 | Quote: | | Quote: | | Quote: | I know of one RV accident that totaled the
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4 [b]
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pitts_pilot(at)bellsouth.
Guest
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| Posted: Sat Feb 03, 2007 7:45 am Post subject: I've sworn off purge valve installations |
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As it was explained to me ...... shutting down with the mags allowed unburned fuel to be passed through the cylinders and would wash some of the oil off the cylinder walls ....... inviting the opportunity for the cylinder walls to rust. The difference in the auto analogy is that we seldom allow our cars to sit idle for months at a time. I realize that most of us experimental drivers don't let our airplanes sit for very long ...... but the practice was for the masses ...... who own those ramp/hangar queens on your airport!!!
Linn ...... weather is better ..... but still sucky.
do not archive
Garry wrote:
[quote] I've been reading this thread with some interest, hoping to learn something practical when I begin flying my RV 7A. I have an IO360 from Aerosport and hope to be flying in the next couple of months. What I don't understand is why can't you shut down the engine simply by turning off the mag switches? Why the need to shut down by starving the engine of fuel? We don't do this with our cars, or lawnmowers, or any other gasoline engine powered device, so why airplanes?
Garry Stout
Tampa Florida
| Quote: | ----- Original Message -----
From: Bob J. (rocketbob(at)gmail.com)
To: rv-list(at)matronics.com (rv-list(at)matronics.com)
Sent: Friday, February 02, 2007 10:59 PM
Subject: Re: Re: I've sworn off purge valve installations
On 2/2/07, Dan Checkoway <dan(at)rvproject.com (dan(at)rvproject.com)> wrote: | Quote: | --> RV-List message posted by: "Dan Checkoway" <dan(at)rvproject.com (dan(at)rvproject.com)>
If you have AFP injection (i.e. an FM-200 servo), then leaning the mixture
all the way to the "ICO" position doesn't actually stop fuel flow
completely -- by design. Fuel still flows even when the mixture is back to
ICO stop.
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Why doesn't the AFP system allow ICO by pulling the mixture.? I have always wondered why this is the case. I have an RSA-10 servo, and it allows ICO.
Regards,
Bob Japundza
RV-6 flying F1 under const.
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[b]
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