Today's Message Index:
----------------------
1. 01:24 AM - Re: stopping engine (Charlie England)
2. 01:24 AM - Re: stopping engine (Bill Bradburry)
3. 05:23 AM - Re: stopping engine (Bill Bradburry)
4. 06:08 AM - Re: stopping engine (Ed Anderson)
5. 08:34 AM - IVO Prop Current Limiter/Electronic Circuit Breaker (Robert L. Nuckolls, III)
6. 01:15 PM - Re: stopping engine (Matt Prather)
7. 04:13 PM - Re: stopping engine (n801bh@netzero.com)
8. 07:38 PM - Check out THIS structural test event (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: stopping engine |
A couple of thoughts.
With electronic automotive injection, killing the injector power will
stop the injectors, but the fuel rail will still be pressurized. If an
injector is a bit leaky, fuel can still make it to the combustion
chamber after shutdown. Some guys provide a tiny bleed hole that
bypasses the regulator so the fuel rail will depressurize a minute or so
after shutdown (probably overkill, but there it is).
On the subject of traditional a/c engines with carbs, there is a
possible misconception buried below (I hate RPN posting....). I read
about the following somewhere & was surprised, but cutaway drawings of
some a/c carbs seem to support the story. I believe that the McNeilly
(sp?) leaning block for Holley carbs works this way, too, and the
technique has been used to lean some motorcycle carbs on alternative
engines. Here's the 'story':
On at least some a/c carbs, the mixture control is actually controlling
the vent to the fuel bowl on the carb. Pulling mixture to idle cutoff on
those carbs just causes the 'head' (air pressure+fuel weight) on the
fuel in the bowl to drop until it equals the absolute pressure in the
venturi, stopping flow. Once the engine stops, pressure can equalize at
ambient. If the prop spins after that happens, and the mags are on, the
engine can fire because there's still fuel available & there's now a
(short term) normal 'head' of ambient pressure on the fuel in the bowl.
Charlie
On 4/28/2010 11:32 AM, Mike Fontenot wrote:
> I have a GEO engine, EFI is the EC2 system, with 2 fuel pumps going
> into a single line, then to the fuel rail. In that line is a 3 way
> valve that I can use to bypass the rail and spill back into the fuel
> tank. Turning off the engine by starving the fuel, yet keeping the
> pumps running smoothly works quite well.
>
> On Wed, Apr 28, 2010 at 10:11 AM, Kenneth Johnson
> <kjohnsondds@yahoo.com <mailto:kjohnsondds@yahoo.com>> wrote:
>
> Hi All,
> I would like to thank all who responded.
> It would seem the best reason to stop an engine with fuel
> starvation would be to prevent possible danger from the prop. If
> a prop was repositioned, fuel in a cylinder might ignite, which in
> turn would turn the prop and that might hurt someone. In an
> automobile, if dieseling occurs, no is hurt. The car is in "Park"
> or "Neutral."
> I have a Mazda rotary engine I will be using for my airplane.
> Eventhough this is not a piston engine, the threat of danger from
> the prop with fuel left in the burn chamber still exists. For
> safety reasons, fuel starvation would be the best way to stop the
> engine. Turning off the ignition will stop current to the spark
> plugs, coils, and will turn off the high pressure fuel pump.
> However, it would seem that turning off the fuel pump before
> turning off the ignition would be a safer way to eliminate fuel
> from the burn chambers.
> By using a valve on my fuel rail, I could stop fuel. However, the
> fuel pump would still be working and could be damaged. Again, it
> would seem that switching off the fuel pump before the
> ignition might be the best solution.
> If anyone has a better solution, please post.
> Thanks,
> Ken Johnson
>
> ------------------------------------------------------------------------
> *From:* Matt Prather <mprather@spro.net <mailto:mprather@spro.net>>
> *To:* aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> *Sent:* Tue, April 27, 2010 1:54:43 PM
> *Subject:* RE: AeroElectric-List: stopping engine
>
> <mprather@spro.net <mailto:mprather@spro.net>>
>
> I think it's worthwhile to be precise (reduce ambiguity) in
> matters such
> as this.
>
> I believe many (most?) light airplane POH's specify that engine
> shutdown
> is accomplished by moving the mixture control to idle-cutoff (ICO).
> Usually this causes the engine to stop running fairly rapidly - in a
> matter of a couple of seconds. Selecting rich mixture and hitting the
> starter usually allows the engine to restart very quickly/easily.
>
> Certainly many airplanes still have Stromberg carbs (or similar) which
> don't have a mixture control effective enough to cause
> "idle-cutoff". I
> have ridden with pilots of such airplanes who only use the magneto
> switches to stop the engine. One benefit of this procedure is
> that you
> check to see if you have a "hot mag" on each flight. If the
> engine stops
> dead, you can be somewhat certain that the p-lead circuit is in
> working
> condition.
>
> Most (all?) light airplanes also have at least one fuel control valve
> (selector), which can also be used to stop the flow of fuel to the
> engine.
> On the carbureted engines that I have operated, closing this fuel
> valve
> does eventually stop the engine, though depending on how low the
> throttle
> setting is, it might take a few minutes for the float bowl in the
> carb to
> get low enough to cause the engine to lean-out and die. Usually
> when I
> pull up to a parking spot, I don't feel like waiting for the carb to
> empty, so I never do this.
>
> If the fuel valve was turned off, on carbureted airplanes with gravity
> feed fuel, turning on the fuel valve and waiting a few moments
> will refill
> the carb float bowl, at which point the engine may be restarted.
> For an
> airplane with pump driven fuel, turning on the electric pump will
> allow
> restarting much faster/sooner than if only the engine driven pump
> is used.
> Turning on the electric pump is often in the engine start procedure.
>
> In an airplane that depends on a high pressure electric pump, I'm
> not sure
> it makes sense to "turn off the fuel," if that implies closing
> some kind
> of fuel valve. It might make more sense to turn off the electric
> pump(s).
>
> My impression of automotive fuel injection is that turning the key off
> stops power to both the ignition and the fuel pump(s). This leaves
> burnable mixture in the cylinders and intake manifold. In an
> airplane,
> this method of stopping the engine increases the risk of
> unexpected prop
> motion. Turning the key to run causes the fuel pump(s) to run
> until the
> specified system pressure is reached, at which point the pump(s)
> turn off.
>
> One other thing I have noticed is that some electronic ignition
> systems
> may fire the spark plugs one time when the system is energized.
> This will
> likely cause the prop to turn if there is a burnable mixture in the
> cylinders. In fact, my Varieze has such a system. A number of
> times I
> have actually had the engine start spontaneously because of this
> effect -
> prime with accelerator pump, walk the prop to pull fuel into the
> cylinders, turn on the ignition, and away it goes. So, magnetos
> aren't
> the only things that will fire unexpectedly. In fact, a mag
> without an
> impulse couple isn't likely going to spark on its own..
>
> So to get back to the original question, I agree that stopping
> the fuel
> delivery in some way is generally a good idea. I think turning
> off the
> pumps while leaving the ignition firing is the best bet, as that
> should
> dump fuel system pressure, and yield the least burnable mixture in the
> cylinders.
>
> With all that said, everyone working around aircraft should be very
> careful of the propeller, whatever method is used to stop the engine.
> Pilots need to be vigilant to not allow anyone to haphazardly move the
> prop or stand in the prop arc.
>
>
> Regards,
>
> Matt-
>
> > In an Aviation carbed or injected engine, the shutoff method is the
> > same- turn off the fuel. The reason for this is to prevent a
> fuel/air
> > mixture being left in a cylinder. If a P lead wire is broken and the
> > propeller is turned, it could fire and injure someone. From your
> > question I assume youre installing an auto engine.
> >
> > Auto engines kill the spark. Some might also kill the pressure
> in the
> > fuel rail. Youre going to have to blas your own trail here.
> >
> > Bruce
> > www.Glasair.org <http://www.glasair.org/>
> > -----Original Message-----
> > From: owner-aeroelectric-list-server@matronics.com
> <mailto:owner-aeroelectric-list-server@matronics.com>
> > [mailto:owner-aeroelectric-list-server@matronics.com
> <mailto:owner-aeroelectric-list-server@matronics.com>] On Behalf Of
> > Kenneth Johnson
> > Sent: Tuesday, April 27, 2010 12:45 PM
> > To: aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> > Subject: AeroElectric-List: stopping engine
> >
> > Aircraft Electrical Gurus,
> > This subject has been presented briefly recently, but I was
> looking for
> > the opinion of several. This may have an electrical solution of
> not.
> > The question is: "What is the best way to stop your aircraft engine?
> >
> > In the recent past, at this site I have seen recommended a
> switch to the
> > fuel pump. Turn off the fuel pump and eventually the engine stops.
> >
> > I rent Cessna 172 and the prefered way to stop the engine is to
> minimize
> > both the throttle and richness knobs by pulling them out.
> Technically,
> > what exactly does this do? Could I place a simple ball valve on
> my fuel
> > rail and phsically close it? Is this what I do on the Cessna
> 172? The
> > Cessna fuel is fed throught a carburetor and my engine is fuel
> injected.
> > Does that make a difference?
> >
> > On the automobile engine, when we turn off the engine, are we just
> > closing the switch that provides current to the spark plugs, or is
> > something else involved? Is this what should be done for the
> aircraft
> > engine?
> >
> > Thanks for your advice.
> >
> > Ken Johnson
> >
> >
> >
> >
>
>
> *
>
> ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
> tp://forums.matronics.com
> _blank">http://www.matronics.com/contribution
>
> *
>
>
> --
> Mike
>
> ===============================
> Mike Fontenot
> Apex Consulting & Services LLC
> Lakewood, Colorado
> 303 / 731-6645
> mikef AT apexconsultingservices DOT com
> ======
> *
>
>
> *
Message 2
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Matt,
One other consideration about the Mazda rotary vs a typical piston airplane
engine is the blade rotation involved. If either whacked you in the head,
you would probably not be real happy about it. However...
The 4 cycle piston engine will rotate the prop 180 degrees on one power
stroke, but the rotary will only rotate the crankshaft 120 degrees if all
three rotor faces fire and only 40 degrees if one face fires. Since the
rotary has a PSRU on it which is probably either 2.17 or 2.85 to 1, this
would further reduce the prop movement to 18.5 to 14 degrees depending on
which PSRU.
The rotary would give you a good whack, but you would have to be standing
close to the blade for it to hit you.
Bill B
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Matt
Prather
Sent: Wednesday, April 28, 2010 2:04 PM
Subject: RE: AeroElectric-List: stopping engine
Bill,
My only concern about this (and it's probably a remote concern) is that if
you have a leaking injector, it may dribble fuel into the engine after
shutdown. Otherwise, this is very much analogous to pulling the mixture
to ICO on an aircraft carb or mechanical injection.
Matt-
> Ken,
>
> You didnt say if you have fuel injection or a carb on your Mazda rotary,
> but if you have FI, you can shut off the injectors and the engine will
> immediately stop due to fuel starvation. No fuel will be left in the
> rotor
> faces. The fuel regulator will then immediately open up to keep the fuel
> pressure at your set point, so the fuel pumps will not be adversely
> affected. In fact, this is the condition you will have the regulator and
> pumps in when you set the fuel pressure. This is the way it is designed
> to
> work so no damage will ensue. After the engine stops you can leisurely
> shut
> everything else down. There will be no fuel in the rotors so there will
> be
> no danger if you want to move the prop for whatever reason.
>
> If you have a carb, well, you are on your own.. :>)
>
>
> Bill B
>
>
> _____
>
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kenneth
> Johnson
> Sent: Wednesday, April 28, 2010 12:11 PM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: stopping engine
>
>
> Hi All,
>
> I would like to thank all who responded.
>
>
> It would seem the best reason to stop an engine with fuel starvation would
> be to prevent possible danger from the prop. If a prop was repositioned,
> fuel in a cylinder might ignite, which in turn would turn the prop and
> that
> might hurt someone. In an automobile, if dieseling occurs, no is hurt.
> The
> car is in "Park" or "Neutral."
>
>
> I have a Mazda rotary engine I will be using for my airplane. Eventhough
> this is not a piston engine, the threat of danger from the prop with fuel
> left in the burn chamber still exists. For safety reasons, fuel
> starvation
> would be the best way to stop the engine. Turning off the ignition will
> stop current to the spark plugs, coils, and will turn off the high
> pressure
> fuel pump. However, it would seem that turning off the fuel pump before
> turning off the ignition would be a safer way to eliminate fuel from the
> burn chambers.
>
>
> By using a valve on my fuel rail, I could stop fuel. However, the fuel
> pump
> would still be working and could be damaged. Again, it would seem that
> switching off the fuel pump before the ignition might be the best
> solution.
>
>
> If anyone has a better solution, please post.
>
>
> Thanks,
>
>
> Ken Johnson
>
>
> _____
>
> From: Matt Prather <mprather@spro.net>
> To: aeroelectric-list@matronics.com
> Sent: Tue, April 27, 2010 1:54:43 PM
> Subject: RE: AeroElectric-List: stopping engine
>
> <mprather@spro.net>
>
> I think it's worthwhile to be precise (reduce ambiguity) in matters such
> as this.
>
> I believe many (most?) light airplane POH's specify that engine shutdown
> is accomplished by moving the mixture control to idle-cutoff (ICO).
> Usually this causes the engine to stop running fairly rapidly - in a
> matter of a couple of seconds. Selecting rich mixture and hitting the
> starter usually allows the engine to restart very quickly/easily.
>
> Certainly many airplanes still have Stromberg carbs (or similar) which
> don't have a mixture control effective enough to cause "idle-cutoff". I
> have ridden with pilots of such airplanes who only use the magneto
> switches to stop the engine. One benefit of this procedure is that you
> check to see if you have a "hot mag" on each flight. If the engine stops
> dead, you can be somewhat certain that the p-lead circuit is in working
> condition.
>
> Most (all?) light airplanes also have at least one fuel control valve
> (selector), which can also be used to stop the flow of fuel to the engine.
> On the carbureted engines that I have operated, closing this fuel valve
> does eventually stop the engine, though depending on how low the throttle
> setting is, it might take a few minutes for the float bowl in the carb to
> get low enough to cause the engine to lean-out and die. Usually when I
> pull up to a parking spot, I don't feel like waiting for the carb to
> empty, so I never do this.
>
> If the fuel valve was turned off, on carbureted airplanes with gravity
> feed fuel, turning on the fuel valve and waiting a few moments will refill
> the carb float bowl, at which point the engine may be restarted. For an
> airplane with pump driven fuel, turning on the electric pump will allow
> restarting much faster/sooner than if only the engine driven pump is used.
> Turning on the electric pump is often in the engine start procedure.
>
> In an airplane that depends on a high pressure electric pump, I'm not sure
> it makes sense to "turn off the fuel," if that implies closing some kind
> of fuel valve. It might make more sense to turn off the electric pump(s).
>
> My impression of automotive fuel injection is that turning the key off
> stops power to both the ignition and the fuel pump(s). This leaves
> burnable mixture in the cylinders and intake manifold. In an airplane,
> this method of stopping the engine increases the risk of unexpected prop
> motion. Turning the key to run causes the fuel pump(s) to run until the
> specified system pressure is reached, at which point the pump(s) turn off.
>
> One other thing I have noticed is that some electronic ignition systems
> may fire the spark plugs one time when the system is energized. This will
> likely cause the prop to turn if there is a burnable mixture in the
> cylinders. In fact, my Varieze has such a system. A number of times I
> have actually had the engine start spontaneously because of this effect -
> prime with accelerator pump, walk the prop to pull fuel into the
> cylinders, turn on the ignition, and away it goes. So, magnetos aren't
> the only things that will fire unexpectedly. In fact, a mag without an
> impulse couple isn't likely going to spark on its own..
>
> So to get back to the original question, I agree that stopping the fuel
> delivery in some way is generally a good idea. I think turning off the
> pumps while leaving the ignition firing is the best bet, as that should
> dump fuel system pressure, and yield the least burnable mixture in the
> cylinders.
>
> With all that said, everyone working around aircraft should be very
> careful of the propeller, whatever method is used to stop the engine.
> Pilots need to be vigilant to not allow anyone to haphazardly move the
> prop or stand in the prop arc.
>
>
> Regards,
>
> Matt-
>
>> In an Aviation carbed or injected engine, the shutoff method is the
>> same- turn off the fuel. The reason for this is to prevent a fuel/air
>> mixture being left in a cylinder. If a P lead wire is broken and the
>> propeller is turned, it could fire and injure someone. From your
>> question I assume youre installing an auto engine.
>>
>> Auto engines kill the spark. Some might also kill the pressure in the
>> fuel rail. Youre going to have to blas your own trail here.
>>
>> Bruce
>> www.Glasair.org <http://www.glasair.org/>
>> -----Original Message-----
>> From: owner-aeroelectric-list-server@matronics.com
>> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
>> Kenneth Johnson
>> Sent: Tuesday, April 27, 2010 12:45 PM
>> To: aeroelectric-list@matronics.com
>> Subject: AeroElectric-List: stopping engine
>>
>> Aircraft Electrical Gurus,
>> This subject has been presented briefly recently, but I was looking for
>> the opinion of several. This may have an electrical solution of not.
>> The question is: "What is the best way to stop your aircraft engine?
>>
>> In the recent past, at this site I have seen recommended a switch to the
>> fuel pump. Turn off the fuel pump and eventually the engine stops.
>>
>> I rent Cessna 172 and the prefered way to stop the engine is to minimize
>> both the throttle and richness knobs by pulling them out. Technically,
>> what exactly does this do? Could I place a simple ball valve on my fuel
>> rail and phsically close it? Is this what I do on the Cessna 172? The
>> Cessna fuel is fed throught a carburetor and my engine is fuel injected.
>> Does that make a difference?
>>
>> On the automobile engine, when we turn off the engine, are we just
>> closing the switch that provides current to the spark plugs, or is
>> something else involved? Is this what should be done for the aircraft
>> engine?
>>
>> Thanks for your advice.
>>
>> Ken Johnson
>>
>>
>>
>><B -Matt=============
>
>
Message 3
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Matt,
An injector with much of a leak will show up on the way the engine performs,
but some have installed a small orifice (.050") in a bypass line around the
fuel pressure regulator. This small leak is not more than the pump and
regulator can handle, but when the pump is turned off, the line pressure
quickly bleeds off into the tank return line. This would stop any possible
problems from a leaky injector.
Bill B
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Matt
Prather
Sent: Wednesday, April 28, 2010 2:04 PM
Subject: RE: AeroElectric-List: stopping engine
Bill,
My only concern about this (and it's probably a remote concern) is that if
you have a leaking injector, it may dribble fuel into the engine after
shutdown. Otherwise, this is very much analogous to pulling the mixture
to ICO on an aircraft carb or mechanical injection.
Matt-
> Ken,
>
> You didnt say if you have fuel injection or a carb on your Mazda rotary,
> but if you have FI, you can shut off the injectors and the engine will
> immediately stop due to fuel starvation. No fuel will be left in the
> rotor
> faces. The fuel regulator will then immediately open up to keep the fuel
> pressure at your set point, so the fuel pumps will not be adversely
> affected. In fact, this is the condition you will have the regulator and
> pumps in when you set the fuel pressure. This is the way it is designed
> to
> work so no damage will ensue. After the engine stops you can leisurely
> shut
> everything else down. There will be no fuel in the rotors so there will
> be
> no danger if you want to move the prop for whatever reason.
>
> If you have a carb, well, you are on your own.. :>)
>
>
> Bill B
>
>
> _____
>
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kenneth
> Johnson
> Sent: Wednesday, April 28, 2010 12:11 PM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: stopping engine
>
>
> Hi All,
>
> I would like to thank all who responded.
>
>
> It would seem the best reason to stop an engine with fuel starvation would
> be to prevent possible danger from the prop. If a prop was repositioned,
> fuel in a cylinder might ignite, which in turn would turn the prop and
> that
> might hurt someone. In an automobile, if dieseling occurs, no is hurt.
> The
> car is in "Park" or "Neutral."
>
>
> I have a Mazda rotary engine I will be using for my airplane. Eventhough
> this is not a piston engine, the threat of danger from the prop with fuel
> left in the burn chamber still exists. For safety reasons, fuel
> starvation
> would be the best way to stop the engine. Turning off the ignition will
> stop current to the spark plugs, coils, and will turn off the high
> pressure
> fuel pump. However, it would seem that turning off the fuel pump before
> turning off the ignition would be a safer way to eliminate fuel from the
> burn chambers.
>
>
> By using a valve on my fuel rail, I could stop fuel. However, the fuel
> pump
> would still be working and could be damaged. Again, it would seem that
> switching off the fuel pump before the ignition might be the best
> solution.
>
>
> If anyone has a better solution, please post.
>
>
> Thanks,
>
>
> Ken Johnson
>
>
> _____
>
> From: Matt Prather <mprather@spro.net>
> To: aeroelectric-list@matronics.com
> Sent: Tue, April 27, 2010 1:54:43 PM
> Subject: RE: AeroElectric-List: stopping engine
>
> <mprather@spro.net>
>
> I think it's worthwhile to be precise (reduce ambiguity) in matters such
> as this.
>
> I believe many (most?) light airplane POH's specify that engine shutdown
> is accomplished by moving the mixture control to idle-cutoff (ICO).
> Usually this causes the engine to stop running fairly rapidly - in a
> matter of a couple of seconds. Selecting rich mixture and hitting the
> starter usually allows the engine to restart very quickly/easily.
>
> Certainly many airplanes still have Stromberg carbs (or similar) which
> don't have a mixture control effective enough to cause "idle-cutoff". I
> have ridden with pilots of such airplanes who only use the magneto
> switches to stop the engine. One benefit of this procedure is that you
> check to see if you have a "hot mag" on each flight. If the engine stops
> dead, you can be somewhat certain that the p-lead circuit is in working
> condition.
>
> Most (all?) light airplanes also have at least one fuel control valve
> (selector), which can also be used to stop the flow of fuel to the engine.
> On the carbureted engines that I have operated, closing this fuel valve
> does eventually stop the engine, though depending on how low the throttle
> setting is, it might take a few minutes for the float bowl in the carb to
> get low enough to cause the engine to lean-out and die. Usually when I
> pull up to a parking spot, I don't feel like waiting for the carb to
> empty, so I never do this.
>
> If the fuel valve was turned off, on carbureted airplanes with gravity
> feed fuel, turning on the fuel valve and waiting a few moments will refill
> the carb float bowl, at which point the engine may be restarted. For an
> airplane with pump driven fuel, turning on the electric pump will allow
> restarting much faster/sooner than if only the engine driven pump is used.
> Turning on the electric pump is often in the engine start procedure.
>
> In an airplane that depends on a high pressure electric pump, I'm not sure
> it makes sense to "turn off the fuel," if that implies closing some kind
> of fuel valve. It might make more sense to turn off the electric pump(s).
>
> My impression of automotive fuel injection is that turning the key off
> stops power to both the ignition and the fuel pump(s). This leaves
> burnable mixture in the cylinders and intake manifold. In an airplane,
> this method of stopping the engine increases the risk of unexpected prop
> motion. Turning the key to run causes the fuel pump(s) to run until the
> specified system pressure is reached, at which point the pump(s) turn off.
>
> One other thing I have noticed is that some electronic ignition systems
> may fire the spark plugs one time when the system is energized. This will
> likely cause the prop to turn if there is a burnable mixture in the
> cylinders. In fact, my Varieze has such a system. A number of times I
> have actually had the engine start spontaneously because of this effect -
> prime with accelerator pump, walk the prop to pull fuel into the
> cylinders, turn on the ignition, and away it goes. So, magnetos aren't
> the only things that will fire unexpectedly. In fact, a mag without an
> impulse couple isn't likely going to spark on its own..
>
> So to get back to the original question, I agree that stopping the fuel
> delivery in some way is generally a good idea. I think turning off the
> pumps while leaving the ignition firing is the best bet, as that should
> dump fuel system pressure, and yield the least burnable mixture in the
> cylinders.
>
> With all that said, everyone working around aircraft should be very
> careful of the propeller, whatever method is used to stop the engine.
> Pilots need to be vigilant to not allow anyone to haphazardly move the
> prop or stand in the prop arc.
>
>
> Regards,
>
> Matt-
>
>> In an Aviation carbed or injected engine, the shutoff method is the
>> same- turn off the fuel. The reason for this is to prevent a fuel/air
>> mixture being left in a cylinder. If a P lead wire is broken and the
>> propeller is turned, it could fire and injure someone. From your
>> question I assume youre installing an auto engine.
>>
>> Auto engines kill the spark. Some might also kill the pressure in the
>> fuel rail. Youre going to have to blas your own trail here.
>>
>> Bruce
>> www.Glasair.org <http://www.glasair.org/>
>> -----Original Message-----
>> From: owner-aeroelectric-list-server@matronics.com
>> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
>> Kenneth Johnson
>> Sent: Tuesday, April 27, 2010 12:45 PM
>> To: aeroelectric-list@matronics.com
>> Subject: AeroElectric-List: stopping engine
>>
>> Aircraft Electrical Gurus,
>> This subject has been presented briefly recently, but I was looking for
>> the opinion of several. This may have an electrical solution of not.
>> The question is: "What is the best way to stop your aircraft engine?
>>
>> In the recent past, at this site I have seen recommended a switch to the
>> fuel pump. Turn off the fuel pump and eventually the engine stops.
>>
>> I rent Cessna 172 and the prefered way to stop the engine is to minimize
>> both the throttle and richness knobs by pulling them out. Technically,
>> what exactly does this do? Could I place a simple ball valve on my fuel
>> rail and phsically close it? Is this what I do on the Cessna 172? The
>> Cessna fuel is fed throught a carburetor and my engine is fuel injected.
>> Does that make a difference?
>>
>> On the automobile engine, when we turn off the engine, are we just
>> closing the switch that provides current to the spark plugs, or is
>> something else involved? Is this what should be done for the aircraft
>> engine?
>>
>> Thanks for your advice.
>>
>> Ken Johnson
>>
>>
>>
>><B -Matt=============
>
>
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Ken, you didn=92t say,
But if you are using electronic fuel injectors with your rotary engine,
a
power cut off switch to the injectors will instantly stop injection even
with your pumps still running. That is the method I use for shut down
and
there is no fuel left in combustion chamber nor any potential to damage
the
fuel pumps by running them dry.
http://www.flyrotary.com/
You may want to consider joining our FlyRotary list ' there are many
flying
who have solved most problems you are likely to encounter and the
information is there.
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
<http://www.andersonee.com> http://www.andersonee.com
<http://www.dmack.net/mazda/index.html>
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
<http://members.cox.net/rogersda/rotary/configs.htm>
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
<http://www.dmack.net/mazda/index.html>
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Kenneth
Johnson
Sent: Wednesday, April 28, 2010 12:11 PM
Subject: Re: AeroElectric-List: stopping engine
Hi All,
I would like to thank all who responded.
It would seem the best reason to stop an engine with fuel starvation
would
be to prevent possible danger from the prop. If a prop was
repositioned,
fuel in a cylinder might ignite, which in turn would turn the prop and
that
might hurt someone. In an automobile, if dieseling occurs, no is hurt.
The
car is in "Park" or "Neutral."
I have a Mazda rotary engine I will be using for my airplane.
Eventhough
this is not a piston engine, the threat of danger from the prop with
fuel
left in the burn chamber still exists. For safety reasons, fuel
starvation
would be the best way to stop the engine. Turning off the ignition will
stop current to the spark plugs, coils, and will turn off the high
pressure
fuel pump. However, it would seem that turning off the fuel pump before
turning off the ignition would be a safer way to eliminate fuel from the
burn chambers.
By using a valve on my fuel rail, I could stop fuel. However, the fuel
pump
would still be working and could be damaged. Again, it would seem that
switching off the fuel pump before the ignition might be the best
solution.
If anyone has a better solution, please post.
Thanks,
Ken Johnson
_____
From: Matt Prather <mprather@spro.net>
Sent: Tue, April 27, 2010 1:54:43 PM
Subject: RE: AeroElectric-List: stopping engine
<mprather@spro.net>
I think it's worthwhile to be precise (reduce ambiguity) in matters such
as this.
I believe many (most?) light airplane POH's specify that engine shutdown
is accomplished by moving the mixture control to idle-cutoff (ICO).
Usually this causes the engine to stop running fairly rapidly - in a
matter of a couple of seconds. Selecting rich mixture and hitting the
starter usually allows the engine to restart very quickly/easily.
Certainly many airplanes still have Stromberg carbs (or similar) which
don't have a mixture control effective enough to cause "idle-cutoff". I
have ridden with pilots of such airplanes who only use the magneto
switches to stop the engine. One benefit of this procedure is that you
check to see if you have a "hot mag" on each flight. If the engine
stops
dead, you can be somewhat certain that the p-lead circuit is in working
condition.
Most (all?) light airplanes also have at least one fuel control valve
(selector), which can also be used to stop the flow of fuel to the
engine.
On the carbureted engines that I have operated, closing this fuel valve
does eventually stop the engine, though depending on how low the
throttle
setting is, it might take a few minutes for the float bowl in the carb
to
get low enough to cause the engine to lean-out and die. Usually when I
pull up to a parking spot, I don't feel like waiting for the carb to
empty, so I never do this.
If the fuel valve was turned off, on carbureted airplanes with gravity
feed fuel, turning on the fuel valve and waiting a few moments will
refill
the carb float bowl, at which point the engine may be restarted. For an
airplane with pump driven fuel, turning on the electric pump will allow
restarting much faster/sooner than if only the engine driven pump is
used.
Turning on the electric pump is often in the engine start procedure.
In an airplane that depends on a high pressure electric pump, I'm not
sure
it makes sense to "turn off the fuel," if that implies closing some kind
of fuel valve. It might make more sense to turn off the electric
pump(s).
My impression of automotive fuel injection is that turning the key off
stops power to both the ignition and the fuel pump(s). This leaves
burnable mixture in the cylinders and intake manifold. In an airplane,
this method of stopping the engine increases the risk of unexpected prop
motion. Turning the key to run causes the fuel pump(s) to run until the
specified system pressure is reached, at which point the pump(s) turn
off.
One other thing I have noticed is that some electronic ignition systems
may fire the spark plugs one time when the system is energized. This
will
likely cause the prop to turn if there is a burnable mixture in the
cylinders. In fact, my Varieze has such a system. A number of times I
have actually had the engine start spontaneously because of this effect
-
prime with accelerator pump, walk the prop to pull fuel into the
cylinders, turn on the ignition, and away it goes. So, magnetos aren't
the only things that will fire unexpectedly. In fact, a mag without an
impulse couple isn't likely going to spark on its own..
So to get back to the original question, I agree that stopping the fuel
delivery in some way is generally a good idea. I think turning off the
pumps while leaving the ignition firing is the best bet, as that should
dump fuel system pressure, and yield the least burnable mixture in the
cylinders.
With all that said, everyone working around aircraft should be very
careful of the propeller, whatever method is used to stop the engine.
Pilots need to be vigilant to not allow anyone to haphazardly move the
prop or stand in the prop arc.
Regards,
Matt-
> In an Aviation carb=92ed or injected engine, the shutoff method is the
> same- turn off the fuel. The reason for this is to prevent a fuel/air
> mixture being left in a cylinder. If a P lead wire is broken and the
> propeller is turned, it could fire and injure someone. From your
> question I assume you=92re installing an auto engine.
>
> Auto engines kill the spark. Some might also kill the pressure in the
> fuel rail. You=92re going to have to blas=E9 your own trail here.
>
> Bruce
> www.Glasair.org <http://www.glasair.org/>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> Kenneth Johnson
> Sent: Tuesday, April 27, 2010 12:45 PM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: stopping engine
>
> Aircraft Electrical Gurus,
> This subject has been presented briefly recently, but I was looking
for
> the opinion of several. This may have an electrical solution of not.
> The question is: "What is the best way to stop your aircraft engine?
>
> In the recent past, at this site I have seen recommended a switch to
the
> fuel pump. Turn off the fuel pump and eventually the engine stops.
>
> I rent Cessna 172 and the prefered way to stop the engine is to
minimize
> both the throttle and richness knobs by pulling them out.
Technically,
> what exactly does this do? Could I place a simple ball valve on my
fuel
> rail and phsically close it? Is this what I do on the Cessna 172?
The
> Cessna fuel is fed throught a carburetor and my engine is fuel
injected.
> Does that make a difference?
>
> On the automobile engine, when we turn off the engine, are we just
> closing the switch that provides current to the spark plugs, or is
> something else involved? Is this what should be done for the aircraft
> engine?
>
> Thanks for your advice.
>
> Ken Johnson
>
>
><B -Matt=============
Message 5
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| Subject: | IVO Prop Current Limiter/Electronic Circuit Breaker |
It took a bit more 'praying' than I anticipated
and I'm only 99.6% sure that my confidence in
having met design goals have been met. But I'll
invite other 'electron herders' on the List
to review the following and see if I've stubbed
my toe anywhere:
See:
http://aeroelectric.com/Pictures/Schematics/IVO-Prop_Pitch_Controller.pdf
Design goals:
Provide absolute current limit on the order of 9A:
Q114 is a power FET that saturates with bias
through R104, R105 and D109 when power is applied
through "M" connections that sense motor power.
Voltage drop across R117/R118 is monitored through
R116 causing Q115 to turn on when drop across the
R117/118 exceeds Vbe of Q115. This is approx .6
volts. When Q115 turns on, it starves Q114 of gate
drive and causes it to become a constant current
generator with calibration set by the combination
of R117/R118.
Any time the constant current loop is active,
LED D109 will be illuminated. D109 will flash
each time the prop pitch motor is energized
and the system becomes an active inrush current
limiter.
Limit the duration of the current limit mode to
100-200 mS whereupon the system goes open circuit
and removes power from the motor:
At any time the current limiter is active,
Q115 collector current through R105 will turn
on Q103 causing the collector to pull up to
the supply rail. This causes C112 to charge
through R106 until zener D110 conducts at about
8V. This event will occur approximately 120 mS
after onset of current limit.
When D110 conducts, it pulls the base of Q115
more positive causing the Q115/Q103 pair to
"latch up" not unlike an SCR. When the latching
event occurs, the collector of Q115 pulls to
a few millivolts above ground depriving Q114
of all gate drive.
Normal operation:
D109 will flash each time the motor control switch
is closed due to motor inrush current being
electronically limited. D109 will also flash a
bit longer (about 120 mS) when the prop pitch motor
reaches the mechanical stop and the current limit is
invoked.
As long as the prop pitch motor is powered
D108 will be illuminated. When the prop
pitch system reaches a mechanical limit and
the control switch is NOT relaxed, D019 flashes
for about 120 mS and D108 goes dark.
Releasing the motor control switch removes
power from the latching loop and discharges
C112 through R119, R104, BC junction Q103,
and R106.
The system spends so little time in I-limit
mode that Q114 does not require a heat-sink.
D109 and D108 staying on together indicates
a malfunction and the motor control switch
needs to be released within a second or so
to avoid over-heat damage to Q114.
Don't anyone run out and build this yet. Let's
thrash the bushes a bit for rats.
Bob . . .
Message 6
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| Subject: | Re: stopping engine |
We're off in the weeds a bit as far as Aero Electrics..
I'm pretty sure that the Marvel Schebler carbs pass all of the fuel
through the main metering valve - even the idle circuit. Thus, pulling
the mixture to ICO on these units does, in fact, positively stop fuel
flow.
The Stromberg carbs, and those commonly installed on Rotax engines work as
you suggested. I believe these carbs are known variously as "altitude
compensating".
My impression of the Manual Mixture Control for the Holley is that it
works much like the Schebler - positively controlling fuel flow, not by
controlling venting of the float chamber. I could be mistaken here.
Regards,
Matt-
> <ceengland@bellsouth.net>
>
> A couple of thoughts.
>
> With electronic automotive injection, killing the injector power will
> stop the injectors, but the fuel rail will still be pressurized. If an
> injector is a bit leaky, fuel can still make it to the combustion
> chamber after shutdown. Some guys provide a tiny bleed hole that
> bypasses the regulator so the fuel rail will depressurize a minute or so
> after shutdown (probably overkill, but there it is).
>
> On the subject of traditional a/c engines with carbs, there is a
> possible misconception buried below (I hate RPN posting....). I read
> about the following somewhere & was surprised, but cutaway drawings of
> some a/c carbs seem to support the story. I believe that the McNeilly
> (sp?) leaning block for Holley carbs works this way, too, and the
> technique has been used to lean some motorcycle carbs on alternative
> engines. Here's the 'story':
>
> On at least some a/c carbs, the mixture control is actually controlling
> the vent to the fuel bowl on the carb. Pulling mixture to idle cutoff on
> those carbs just causes the 'head' (air pressure+fuel weight) on the
> fuel in the bowl to drop until it equals the absolute pressure in the
> venturi, stopping flow. Once the engine stops, pressure can equalize at
> ambient. If the prop spins after that happens, and the mags are on, the
> engine can fire because there's still fuel available & there's now a
> (short term) normal 'head' of ambient pressure on the fuel in the bowl.
>
> Charlie
>
Message 7
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|
| Subject: | Re: stopping engine |
I will add a correction to the Mc Neilly mixture block for Holley carbs.
. Tom Mc Neilly designed the block to act like a variable main jet, not
to alter float bowl pressure... Some 2 and 4 stroke snowmobile motors u
se the bowl pressure method to trick the carb into thinking it is at a d
ifferent altitude..... Just for the record....
Ps... I LOVE my Mc Neilly mixture block on my V-8 powered experimental.
It works sooo good. !!!!!!
Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: Charlie England <ceengland@bellsouth.net>
Subject: Re: AeroElectric-List: stopping engine
south.net>
A couple of thoughts.
With electronic automotive injection, killing the injector power will
stop the injectors, but the fuel rail will still be pressurized. If an
injector is a bit leaky, fuel can still make it to the combustion
chamber after shutdown. Some guys provide a tiny bleed hole that
bypasses the regulator so the fuel rail will depressurize a minute or so
after shutdown (probably overkill, but there it is).
On the subject of traditional a/c engines with carbs, there is a
possible misconception buried below (I hate RPN posting....). I read
about the following somewhere & was surprised, but cutaway drawings of
some a/c carbs seem to support the story. I believe that the McNeilly
(sp?) leaning block for Holley carbs works this way, too, and the
technique has been used to lean some motorcycle carbs on alternative
engines. Here's the 'story':
On at least some a/c carbs, the mixture control is actually controlling
the vent to the fuel bowl on the carb. Pulling mixture to idle cutoff on
those carbs just causes the 'head' (air pressure+fuel weight) on the
fuel in the bowl to drop until it equals the absolute pressure in the
venturi, stopping flow. Once the engine stops, pressure can equalize at
ambient. If the prop spins after that happens, and the mags are on, the
engine can fire because there's still fuel available & there's now a
(short term) normal 'head' of ambient pressure on the fuel in the bowl.
Charlie
On 4/28/2010 11:32 AM, Mike Fontenot wrote:
> I have a GEO engine, EFI is the EC2 system, with 2 fuel pumps going
> into a single line, then to the fuel rail. In that line is a 3 way
> valve that I can use to bypass the rail and spill back into the fuel
> tank. Turning off the engine by starving the fuel, yet keeping the
> pumps running smoothly works quite well.
>
> On Wed, Apr 28, 2010 at 10:11 AM, Kenneth Johnson
> <kjohnsondds@yahoo.com <mailto:kjohnsondds@yahoo.com>> wrote:
>
> Hi All,
> I would like to thank all who responded.
> It would seem the best reason to stop an engine with fuel
> starvation would be to prevent possible danger from the prop. If
> a prop was repositioned, fuel in a cylinder might ignite, which in
> turn would turn the prop and that might hurt someone. In an
> automobile, if dieseling occurs, no is hurt. The car is in "Park"
> or "Neutral."
> I have a Mazda rotary engine I will be using for my airplane.
> Eventhough this is not a piston engine, the threat of danger from
> the prop with fuel left in the burn chamber still exists. For
> safety reasons, fuel starvation would be the best way to stop the
> engine. Turning off the ignition will stop current to the spark
> plugs, coils, and will turn off the high pressure fuel pump.
> However, it would seem that turning off the fuel pump before
> turning off the ignition would be a safer way to eliminate fuel
> from the burn chambers.
> By using a valve on my fuel rail, I could stop fuel. However, the
> fuel pump would still be working and could be damaged. Again, it
> would seem that switching off the fuel pump before the
> ignition might be the best solution.
> If anyone has a better solution, please post.
> Thanks,
> Ken Johnson
>
> ------------------------------------------------------------------
------
> *From:* Matt Prather <mprather@spro.net <mailto:mprather@spro.net>
>
> *To:* aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> *Sent:* Tue, April 27, 2010 1:54:43 PM
> *Subject:* RE: AeroElectric-List: stopping engine
>
> <mprather@spro.net <mailto:mprather@spro.net>>
>
> I think it's worthwhile to be precise (reduce ambiguity) in
> matters such
> as this.
>
> I believe many (most?) light airplane POH's specify that engine
> shutdown
> is accomplished by moving the mixture control to idle-cutoff (ICO)
.
> Usually this causes the engine to stop running fairly rapidly - in
a
> matter of a couple of seconds. Selecting rich mixture and hitting
the
> starter usually allows the engine to restart very quickly/easily.
>
> Certainly many airplanes still have Stromberg carbs (or similar) w
hich
> don't have a mixture control effective enough to cause
> "idle-cutoff". I
> have ridden with pilots of such airplanes who only use the magneto
> switches to stop the engine. One benefit of this procedure is
> that you
> check to see if you have a "hot mag" on each flight. If the
> engine stops
> dead, you can be somewhat certain that the p-lead circuit is in
> working
> condition.
>
> Most (all?) light airplanes also have at least one fuel control va
lve
> (selector), which can also be used to stop the flow of fuel to the
> engine.
> On the carbureted engines that I have operated, closing this fuel
> valve
> does eventually stop the engine, though depending on how low the
> throttle
> setting is, it might take a few minutes for the float bowl in the
> carb to
> get low enough to cause the engine to lean-out and die. Usually
> when I
> pull up to a parking spot, I don't feel like waiting for the carb
to
> empty, so I never do this.
>
> If the fuel valve was turned off, on carbureted airplanes with gra
vity
> feed fuel, turning on the fuel valve and waiting a few moments
> will refill
> the carb float bowl, at which point the engine may be restarted.
> For an
> airplane with pump driven fuel, turning on the electric pump will
> allow
> restarting much faster/sooner than if only the engine driven pump
> is used.
> Turning on the electric pump is often in the engine start procedur
e.
>
> In an airplane that depends on a high pressure electric pump, I'm
> not sure
> it makes sense to "turn off the fuel," if that implies closing
> some kind
> of fuel valve. It might make more sense to turn off the electric
> pump(s).
>
> My impression of automotive fuel injection is that turning the key
off
> stops power to both the ignition and the fuel pump(s). This leave
s
> burnable mixture in the cylinders and intake manifold. In an
> airplane,
> this method of stopping the engine increases the risk of
> unexpected prop
> motion. Turning the key to run causes the fuel pump(s) to run
> until the
> specified system pressure is reached, at which point the pump(s)
> turn off.
>
> One other thing I have noticed is that some electronic ignition
> systems
> may fire the spark plugs one time when the system is energized.
> This will
> likely cause the prop to turn if there is a burnable mixture in th
e
> cylinders. In fact, my Varieze has such a system. A number of
> times I
> have actually had the engine start spontaneously because of this
> effect -
> prime with accelerator pump, walk the prop to pull fuel into the
> cylinders, turn on the ignition, and away it goes. So, magnetos
> aren't
> the only things that will fire unexpectedly. In fact, a mag
> without an
> impulse couple isn't likely going to spark on its own..
>
> So to get back to the original question, I agree that stopping
> the fuel
> delivery in some way is generally a good idea. I think turning
> off the
> pumps while leaving the ignition firing is the best bet, as that
> should
> dump fuel system pressure, and yield the least burnable mixture in
the
> cylinders.
>
> With all that said, everyone working around aircraft should be ver
y
> careful of the propeller, whatever method is used to stop the engi
ne.
> Pilots need to be vigilant to not allow anyone to haphazardly move
the
> prop or stand in the prop arc.
>
>
> Regards,
>
> Matt-
>
> > In an Aviation carb=92ed or injected engine, the shutoff method
is the
> > same- turn off the fuel. The reason for this is to prevent a
> fuel/air
> > mixture being left in a cylinder. If a P lead wire is broken and
the
> > propeller is turned, it could fire and injure someone. From your
> > question I assume you=92re installing an auto engine.
> >
> > Auto engines kill the spark. Some might also kill the pressure
> in the
> > fuel rail. You=92re going to have to blas=E9 your own trail here
.
> >
> > Bruce
> > www.Glasair.org <http://www.glasair.org/>
> > -----Original Message-----
> > From: owner-aeroelectric-list-server@matronics.com
> <mailto:owner-aeroelectric-list-server@matronics.com>
> > [mailto:owner-aeroelectric-list-server@matronics.com
> <mailto:owner-aeroelectric-list-server@matronics.com>] On Behalf O
f
> > Kenneth Johnson
> > Sent: Tuesday, April 27, 2010 12:45 PM
> > To: aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> > Subject: AeroElectric-List: stopping engine
> >
> > Aircraft Electrical Gurus,
> > This subject has been presented briefly recently, but I was
> looking for
> > the opinion of several. This may have an electrical solution of
> not.
> > The question is: "What is the best way to stop your aircraft eng
ine?
> >
> > In the recent past, at this site I have seen recommended a
> switch to the
> > fuel pump. Turn off the fuel pump and eventually the engine sto
ps.
> >
> > I rent Cessna 172 and the prefered way to stop the engine is to
> minimize
> > both the throttle and richness knobs by pulling them out.
> Technically,
> > what exactly does this do? Could I place a simple ball valve on
> my fuel
> > rail and phsically close it? Is this what I do on the Cessna
> 172? The
> > Cessna fuel is fed throught a carburetor and my engine is fuel
> injected.
> > Does that make a difference?
> >
> > On the automobile engine, when we turn off the engine, are we ju
st
> > closing the switch that provides current to the spark plugs, or
is
> > something else involved? Is this what should be done for the
> aircraft
> > engine?
> >
> > Thanks for your advice.
> >
> > Ken Johnson
> >
> >
> >
> >
>
>
> *
>
> ist" target="_blank">http://www.matronics.com/Navigator?AeroElec
tric-List
> tp://forums.matronics.com
> _blank">http://www.matronics.com/contribution
>
> *
>
>
> --
> Mike
>
> ========================
=======
> Mike Fontenot
> Apex Consulting & Services LLC
> Lakewood, Colorado
> 303 / 731-6645
> mikef AT apexconsultingservices DOT com
> ======
> *
>
>
> *
========================
===========
========================
===========
========================
===========
========================
===========
____________________________________________________________
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Message 8
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| Subject: | Check out THIS structural test event |
A client of mine has some hardware on this airplane.
Suppliers to the program were alerted to a major milestone
in static testing for the airframe. See:
http://tinyurl.com/y5uqmpa
Bob . . .
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