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rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Wed Jul 15, 2009 8:03 pm Post subject: 447 problem

I've been flying in front of a 912ULS for many years, but am now also flying (again) in front of a 447... and I'm already missing the reliability!



Ok, so, I'm flying along for 40 minutes, and everything is cool.  I'm flying straight-and-level, no throttle changes, just cruising, then suddenly the rpms drop 1000rpm, from about 6200 to 5200, then after a moment, it surges back up to 6200.  Then about 3-4 seconds later, it does the same thing.  Luckily, I'm near the airport, so I make a bee-line to the runway and land safely.

 

As I land, at the lower throttle settings, it seems okay.  After I land, it seems to work fine while I taxi.



I get back to the hangar and let it cool off.  The tank was almost dry (had about a gallon left) by that point, so I put in fresh gas (always using Mr. Funnel).  After it's cooled off, I try to start it, and it starts right up.  It idles normally, then I taxi out and try it again.  I circle the airport 3 or 4 times, at around 600-700 feet, and after 10 minutes the wind starts coming up, so I decide I'll cut this test flight short.  Right about then, it starts doing it again... I hadn't made any altitude changes, throttle changes, and the tank this time was full.  So, it's not bad fuel.

 

The system pressurizes okay when I use the squeeze bulb and, as I said, it starts right up.  No other indications that I can see or hear of anything wrong.  I'm going to check the plugs tomorrow, but it runs just fine.

 

My only guess is that maybe the mechanical fuel pump is on it's last legs and can't keep the bowl full.  I've got a Facet pump that I think I'll plumb in parallel and turn it on throughout a flight, to see if that helps.

 

Anyone else have any ideas what it might be?



  -- Robert



  [quote][b]

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

The BaronVonEvil

Joined: 23 Jun 2006
Posts: 76
Location: Walla Walla, WA.

Posted: Wed Jul 15, 2009 9:18 pm Post subject: 447 problem

Hi Bob,

  

 You may wish to check the float bowl to see if  there is anything floating around in there. If the pump is failing, there could  be bits of rubber diaphragm getting into the bowl.

  

 It seems now matter how many filters you have, dirt  always seems to get past them.

  

 Hope this helps

  

 BaronVonEvil

 Firestar II

 Rotax 447

 [quote]   ---

mdnanwelch7(at)hotmail.co
Guest

Posted: Thu Jul 16, 2009 2:53 am Post subject: 447 problem

Bob C

  

   Your experience here sounds similar to an experience I had one time C and we found the problem to be debris in the fuel line.  I think what Carlos suggested is a good candidate to check for C too.

  

   If your engine runs for reasonably long periods of time....and then this happens C I am not lead to believe it is your fuel pump.  IMO C an intermittent problem like the one you're describing sounds most likely like occational fuel starvation C or something disrupting the normal fuel flow.    Just my thoughts.....

  

 Mike Welch

 MkIII

  

  Date: Wed C 15 Jul 2009 22:58:30 -0500

Subject: 447 problem

From: rlaird(at)cavediver.com

To: kolb-list(at)matronics.com



I've been flying in front of a 912ULS for many years C but am now also flying (again) in front of a 447... and I'm already missing the reliability!



Ok C so C I'm flying along for 40 minutes C and everything is cool.  I'm flying straight-and-level C no throttle changes C just cruising C then suddenly the rpms drop 1000rpm C from about 6200 to 5200 C then after a moment C it surges back up to 6200.  Then about 3-4 seconds later C it does the same thing.  Luckily C I'm near the airport C so I make a bee-line to the runway and land safely.



As I land C at the lower throttle settings C it seems okay.  After I land C it seems to work fine while I taxi.



I get back to the hangar and let it cool off.  The tank was almost dry (had about a gallon left) by that point C so I put in fresh gas (always using Mr. Funnel).  After it's cooled off C I try to start it C and it starts right up.  It idles normally C then I taxi out and try it again.  I circle the airport 3 or 4 times C at around 600-700 feet C and after 10 minutes the wind starts coming up C so I decide I'll cut this test flight short.  Right about then C it starts doing it again... I hadn't made any altitude changes C throttle changes C and the tank this time was full.  So C it's not bad fuel.



The system pressurizes okay when I use the squeeze bulb and C as I said C it starts right up.  No other indications that I can see or hear of anything wrong.  I'm going to check the plugs tomorrow C but it runs just fine.



My only guess is that maybe the mechanical fuel pump is on it's last legs and can't keep the bowl full.  I've got a Facet pump that I think I'll plumb in parallel and turn it on throughout a flight C to see if that helps.



Anyone else have any ideas what it might be?



  -- Robert



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Posted: Thu Jul 16, 2009 2:53 am Post subject: 447 problem

I had similar symptoms at one time, once ending in an  off field deadstick landing.  

     For me, it was a flaw in the primer  squeeze bulb.  It would restrict the fuel flow at times.  I learned  this when I finally had the symptoms appear during a ground runup, and saw the  fuel lines flatten out as the fuel pump starved.

      Wasn't the fault of the 447  at all.

    My setup on my UltraStar allowed me to  just eliminate the primer squeeze bulb, and allow gravity and the mechanical  fuel pump to do everything.

  

  In a message dated 7/16/2009 12:18:42 A.M. Central Daylight Time,  grageda(at)innw.net writes:

 [quote]   Hi Bob,

    

   You may wish to check the float bowl to see if    there is anything floating around in there. If the pump is failing, there    could be bits of rubber diaphragm getting into the bowl.

    

   It seems now matter how many filters you have,    dirt always seems to get past them.

    

   Hope this helps

    

   BaronVonEvil

   Firestar II

   Rotax 447

   [quote]     ---

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Thu Jul 16, 2009 3:32 am Post subject: 447 problem

Hi Carlos!



Thanks for the note.  Actually, the float bowl is probably the first thing I checked, but just forgot to mention it... sorry!  I do like filters after the primer bulb, in case parts of it breaks off, but I thought the mechanical fuel pump had a metal diaphragm?

 

  -- Robert



On Thu, Jul 16, 2009 at 12:17 AM, Carlos <grageda(at)innw.net (grageda(at)innw.net)> wrote:

[quote]        Hi Bob,

  

 You may wish to check the float bowl to see if  there is anything floating around in there. If the pump is failing, there could  be bits of rubber diaphragm getting into the bowl.

  

 It seems now matter how many filters you have, dirt  always seems to get past them.

  

 Hope this helps

  

 BaronVonEvil

 Firestar II

 Rotax 447

 [quote]   ---

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Jul 16, 2009 5:12 am Post subject: Re: 447 problem

Hi Robert, Another thing to check is the pulse line length. Make sure it's no longer than a foot and preferably 10" or less. Too long of a pulse line is a common source of extremely bizarre behaving fuel starvation events as it weakens the driving action on the pneumatic pump.



I'd also check for scuffing on the piston skirts through the exhaust ports. Fuel starvation events can cause this and in fact the slowdowns could be due to a slight siezure as well....



LS

_________________
LS
Titan II SS

aslsa.rng(at)gmail.com
Guest

Posted: Thu Jul 16, 2009 5:24 am Post subject: 447 problem

Bob, Dump the primer bulb from the system. The last one I had on a plane failed on takeoff. Fortunately I had 2000 ft of runway left and it was a non incident. Thinking I was going to replace it I bought two new ones. One was dead right out of the package and the other is now confined to syphon duty where it can't hurt me. Rotax used to recommend putting the Facet pump in parallel but has refined that view in light of 20+ years of experience and they're now okay with a series installation. Series installation is just a cleaner installation and I don't believe there's a failure mode of the Facet that can block the fuel system. Unless you have a very long draw the Mikuni pump will do just fine on it's own even with the Facet in the line. I've run mine both ways, Facet on and off, in flight and can't notice any difference.

 



Rick Girard

do not archive

On Thu, Jul 16, 2009 at 6:29 AM, Robert Laird <rlaird(at)cavediver.com (rlaird(at)cavediver.com)> wrote: [quote]Hi Carlos!



Thanks for the note.  Actually, the float bowl is probably the first thing I checked, but just forgot to mention it... sorry!  I do like filters after the primer bulb, in case parts of it breaks off, but I thought the mechanical fuel pump had a metal diaphragm?

  

  -- Robert



On Thu, Jul 16, 2009 at 12:17 AM, Carlos <grageda(at)innw.net (grageda(at)innw.net)> wrote:



 [quote]        Hi Bob,

  

 You may wish to check the float bowl to see if  there is anything floating around in there. If the pump is failing, there could  be bits of rubber diaphragm getting into the bowl.

  

 It seems now matter how many filters you have, dirt  always seems to get past them.

  

 Hope this helps

  

 BaronVonEvil

 Firestar II

 Rotax 447

 

[quote]   ---

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Thu Jul 16, 2009 5:42 am Post subject: 447 problem

Rick --



The primer bulb has a bypass so even if it had 100% blockage, the fuel would still flow to the fuel pump.  Having said that, I don't like primer bulbs as a rule, and will probably get rid of it, but I'd like to cure this problem first.  I figure if the Facet pump in parallel (or series) would make the problem go away, then I'll then chuck the primer bulb and get a new mechanical pump, too.

 

Thanks!



  -- Robert

On Thu, Jul 16, 2009 at 8:22 AM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:

[quote] Bob, Dump the primer bulb from the system. The last one I had on a plane failed on takeoff. Fortunately I had 2000 ft of runway left and it was a non incident. Thinking I was going to replace it I bought two new ones. One was dead right out of the package and the other is now confined to syphon duty where it can't hurt me.  Rotax used to recommend putting the Facet pump in parallel but has refined that view in light of 20+ years of experience and they're now okay with a series installation. Series installation is just a cleaner installation and I don't believe there's a failure mode of the Facet that can block the fuel system. Unless you have a very long draw the Mikuni pump will do just fine on it's own even with the Facet in the line. I've run mine both ways, Facet on and off, in flight and can't notice any difference.

  



Rick Girard

do not archive



On Thu, Jul 16, 2009 at 6:29 AM, Robert Laird <rlaird(at)cavediver.com (rlaird(at)cavediver.com)> wrote:

 

 [quote]

Hi Carlos!



Thanks for the note.  Actually, the float bowl is probably the first thing I checked, but just forgot to mention it... sorry!  I do like filters after the primer bulb, in case parts of it breaks off, but I thought the mechanical fuel pump had a metal diaphragm?

   

  -- Robert





On Thu, Jul 16, 2009 at 12:17 AM, Carlos <grageda(at)innw.net (grageda(at)innw.net)> wrote:

 

 



[quote]       

 Hi Bob,

  

 You may wish to check the float bowl to see if  there is anything floating around in there. If the pump is failing, there could  be bits of rubber diaphragm getting into the bowl.

  

 It seems now matter how many filters you have, dirt  always seems to get past them.

  

 Hope this helps

  

 BaronVonEvil

 Firestar II

 Rotax 447

 

[quote]   ---

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Thu Jul 16, 2009 5:47 am Post subject: 447 problem

Lucien --



Piston skirt scuffing, eh?  That's a new one on me!  Thanks, I'll check it out.



The pulse line length is about 12 inches... and the engine has over 200 hours on it with this plumbing configuration, so I have to doubt it's the way things are configured.  It's not impossible that the pulse line itself might have a pinhole leak somewhere, or weakening of the line, so, I think I'll replace it.

 

Thanks for the suggestions!



  -- Robert

On Thu, Jul 16, 2009 at 8:12 AM, lucien <lstavenhagen(at)hotmail.com (lstavenhagen(at)hotmail.com)> wrote:

 [quote]--> Kolb-List message posted by: "lucien" <lstavenhagen(at)hotmail.com (lstavenhagen(at)hotmail.com)>

  

 Another thing to check is the pulse line length. Make sure it's no longer than a foot and preferably 10" or less. Too long of a pulse line is a common source of extremely bizarre behaving fuel starvation events as it weakens the driving action on the pneumatic pump.

  

 I'd also check for scuffing on the piston skirts through the exhaust ports. Fuel starvation events can cause this and in fact the slowdowns could be due to a slight siezure as well....

 

 LS

 

 --------

 LS

 Titan II SS

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=253314#253314

 

 

 

 

 

 

 

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 http://forums.matronics.com

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 le, List Admin.

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 [b]

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Jul 16, 2009 6:04 am Post subject: Re: 447 problem

 	  rlaird wrote: 	
		  Lucien --



Piston skirt scuffing, eh?ï¿½ That's a new one on me!ï¿½ Thanks, I'll check it out.



The pulse line length is about 12 inches... and the engine has over 200 hours on it with this plumbing configuration, so I have to doubt it's the way things are configured.ï¿½ It's not impossible that the pulse line itself might have a pinhole leak somewhere, or weakening of the line, so, I think I'll replace it.

 

Thanks for the suggestions!



ï¿½ -- Robert

	




Hi Robert,

12" is fine, tho of course you want to use the good tygothane pulse line on it which has the firm walls. If it's regular fuel line, I'd replace it with pulse line just to be safe.



I was told years ago by Tom Olenik to check for scuffing any time the engine experiences any kind of slow down or stoppage in the air no matter what the cause or how short in duration it was. Because our 2-strokes are putting out high power pretty much all the time the chances of scuffing from even a minute interruption in fuel/oil flow is a lot higher than it would otherwise be.  



As for the squeeze bulb, the best way to eliminate it is to install a primer system and do away with the chokes (or just leave them closed at all times). I always dropped a dedicated line for the primer rather than "T"-ing off the main fuel line - i.e. get a length of 1/8" brass tubing from the HW store (IIRC it's 1/8"), drill a hole in the top of the tank, put the tubing in till it's about 1" above the bottom of the tank and attach the primer line with a tie wrap to the top of the tubing flush with the surface of the tank. 



The primer eliminates the need to fill the float bowls prior to start, since even one shot of the primer fuels the motor enough at startup for the pump to hoover up enough gas to fill the bowls.



This greatly simplifies the fuel line as the only cut you need in it is for the fuel filter and nothing else to clog or introduce drag....



LS

_________________
LS
Titan II SS

aslsa.rng(at)gmail.com
Guest

Posted: Thu Jul 16, 2009 10:52 am Post subject: 447 problem

Robert, Your system is better engineered than mine was.



Rick

do not archive



On Thu, Jul 16, 2009 at 8:42 AM, Robert Laird <rlaird(at)cavediver.com (rlaird(at)cavediver.com)> wrote:

 [quote]Rick --



The primer bulb has a bypass so even if it had 100% blockage, the fuel would still flow to the fuel pump.  Having said that, I don't like primer bulbs as a rule, and will probably get rid of it, but I'd like to cure this problem first.  I figure if the Facet pump in parallel (or series) would make the problem go away, then I'll then chuck the primer bulb and get a new mechanical pump, too.

  

Thanks!



  -- Robert



On Thu, Jul 16, 2009 at 8:22 AM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:

 [quote] Bob, Dump the primer bulb from the system. The last one I had on a plane failed on takeoff. Fortunately I had 2000 ft of runway left and it was a non incident. Thinking I was going to replace it I bought two new ones. One was dead right out of the package and the other is now confined to syphon duty where it can't hurt me.   Rotax used to recommend putting the Facet pump in parallel but has refined that view in light of 20+ years of experience and they're now okay with a series installation. Series installation is just a cleaner installation and I don't believe there's a failure mode of the Facet that can block the fuel system. Unless you have a very long draw the Mikuni pump will do just fine on it's own even with the Facet in the line. I've run mine both ways, Facet on and off, in flight and can't notice any difference.

   



Rick Girard

do not archive



On Thu, Jul 16, 2009 at 6:29 AM, Robert Laird <rlaird(at)cavediver.com (rlaird(at)cavediver.com)> wrote:

  

 [quote]

Hi Carlos!



Thanks for the note.  Actually, the float bowl is probably the first thing I checked, but just forgot to mention it... sorry!  I do like filters after the primer bulb, in case parts of it breaks off, but I thought the mechanical fuel pump had a metal diaphragm?

    

  -- Robert





On Thu, Jul 16, 2009 at 12:17 AM, Carlos <grageda(at)innw.net (grageda(at)innw.net)> wrote:

  

 



[quote]       

 Hi Bob,

  

 You may wish to check the float bowl to see if  there is anything floating around in there. If the pump is failing, there could  be bits of rubber diaphragm getting into the bowl.

  

 It seems now matter how many filters you have, dirt  always seems to get past them.

  

 Hope this helps

  

 BaronVonEvil

 Firestar II

 Rotax 447

 

[quote]   ---

ulflyer(at)verizon.net
Guest

Posted: Thu Jul 16, 2009 10:55 am Post subject: 447 problem

Hi Robert,

Sorry to hear about your problem.



Has the plane & engine been sitting for some period of time?



Is your fuel tank vent open, unobstructed?



What type of fuel filter are you using - what type is it how old is it?

I run the Fram G1 - it's a large clear plastic with a large paper 

element - hard to find in an auto parts - Lockwood sells them - NAPA 

sells a similar filter that looks identical - same molded in fuel 

direction flow marks, just in their own shelf packaging.



Do you have a by-pass on your squeeze bulb - them there peas stick ya know?



How's the fuel pump pulse line (different stuff than regular fuel 

line - thicker wall to keep the pulses strong and not flex and soften 

them), is it solid, flexible, no cracks?



Is your fuel pump mounted below the engine level - if so and it has a 

weep hole, is it positioned toward the lower edge rather than upper 

edge so it can drain out if necessary?  (You can get a build of oil 

in it and can drain out if in the wrong orientation.)



What are your CHT & EGT temps after running for a while at 6200 RPM?



I don't normally run my 447 engine at that high RPM except during 

takeoff and climb out - I normally static with tail tied down at 

5900-6000 RPM, on climb out I will see around 6200 full throttle on 

takeoff climb out.  Sounds like you have experience running this 

engine in this configuration but I'm wondering what EGT's your 

pulling in cruise after you unload the engine (throttle back).  I 

would say your under propped and not loading the engine enough but 

that is another issue unless your EGT's are peaking up there and you 

getting a light seizure - which would draw down the RPM.  If you back 

off the power, give it a short period to cool down, will the RPM pick back up?



THE TIME THAT PASSES BEFORE THE RPM DROPS LEADS ME TO BELIEVE ITS A 

FUEL FLOW PROBLEM.  - GET RID OF THE IN-LINE SQUEEZE BULB or install 

a by-pass around it - take it out, you can pump fuel into the carb 

bowls by turning the prop before startup or use your Facet with a 

check valve on the output tom fill up the fuel bowls.. Keep us posted 

on what you find.

Regards,

jerb



At 08:58 PM 7/15/2009, you wrote:

 	  Quote: 	
		  I've been flying in front of a 912ULS for many years, but am now 

also flying (again) in front of a 447... and I'm already missing the 

reliability!



Ok, so, I'm flying along for 40 minutes, and everything is 

cool.  I'm flying straight-and-level, no throttle changes, just 

cruising, then suddenly the rpms drop 1000rpm, from about 6200 to 

5200, then after a moment, it surges back up to 6200.  Then about 

3-4 seconds later, it does the same thing.  Luckily, I'm near the 

airport, so I make a bee-line to the runway and land safely.



As I land, at the lower throttle settings, it seems okay.  After I 

land, it seems to work fine while I taxi.



I get back to the hangar and let it cool off.  The tank was almost 

dry (had about a gallon left) by that point, so I put in fresh gas 

(always using Mr. Funnel).  After it's cooled off, I try to start 

it, and it starts right up.  It idles normally, then I taxi out and 

try it again.  I circle the airport 3 or 4 times, at around 600-700 

feet, and after 10 minutes the wind starts coming up, so I decide 

I'll cut this test flight short.  Right about then, it starts doing 

it again... I hadn't made any altitude changes, throttle changes, 

and the tank this time was full.  So, it's not bad fuel.



The system pressurizes okay when I use the squeeze bulb and, as I 

said, it starts right up.  No other indications that I can see or 

hear of anything wrong.  I'm going to check the plugs tomorrow, but 

it runs just fine.



My only guess is that maybe the mechanical fuel pump is on it's last 

legs and can't keep the bowl full.  I've got a Facet pump that I 

think I'll plumb in parallel and turn it on throughout a flight, to 

see if that helps.



Anyone else have any ideas what it might be?



   -- Robert

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Thu Jul 16, 2009 11:55 am Post subject: 447 problem

Hey Jerb!  Long time no see, eh?



On Thu, Jul 16, 2009 at 1:54 PM, jerb <ulflyer(at)verizon.net (ulflyer(at)verizon.net)> wrote:

 	  Quote: 	
		   --> Kolb-List message posted by: jerb <ulflyer(at)verizon.net (ulflyer(at)verizon.net)>

 

 Hi Robert,

 Sorry to hear about your problem.

 

 Has the plane & engine been sitting for some period of time? 	


Nope, the engine is run and aircraft flown frequently!  I've recently purchased it, and for the first few hours of flying, it gave me no problems at all.

  

 	  Quote: 	
		   Is your fuel tank vent open, unobstructed? 	


Unobstructed.  

 

 	  Quote: 	
		   What type of fuel filter are you using - what type is it how old is it? 	


It's tiny, and I'll probably replace it since I'm unfamiliar with the type, but I was told it was fairly new.  (I trust the previous owner, BTW.)

  

 	  Quote: 	
		   I run the Fram G1 - it's a large clear plastic with a large paper element - hard to find in an auto parts - Lockwood sells them - NAPA sells a similar filter that looks identical - same molded in fuel direction flow marks, just in their own shelf packaging. 	
 

I prefer non-paper filters, and will probably replace it with something else.  Although I'm not eliminating the filter as the culprit, it's low on my list.

 

 	  Quote: 	
		    Do you have a by-pass on your squeeze bulb - them there peas stick ya know? 	


Yup.  There's a bypass, so if the bulb froze solid-closed, gas would still flow.

 

 	  Quote: 	
		    How's the fuel pump pulse line (different stuff than regular fuel line - thicker wall to keep the pulses strong and not flex and soften them), is it solid, flexible, no cracks? 	


It looks good, but I've ordered a new pulse line and will replace the old one as soon as I can.

  

 	  Quote: 	
		   Is your fuel pump mounted below the engine level - if so and it has a weep hole, is it positioned toward the lower edge rather than upper edge so it can drain out if necessary?  (You can get a build of oil in it and can drain out if in the wrong orientation.) 	
 

It's below the engine; the weep hole is free and clear and I can see a few drops in the right condition, so I know it's open and clear.

 

 	  Quote: 	
		    What are your CHT & EGT temps after running for a while at 6200 RPM? 	


Um, my memory fails me right now, but the red line is marked on both gauges, and the temps have never gone beyond the red line.

  

 	  Quote: 	
		   I don't normally run my 447 engine at that high RPM except during takeoff and climb out - I normally static with tail tied down at 5900-6000 RPM, on climb out I will see around 6200 full throttle on takeoff climb out.  Sounds like you have experience running this engine in this configuration but I'm wondering what EGT's your pulling in cruise after you unload the engine (throttle back).  I would say your under propped and not loading the engine enough but that is another issue unless your EGT's are peaking up there and you getting a light seizure - which would draw down the RPM.  If you back off the power, give it a short period to cool down, will the RPM pick back up? 	
 

The "light seizure" (a really scary term!) is a possibility... Lucien suggested I take a look at the piston, and I'll do that at my first opportunity.  As for giving it a cool down period, I have unfortunately not yet had the opportunity to do extensive testing like that.  I'm hoping for another chance today, if the wind will cooperate.

  

 	  Quote: 	
		   THE TIME THAT PASSES BEFORE THE RPM DROPS LEADS ME TO BELIEVE ITS A FUEL FLOW PROBLEM.  - GET RID OF THE IN-LINE SQUEEZE BULB or install a by-pass around it - take it out, you can pump fuel into the carb bowls by turning the prop before startup or use your Facet with a check valve on the output tom fill up the fuel bowls.. Keep us posted on what you find. 	
 

Yup, I'm thinking along those lines too...  I'll try a Facet and let you know!



Many thanks!



  -- Robert



  [quote][b]

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Thu Jul 16, 2009 6:24 pm Post subject: 447 problem

Well, I did three things tonight, so I don't know if one of them fixed it, if it's really fixed or if one did, which one!



I put a couple of tiny holes in the gas cap, to be 100% sure it's vented.



 Then I removed the primer bulb completely.

 

Then I installed a Facet pump.



I went and flew about 10-15 minutes... it was almost dark when I touched down... and no repeat of the problem.  But, the other day, it took 40 minutes before it showed up, so I'm not sure at all that I've solved the problem.



Thanks for everyone's suggestions... I'll let you know in a week or so if the problem stays gone!



  -- RObert

  [quote][b]

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

dalewhelan

Joined: 11 Nov 2008
Posts: 105
Location: USA ARIZONA fountain hills

Posted: Wed Aug 12, 2009 5:56 pm Post subject: Re: 447 problem

has this problem been solved yet?

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Dale Whelan
503 powered Firestar II, Luscombe 8A
Projection, A simple and interesting Psychological concept

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Thu Aug 13, 2009 7:30 am Post subject: Re: 447 problem

 	  rlaird wrote: 	
		  

 

Then I installed a Facet pump.



Thanks for everyone's suggestions... I'll let you know in a week or so if the problem stays gone!



ï¿½ -- RObert



	




That Facet pump is the best thing you could have possibly done.  The little pulse pump that is standard for the 447  is barely up to the job of keeping fuel to the engine.  The first time there is the slightest degradation of performance of the pulse pump, or slightest restriction in filter, or fuel system in any way the engine will be starved of fuel.  It is crazy to depend on such a marginal pump to keep your engine running when the Facet pump is so cheap, easy to install, and reduces your chance of an engine failure by a considerable amount.  It is even worse to screw around with squeeze bulbs that frequently break and can block the fuel system when a very reliable facet pump can easily take its place for priming, and serves as a really good backup in flight also.  The Facet pump has enough capacity to keep enough fuel flow to the engine even if something else is not quite perfect.    



The other thing I would do is buy a really good fuel filter like this 10 micron stainless steel filter from Aircraft Spruce.



http://www.aircraftspruce.com/catalog/appages/micron10.php



This filter is designed to be cleaned and will last forever.  At 10 microns, it will far outperform any paper or disposable filter out there.  This filter has two screens inside, a coarse trapping larger debris and keeping the the 10 micron screen from clogging.  The filter screen has a large amount of surface area and it would take a lot of abuse and neglect to cause a flow restriction in this filter, in other words,  with this filter your fuel system will stay clean long after the cheap filters most people use have failed.  Over time, this filter pays for itself, because you just clean it instead of replacing it.



Doing these two items can save you many headaches and will very probably save a forced landing one day.   According to EAA, half of all engine failures in experimental airplanes are caused by the fuel system, doing these two things goes a long ways towards improving your odds.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

Ralph B

Joined: 14 Apr 2007
Posts: 367
Location: Mound Minnesota

Posted: Thu Aug 13, 2009 8:04 am Post subject: Re: 447 problem

I had a similar problem a few years back on my 447. I landed and took off the float bowl. It was a small piece of grass at the bottom. I dumped it and took off without any problems after that. How did the grass get in there? Occasionally I take off the bowl to see what it looks like on the inside. Since I fly from a grass strip, a piece of grass must have been in back, on the outside, that I didn't see and got in. Now, I wipe down the outside of the bowl before taking it off.



Ralph B

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Ralph B

Kolb Kolbra 912uls
N20386
550 hours

Arksey(at)aol.com
Guest

Posted: Thu Aug 13, 2009 9:14 am Post subject: 447 problem

In a message dated 8/13/2009 11:31:53 A.M. Eastern Daylight Time,  orcabonita(at)hotmail.com writes:

  	  Quote: 	
		  

rlaird wrote:

 	  Quote: 	
		   

  

 Then I installed a    Facet pump.

 

 Thanks for everyone's suggestions... I'll let you    know in a week or so if the problem stays gone!

 

 ï¿½ --    RObert

 

 


	




That Facet pump is the best thing you    could have possibly done.  The little pulse pump that is standard for the    447  is barely up to the job of keeping fuel to the engine.  The    first time there is the slightest degradation of performance of the pulse    pump, or slightest restriction in filter, or fuel system in any way the engine    will be starved of fuel.  It is crazy to depend on such a marginal pump    to keep your engine running when the Facet pump is so cheap, easy to install,    and reduces your chance of an engine failure by a considerable amount.     It is even worse to screw around with squeeze bulbs that frequently break and    can block the fuel system when a very reliable facet pump can easily take its    place for priming, and serves as a really good backup in flight also.     The Facet pump has enough capacity to keep enough fuel flow to the engine even    if something else is not quite perfect.    



The other thing I    would do is buy a really good fuel filter like this 10 micron stainless steel    filter from Aircraft    Spruce.



http://www.aircraftspruce.com/catalog/appages/micron10.php



This    filter is designed to be cleaned and will last forever.  At 10 microns,    it will far outperform any paper or disposable filter out there.  This    filter has two screens inside, a coarse trapping larger debris and keeping the    the 10 micron screen from clogging.  The filter screen has a large amount    of surface area and it would take a lot of abuse and neglect to cause a flow    restriction in this filter, in other words,  with this filter your fuel    system will stay clean long after the cheap filters most people use have    failed.  Over time, this filter pays for itself, because you just clean    it instead of replacing it.



Doing these two items can save you many    headaches and will very probably save a forced landing one day.      According to EAA, half of all engine failures in experimental airplanes are    caused by the fuel system, doing these two things goes a long ways towards    improving your odds.



Mike



--------

&quot;NO    FEAR&quot; -  If you have no fear you did not go as fast as you could    have !!!



Kolb MK-III Xtra, 912-S 	


 

Well said Mike, I agree with what you said, I had a fuel  problem with my 503 prior to changing fuel system and using a facet  pump....

  

 do not archive

 JIM  SWAN

firestar ll, 503, N663S

Eaton Rapids, Mi. 48827

PH 517-663-8488  runway 2300' E & W (42-28.58N 084-44.69 W  )

 

  [quote][b]

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Aug 13, 2009 9:58 am Post subject: Re: 447 problem

 	  JetPilot wrote: 	
		  

That Facet pump is the best thing you could have possibly done.  The little pulse pump that is standard for the 447  is barely up to the job of keeping fuel to the engine.  The first time there is the slightest degradation of performance of the pulse pump, or slightest restriction in filter, or fuel system in any way the engine will be starved of fuel.  It is crazy to depend on such a marginal pump to keep your engine running when the Facet pump is so cheap, easy to install, and reduces your chance of an engine failure by a considerable amount.  It is even worse to screw around with squeeze bulbs that frequently break and can block the fuel system when a very reliable facet pump can easily take its place for priming, and serves as a really good backup in flight also.  The Facet pump has enough capacity to keep enough fuel flow to the engine even if something else is not quite perfect.    



The other thing I would do is buy a really good fuel filter like this 10 micron stainless steel filter from Aircraft Spruce.



http://www.aircraftspruce.com/catalog/appages/micron10.php



This filter is designed to be cleaned and will last forever.  At 10 microns, it will far outperform any paper or disposable filter out there.  This filter has two screens inside, a coarse trapping larger debris and keeping the the 10 micron screen from clogging.  The filter screen has a large amount of surface area and it would take a lot of abuse and neglect to cause a flow restriction in this filter, in other words,  with this filter your fuel system will stay clean long after the cheap filters most people use have failed.  Over time, this filter pays for itself, because you just clean it instead of replacing it.



Doing these two items can save you many headaches and will very probably save a forced landing one day.   According to EAA, half of all engine failures in experimental airplanes are caused by the fuel system, doing these two things goes a long ways towards improving your odds.



Mike 	




A couple of nits real quick....



The mikuni pneumatic pumps actually offer very good fuel draw, even in cases like the Kolb with the tank well below the engine. 



They tend to get a bad rap because of certain installation errors:



- incorrect pulse line length. Far and away this is the most common (and dangerous) error - I've seen all kinds of mile-long pulse lines accomodating incorrect installation methods by various manufacturers. Often there's not a very pretty place to put the pump so that it's near enough to the engine to allow a short pulse line. Sometimes it's simply not known that the line has to be a foot or less regardless of what material is used. Too long of a pulse line dangerously weakens the action of the pump.



- putting drag-inducing stuff in the vacuum side of the line like fuel bulbs and, yes, electric pumps . The facet pump does introduce significant drag on the fuel when it's turned off (should be installed on the pressure side of the pneumatic if you must have an electric pump). The squeeze bulbs do as well, tho not quite as bad as the electric pumps. 



It's generally best to eliminate both, so you have a fully freely flowing fuel line on both ends of the pneumatic. 



I've run the mikuni pneumatics for about a decade and never had a moment's trouble with fuel draw, even on my FSII with the tank a long ways below the carburettors. But the installation has to be correct to avoid trouble.



LS

_________________
LS
Titan II SS

Ralph B

Joined: 14 Apr 2007
Posts: 367
Location: Mound Minnesota

Posted: Thu Aug 13, 2009 2:04 pm Post subject: Re: 447 problem

I've flown with the Mikuni pumps for 22 years and the only problem I've seen was when I replaced the diaphragm with one that was an aftermarket part that wasn't like the original. It ran rough and I replaced the pump. I found it had been creased and was leaking fuel out the weep hole.



If you think the single Mikuni pump is marginal, then use a dual Mikuni and tie the outputs together. This is what I have on my 447.



Never use fuel line for the pulse line. I use single-walled auto fuel line. It's very rigid and won't collapse. Some guys use pneumatic line, which is good too.



Ralph B

_________________
Ralph B

Kolb Kolbra 912uls
N20386
550 hours

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