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AC-680 FLP Engine RPM Fluctuation
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hcourier(at)cox.net
Guest

Posted: Sun Oct 26, 2008 5:17 pm Post subject: AC-680 FLP Engine RPM Fluctuation

Am having a problem with the left engine on the 680 FLP I fly (Mr. RPM Conversion).  Takeoff is fine but on climb out the left engine RPM is unsteady,  somewhat like a prop that won't stabilize.  Here's some info:



1.  The problem seems to occur primarily during climb as I bring the    

      turbos up (I've got manual turbos)

2.  The fluctuation is random as to when it occurs and how much the RPM

      fluctuates...probably 10-20 RPM.  Sometimes it's noticeable as the

      aircraft yaws, sometimes it's not noticeable.

3.  Sometimes it  seems that leaning the mixture helps a bit but not 

      always

4.  I've also noticed that sometimes when the problem has occured on a

      flight that on shutdown of the engine after landing, it doesn't want to 

      stop running with the mixture pulled all the way to lean/idle-cutoff.  

5.  Sometimes I the lean the mixture during the 1500 RPM ground check

      and the RPM goes up 50 RPM or so, sometimes it doesn't

6.  Once I level off the problem seems to disappear or be almost 

      un-noticeable. Although tonight I applied full rich mixture while in level

      flight at 4,500' and I could notice a slight RPM fluctuation if I paid close

      attention.

7.  Fuel pressure is normal and turning the fuel pump on or off has no

      affect on the engine



My thoughts:



1.  I think the problem is in some fuel metering mechanism in the

      carburetor that is unsteady  

2.  At one point I thought there might be a leak in the turbo pressure

     lines causing a fluctuation in turbo air to the engine

3.  Now, with the engine shut down problem (doesn't happen every time)

      I think there is a link between the turbo air (as I bring it up on climb)

      and fuel metering.  They are probably interrelated.



I've received help from many of you out there before.  Has anyone had this type problem occur and if so what might be the problem?



Thank you,



Ray Mansfield

N91ES

850-217-5185

cschuerm(at)cox.net
Guest

Posted: Sun Oct 26, 2008 6:03 pm Post subject: AC-680 FLP Engine RPM Fluctuation

Ray Mansfeld wrote:

 	  Quote: 	
		   I've received help from many of you out there before.  Has anyone had this type problem occur and if so what might be the problem?


	


Do you have a multi-channel EGT/CHT system?  If so, what are the EGT's 

doing when this occurs.

There are several possible problems which could cause this, but it does 

sound like you're looking in the right area.  Have you carefully 

inspected the upper deck reference lines?  That would be my first guess 

before digging into the injection body.  I think those were all hand 

fabricated by mrrpm since a normal io-720 wouldn't have them.  Look for 

a cracked line at the solder joint on the injector.



chris

tfisher(at)commandergroup
Guest

Posted: Mon Oct 27, 2008 6:35 am Post subject: AC-680 FLP Engine RPM Fluctuation

I had the same surging problem on mine.

I replaced all the upper deck lines with new stainless steel lines, the new 

lines also had to be welded in two places, this resolved the surging 

problem.

Tom

C-GISS

680FLP (Mr.RPM)

---

drwer2

Joined: 24 Sep 2008
Posts: 41
Location: Squaw Valley, CA

Posted: Mon Oct 27, 2008 7:00 am Post subject: AC-680 FLP Engine RPM Fluctuation

Tom, did 



--- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca> wrote:

 [quote]From: Tom Fisher <tfisher(at)commandergroup.bc.ca>

Subject: Re: AC-680 FLP Engine RPM Fluctuation

To: commander-list(at)matronics.com

Date: Monday, October 27, 2008, 7:34 AM



[quote]--> Commander-List message posted by: "Tom Fisher" <tfisher(at)commandergroup.bc.ca>  I had the same surging problem on mine. I replaced all the upper deck lines with new stainless steel lines, the new  lines also had to be welded in two places, this resolved the surging  problem. Tom C-GISS 680FLP (Mr.RPM) ---

_________________
No Generality is worth a damn....including this one.

cogito ergo aero-geek

drwer2

Joined: 24 Sep 2008
Posts: 41
Location: Squaw Valley, CA

Posted: Mon Oct 27, 2008 7:00 am Post subject: AC-680 FLP Engine RPM Fluctuation

Tom, 



--- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca> wrote:

 [quote]From: Tom Fisher <tfisher(at)commandergroup.bc.ca>

Subject: Re: AC-680 FLP Engine RPM Fluctuation

To: commander-list(at)matronics.com

Date: Monday, October 27, 2008, 7:34 AM



[quote]--> Commander-List message posted by: "Tom Fisher" <tfisher(at)commandergroup.bc.ca>  I had the same surging problem on mine. I replaced all the upper deck lines with new stainless steel lines, the new  lines also had to be welded in two places, this resolved the surging  problem. Tom C-GISS 680FLP (Mr.RPM) ---

_________________
No Generality is worth a damn....including this one.

cogito ergo aero-geek

drwer2

Joined: 24 Sep 2008
Posts: 41
Location: Squaw Valley, CA

Posted: Mon Oct 27, 2008 7:05 am Post subject: AC-680 FLP Engine RPM Fluctuation

Tom, did you replace the lines with ones of the same Inside diameter?  Did you replace those on both sides of the flow divider (spider), and the fuel servo?

 

wer



--- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca> wrote:



From: Tom Fisher <tfisher(at)commandergroup.bc.ca>

Subject: Re: AC-680 FLP Engine RPM Fluctuation

To: commander-list(at)matronics.com

Date: Monday, October 27, 2008, 7:34 AM




<tfisher(at)commandergroup.bc.ca>



I had the same surging problem on mine.

I replaced all the upper deck lines with new stainless steel lines, the new 

lines also had to be welded in two places, this resolved the surging 

problem.

Tom

C-GISS

680FLP (Mr.RPM)

---

_________________
No Generality is worth a damn....including this one.

cogito ergo aero-geek

tfisher(at)commandergroup
Guest

Posted: Mon Oct 27, 2008 9:59 am Post subject: AC-680 FLP Engine RPM Fluctuation

I got a new set from Mr.RPM himself so I assume they were  of the same inside diameter and yes his lines leaked and had to be welded in two  places. I just replaced the lines from the flow divider to the  cylinders.

 Tom.

 C-GISS

  

 [quote]   ---

drwer2

Joined: 24 Sep 2008
Posts: 41
Location: Squaw Valley, CA

Posted: Mon Oct 27, 2008 10:56 am Post subject: AC-680 FLP Engine RPM Fluctuation

Thanks Tom.

 

Ive designed a few fuel systems and his symptoms are typical of a flowdivider/lines on the hot side of an engine. (side downstream of an air cooled engine) And are more prevalent with Lines that have a lot of volume.  

 

Im unfamiliar with Commanders, but from the looks of the cowl inlets on some of them, it appears the cooling airflow is from bottom to top and then out.  If not then there is a big air-dam that deflects cool air to the top of the engine and then down.  Either way, cooling appears greatly reduced during climbout unless there are some big cown-vents downstream.

 

As Ive seen it.

1.  larger dia. lines have a higher vapor/liquid ratio during operation, and on shut down, cook-off the remaining fuel in the FDV.  they are better, however on climbout as there is less pressure losses and heat absorbed.  Modern FDV's have a purge valve that dumps fuel back to the inlet of the pump on shutdown.  this immediately drops the pressure at the nozzles to zero...

 

2. smaller lines have shorter fill times, quicker starts but are susceptible to vapor lock because they absorb heat faster.  At higher flowrates (rich) the delta-P loss in these lines may result in a higher vapor/liquid rato  and thus a poorer spray patter at the nozzle.  This is more of an issue on climbout on engines with poor cooling for whatever reason (like closed cowlvents, or just reduced airspeed (airflow)).  Modern fuellines in these situations are insulated (just like grandpas truck).

 

3.  for systems with high flowrates (~100 pph or more) the different lengths of fuel lines from the FDV to each nozzle becomes important.  there are different pressure losses in each leg. (which makes GAMI's all the more important. )  If you want to save yourself the recurring cost of Gami injectors...get your flow divider valve balanced with your set of nozzles.

 

Just some thoughts.

 

wer

former Pratt-Whitney and Ham-STD

 

 



--- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca> wrote:



From: Tom Fisher <tfisher(at)commandergroup.bc.ca>

Subject: Re: AC-680 FLP Engine RPM Fluctuation

To: commander-list(at)matronics.com

Date: Monday, October 27, 2008, 10:57 AM



I got a new set from Mr.RPM himself so I assume they were of the same inside diameter and yes his lines leaked and had to be welded in two places. I just replaced the lines from the flow divider to the cylinders.

Tom.

C-GISS

 



---

_________________
No Generality is worth a damn....including this one.

cogito ergo aero-geek

tfisher(at)commandergroup
Guest

Posted: Mon Oct 27, 2008 1:19 pm Post subject: AC-680 FLP Engine RPM Fluctuation

Well, I am that much more informed, thanks for the  info.

 Tom

 C-GISS

 [quote]   ---

drwer2

Joined: 24 Sep 2008
Posts: 41
Location: Squaw Valley, CA

Posted: Tue Oct 28, 2008 7:14 am Post subject: AC-680 FLP Engine RPM Fluctuation

Well, Next time you fly, once youve leaned for cruise, check the EGTs for those cylilnders that had the new lines welded.  If they are running within a few degrees of the others, then he did a good job welding.  SS lines with anything less than 130 thou. diam are extremely hard to weld without causing an "orifice" at the weldsite. 

 

 Also, I doubt that he annealed the new weld, which will make the heat affected zone more brittle than the rest. Ask him how he treated the weld.  (a smoky acetylene torch for  2 minutes would be sufficient.

 

Bottom line, Mr.RPM should have is axxx chewed for sending you lousy parts. You shouldnt have to do his Acceptance test procedures on your AC.

 

wer



--- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca> wrote:



From: Tom Fisher <tfisher(at)commandergroup.bc.ca>

Subject: Re: AC-680 FLP Engine RPM Fluctuation

To: commander-list(at)matronics.com

Date: Monday, October 27, 2008, 2:17 PM



Well, I am that much more informed, thanks for the info.

Tom

C-GISS



---

_________________
No Generality is worth a damn....including this one.

cogito ergo aero-geek

tfisher(at)commandergroup
Guest

Posted: Tue Oct 28, 2008 7:48 pm Post subject: AC-680 FLP Engine RPM Fluctuation

I do not yet have engine monitors but they are on the wish  list.

  

 Well he was out of the business and already sold the STC  and as far as I was concerned I was happy to receive the  lines from him even if they had to be tweaked by an expensive AME who did in  fact anneal the welds, good point.

 Tom.

 C-GISS

 [quote]   ---

don.barry(at)sbcglobal.ne
Guest

Posted: Tue Oct 28, 2008 8:05 pm Post subject: AC-680 FLP Engine RPM Fluctuation

MR. RPM is out of business?? I wonder whatever happened to that AC they were playing around with the water-cooled Orenda engines…   

   

Don  

Houston TX  

         

  

From: owner-commander-list-server(at)matronics.com [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Tom Fisher

 Sent: Tuesday, October 28, 2008 10:46 PM

 To: commander-list(at)matronics.com

 Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation  

  

     

I do not yet have engine monitors but they are on the wish list.  

    

   

    

Well he was out of the business and already sold the STC and as far as I was concerned I was happy to receive the lines from him even if they had to be tweaked by an expensive AME who did in fact anneal the welds, good point.  

    

Tom.  

    

C-GISS  

  [quote]    

---

nico(at)cybersuperstore.c
Guest

Posted: Tue Oct 28, 2008 9:26 pm Post subject: AC-680 FLP Engine RPM Fluctuation

I am not sure that I remember the Orenda story correctly,  Don, but folks on this list know a lot more about it than I do. Apparently it  ran out of money and / or there wasn't enough push in Canada at the time to  complete the job to certification. Perhaps someone could enlighten us, but it is  a topic that has been discussed until there was a grove in the ground.  

 Nico

  



   From: owner-commander-list-server(at)matronics.com  [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Don Barry  Home

Sent: Tuesday, October 28, 2008 9:00 PM

To:  commander-list(at)matronics.com

Subject: RE: AC-680 FLP  Engine RPM Fluctuation

 

  

MR. RPM is out of  business?? I wonder whatever happened to that AC they were playing around with  the water-cooled Orenda engines…  

  

Don 

Houston TX 

     

 

From:  owner-commander-list-server(at)matronics.com  [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Tom Fisher

Sent: Tuesday, October 28, 2008 10:46  PM

To: commander-list(at)matronics.com

Subject: Re: AC-680 FLP  Engine RPM Fluctuation

 

   

I do not yet have engine monitors  but they are on the wish list.

  

 

  

Well he was out of the business and  already sold the STC and as far as I was concerned I was happy to receive the  lines from him even if they had to be tweaked by an expensive AME who did in  fact anneal the welds, good point.

  

Tom.

  

C-GISS

 [quote]      

---

craigk391(at)sbcglobal.ne
Guest

Posted: Tue Oct 28, 2008 11:07 pm Post subject: AC-680 FLP Engine RPM Fluctuation

The STC's were picked up by a guy in FL. The link still workscraig 

Sent via BlackBerry by AT&T

From:  "Don Barry Home" <don.barry(at)sbcglobal.net>

Date: Tue, 28 Oct 2008 23:00:26 -0500

To: <commander-list(at)matronics.com>

Subject: RE: Commander-List: AC-680 FLP Engine RPM Fluctuation

MR. RPM is out of business?? I = wonder whatever happened to that AC they were playing around with the = water-cooled Orenda engines…  

Don 

Houston TX 

From: owner-commander-list-server(at)matronics.com [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Tom Fisher

Sent: Tuesday, October = 28, 2008 10:46 PM

To: commander-list(at)matronics.com

Subject: Re: = Commander-List: AC-680 FLP Engine RPM Fluctuation 

I do not yet have engine monitors but they are on the = wish list. 

Well he was out of the business and already sold the = STC and as far as I was concerned I was happy to receive the lines from him even = if they had to be tweaked by an expensive AME who did in fact anneal the = welds, good point. 

Tom. 

C-GISS 

 [quote]=   

---

Peter Bichier

Joined: 25 Aug 2008
Posts: 103
Location: Toledo, Ohio

Posted: Wed Oct 29, 2008 1:32 am Post subject: AC-680 FLP Engine RPM Fluctuation

Dick MacCoon's old site is still available (actually the domain is for sale)

http://www.mrrpm.com/



it still has a video on the "promissing" (2002) new aluminum V8 water cooled engines which were supposed to be cheaper and fuel efficient...



RPM Commander LLC is still in business and selling a couple of 560Fs

http://www.rpmcommander.com/



To reach: RPM COMMANDER LLC (For STC services)

c/o Paul Gendron 

1401 N. Riverside Drive Suite 607 

Pompano Beach, FLorida, USA 33062

_________________
560 Dreamer

rsrandazzo(at)precisionma
Guest

Posted: Wed Oct 29, 2008 5:20 am Post subject: AC-680 FLP Engine RPM Fluctuation

Don-  

   

The engine technology was picked up by an outfit called Trace Engines.  (www.traceengines.com)  

   

They had a stand set up at the races this year at Reno.  We stopped by to chat with them- and they brought around a fellow who has purchased the original Orenda certification test airplane.  He has a second outfit that he explained was working to STC the 685 with these engines mounted.  He claimed that they were “months away from an STC” to hang the V8s on 685s….  

   

That Mr. RPM test bed commander is currently on the ground in Midland TX and according to some sources I checked with- it hasn’t  been flying in some time..  

   

Like all things in GA- seems to be more heat than energy being generated on that project.    

   

Robert S. Randazzo  

N414C  

   

       

From: owner-commander-list-server(at)matronics.com [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Don Barry Home

 Sent: Tuesday, October 28, 2008 9:00 PM

 To: commander-list(at)matronics.com

 Subject: RE: AC-680 FLP Engine RPM Fluctuation  

  

  

   

MR. RPM is out of business?? I wonder whatever happened to that AC they were playing around with the water-cooled Orenda engines…   

   

Don  

Houston TX  

         

  

From: owner-commander-list-server(at)matronics.com [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Tom Fisher

 Sent: Tuesday, October 28, 2008 10:46 PM

 To: commander-list(at)matronics.com

 Subject: Re: AC-680 FLP Engine RPM Fluctuation  

  

     

I do not yet have engine monitors but they are on the wish list.  

    

   

    

Well he was out of the business and already sold the STC and as far as I was concerned I was happy to receive the lines from him even if they had to be tweaked by an expensive AME who did in fact anneal the welds, good point.  

    

Tom.  

    

C-GISS  

  [quote]    

----- Original Message -----   

    

From: willis robison (drwer2(at)yahoo.com)   

    

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

    

Sent: Tuesday, October 28, 2008 8:11 AM  

    

Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation  

    

   

             

Well, Next time you fly, once youve leaned for cruise,   check the EGTs for those cylilnders that had the new lines welded.  If   they are running within a few degrees of the others, then he did a good job   welding.  SS lines with anything less than 130 thou. diam are   extremely hard to weld without causing an "orifice" at the   weldsite.    

      

    

      

 Also, I doubt that he annealed the new weld,   which will make the heat affected zone more brittle than the rest. Ask   him how he treated the weld.  (a smoky acetylene torch for  2   minutes would be sufficient.   

      

    

      

Bottom line, Mr.RPM should have is axxx chewed for sending   you lousy parts. You shouldnt have to do his Acceptance test procedures on   your AC.   

      

    

      

wer

   

   --- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca>   wrote:   

   [quote]   

From: Tom Fisher   <tfisher(at)commandergroup.bc.ca>

   Subject: Re: AC-680 FLP Engine RPM Fluctuation

   To: commander-list(at)matronics.com

   Date: Monday, October 27, 2008, 2:17 PM         

Well, I am   that much more informed, thanks for the info.   

      

Tom   

      

C-GISS   

   [quote]      

-----   Original Message -----    

      

From: willis robison (drwer2(at)yahoo.com)    

      

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

      

Sent: Monday, October   27, 2008 11:54 AM   

      

Subject: Re:   AC-680 FLP Engine RPM Fluctuation   

      

    

                      

Thanks Tom.     

          

      

          

Ive designed a few fuel systems and his symptoms are     typical of a flowdivider/lines on the hot side of an engine. (side     downstream of an air cooled engine) And are more prevalent     with Lines that have a lot of volume.       

          

      

          

Im unfamiliar with Commanders, but from the looks of the     cowl inlets on some of them, it appears the cooling airflow is from     bottom to top and then out.  If not then there is a big air-dam that     deflects cool air to the top of the engine and then down.  Either way,     cooling appears greatly reduced during climbout unless there are some big cown-vents     downstream.     

          

      

          

As Ive seen it.     

          

1.  larger dia. lines have a higher vapor/liquid     ratio during operation, and on shut down, cook-off the remaining fuel     in the FDV.  they are better, however on climbout as there is less     pressure losses and heat absorbed.  Modern FDV's have a purge valve     that dumps fuel back to the inlet of the pump on shutdown.  this     immediately drops the pressure at the nozzles to zero...     

          

      

          

2. smaller lines have shorter fill times, quicker starts     but are susceptible to vapor lock because they absorb heat faster.  At     higher flowrates (rich) the delta-P loss in these lines may result in a     higher vapor/liquid rato  and thus a poorer spray patter at the     nozzle.  This is more of an issue on climbout on engines with poor cooling     for whatever reason (like closed cowlvents, or just reduced airspeed     (airflow)).  Modern fuellines in these situations are insulated (just     like grandpas truck).     

          

      

          

3.  for systems with high flowrates (~100 pph or     more) the different lengths of fuel lines from the FDV to each nozzle     becomes important.  there are different pressure losses in each leg.     (which makes GAMI's all the more important. )  If you want to     save yourself the recurring cost of Gami injectors...get your flow divider     valve balanced with your set of nozzles.     

          

      

          

Just some thoughts.     

          

      

          

wer     

          

former Pratt-Whitney and Ham-STD     

          

      

          

      

          



     --- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca>     wrote:     

     [quote]     

From: Tom Fisher     <tfisher(at)commandergroup.bc.ca>

     Subject: Re: AC-680 FLP Engine RPM Fluctuation

     To: commander-list(at)matronics.com

     Date: Monday, October 27, 2008, 10:57 AM               

I got a     new set from Mr.RPM himself so I assume they were of the same inside     diameter and yes his lines leaked and had to be welded in two places. I     just replaced the lines from the flow divider to the cylinders.     

          

Tom.     

          

C-GISS     

          

      

     [quote]          

-----     Original Message -----      

          

From: willis     robison (drwer2(at)yahoo.com)      

          

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

          

Sent: Monday, October     27, 2008 7:59 AM     

          

Subject: Re:     AC-680 FLP Engine RPM Fluctuation     

          

      

                                

Tom, did you replace the lines with ones of the same       Inside diameter?  Did you replace those on both sides of the flow       divider (spider), and the fuel servo?       

              

        

              

wer

       

       --- On Mon, 10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca (tfisher(at)commandergroup.bc.ca)>       wrote:       

       [quote]       

From: Tom Fisher <tfisher(at)commandergroup.bc.ca (tfisher(at)commandergroup.bc.ca)>

       Subject: Re: AC-680 FLP Engine RPM Fluctuation

       To: commander-list(at)matronics.com

       Date: Monday, October 27, 2008, 7:34 AM       [quote]--> Commander-List message posted by: "Tom Fisher"<tfisher(at)commandergroup.bc.ca> I had the same surging problem on mine.I replaced all the upper deck lines with new stainless steel lines, the new lines also had to be welded in two places, this resolved the surging problem.TomC-GISS680FLP (Mr.RPM)---

nico(at)cybersuperstore.c
Guest

Posted: Wed Oct 29, 2008 6:48 am Post subject: AC-680 FLP Engine RPM Fluctuation

Well I do hope that they get some traction with this. Adams  shutting down, Eclipse not going anywhere fast, are all bad news for GA. A  success story would be a nice change. I, for one, would be very hesitant to load  up a 685 with family and launch them with Orendas into the night over the  Rockies but their STC with the ag planes do show that it can be a reliable  powerplant. Having a couple of successful races under their belt can do  wonders.

  

  



   From: owner-commander-list-server(at)matronics.com  [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Robert S.  Randazzo

Sent: Wednesday, October 29, 2008 6:18 AM

To:  commander-list(at)matronics.com

Subject: RE: AC-680 FLP  Engine RPM Fluctuation

 

  

Don- 

  

The  engine technology was picked up by an outfit called Trace Engines.  (www.traceengines.com) 

  

They  had a stand set up at the races this year at Reno.  We stopped by to chat  with them- and they brought around a fellow who has purchased the original  Orenda certification test airplane.  He has a second outfit that he  explained was working to STC the 685 with these engines mounted.  He  claimed that they were “months away from an STC” to hang the V8s on  685s…. 

  

That  Mr. RPM test bed commander is currently on the ground in Midland TX and  according to some sources I checked with- it hasn’t  been flying in some  time.. 

  

Like  all things in GA- seems to be more heat than energy being generated on that  project.   

  

Robert  S. Randazzo 

N414C 

  

    

From:  owner-commander-list-server(at)matronics.com  [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Don Barry  Home

Sent: Tuesday, October 28, 2008 9:00 PM

To:  commander-list(at)matronics.com

Subject: RE: AC-680 FLP  Engine RPM Fluctuation



 

  

MR. RPM  is out of business?? I wonder whatever happened to that AC they were playing  around with the water-cooled Orenda engines…  

  

Don 

Houston  TX 

     

 

From:  owner-commander-list-server(at)matronics.com  [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Tom  Fisher

Sent: Tuesday, October 28, 2008 10:46 PM

To:  commander-list(at)matronics.com

Subject: Re: AC-680 FLP  Engine RPM Fluctuation

 

   

I do not yet  have engine monitors but they are on the wish list.

  

 

  

Well he was  out of the business and already sold the STC and as far as I was concerned I was  happy to receive the lines from him even if they had to be tweaked by an  expensive AME who did in fact anneal the welds, good  point.

  

Tom.

  

C-GISS

 [quote]      

----- Original    Message ----- 

      

From: willis robison (drwer2(at)yahoo.com)    

      

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

      

Sent: Tuesday, October    28, 2008 8:11 AM

      

Subject: Re:    AC-680 FLP Engine RPM Fluctuation

      

 

                                      

Well, Next time you fly, once youve leaned for          cruise, check the EGTs for those cylilnders that had the new lines          welded.  If they are running within a few degrees of the others,          then he did a good job welding.  SS lines with anything less than          130 thou. diam are extremely hard to weld without causing an          "orifice" at the weldsite. 

                  

 

                  

 Also, I doubt that he annealed the new          weld, which will make the heat affected zone more brittle than the          rest. Ask him how he treated the weld.  (a smoky acetylene torch          for  2 minutes would be sufficient.

                  

 

                  

Bottom line, Mr.RPM should have is axxx chewed for          sending you lousy parts. You shouldnt have to do his Acceptance test          procedures on your AC.

                  

 

                  

wer



--- On Mon, 10/27/08, Tom Fisher          <tfisher(at)commandergroup.bc.ca>          wrote:

         [quote]           

From: Tom Fisher            <tfisher(at)commandergroup.bc.ca>

Subject: Re: Commander-List:            AC-680 FLP Engine RPM Fluctuation

To:            commander-list(at)matronics.com

Date: Monday, October 27, 2008, 2:17            PM                                 

Well, I am that much more            informed, thanks for the info.

                      

Tom

                      

C-GISS

           [quote]                          

-----              Original Message ----- 

                          

From: willis robison (drwer2(at)yahoo.com) 

                          

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

                          

Sent: Monday,              October 27, 2008 11:54 AM

                          

Subject: Re:              AC-680 FLP Engine RPM              Fluctuation

                          

 

                                                                                                  

Thanks Tom.

                                      

 

                                      

Ive designed a few fuel systems and his                    symptoms are typical of a flowdivider/lines on the hot side of                    an engine. (side downstream of an air cooled                    engine) And are more prevalent with Lines that                    have a lot of volume.  

                                      

 

                                      

Im unfamiliar with Commanders, but from the                    looks of the cowl inlets on some of them, it appears the                    cooling airflow is from bottom to top and then out.  If                    not then there is a big air-dam that deflects cool air to the                    top of the engine and then down.  Either way, cooling                    appears greatly reduced during climbout unless there are some                    big cown-vents downstream.

                                      

 

                                      

As Ive seen it.

                                      

1.  larger dia. lines have a higher                    vapor/liquid ratio during operation, and on shut down,                    cook-off the remaining fuel in the FDV.  they are better,                    however on climbout as there is less pressure losses and heat                    absorbed.  Modern FDV's have a purge valve that dumps                    fuel back to the inlet of the pump on shutdown.  this                    immediately drops the pressure at the nozzles to                    zero...

                                      

 

                                      

2. smaller lines have shorter fill times,                    quicker starts but are susceptible to vapor lock because they                    absorb heat faster.  At higher flowrates (rich) the                    delta-P loss in these lines may result in a higher                    vapor/liquid rato  and thus a poorer spray patter at the                    nozzle.  This is more of an issue on climbout on engines                    with poor cooling for whatever reason (like closed cowlvents,                    or just reduced airspeed (airflow)).  Modern fuellines in                    these situations are insulated (just like grandpas                    truck).

                                      

 

                                      

3.  for systems with high flowrates                    (~100 pph or more) the different lengths of fuel lines from                    the FDV to each nozzle becomes important.  there are                    different pressure losses in each leg. (which makes GAMI's all                    the more important. )  If you want to save yourself                    the recurring cost of Gami injectors...get your flow divider                    valve balanced with your set of nozzles.

                                      

 

                                      

Just some thoughts.

                                      

 

                                      

wer

                                      

former Pratt-Whitney and                    Ham-STD

                                      

 

                                      

 

                                      



--- On Mon, 10/27/08, Tom Fisher                    <tfisher(at)commandergroup.bc.ca>                    wrote:

                   [quote]                     

From: Tom                      Fisher <tfisher(at)commandergroup.bc.ca>

Subject: Re:                      AC-680 FLP Engine RPM Fluctuation

To:                      commander-list(at)matronics.com

Date: Monday, October 27,                      2008, 10:57 AM                                                               

I got a new set                      from Mr.RPM himself so I assume they were of the same inside                      diameter and yes his lines leaked and had to be welded in                      two places. I just replaced the lines from the flow divider                      to the cylinders.

                                          

Tom.

                                          

C-GISS

                                          

 

                     [quote]                                              

-----                        Original Message ----- 

                                              

From:                        willis robison (drwer2(at)yahoo.com)                        

                                              

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

                                              

Sent:                        Monday, October 27, 2008 7:59                        AM

                                              

Subject:                        Re: AC-680 FLP Engine RPM                        Fluctuation

                                              

 

                                                                                                                                                              

Tom, did you replace the lines                              with ones of the same Inside diameter?  Did you                              replace those on both sides of the flow divider                              (spider), and the fuel servo?

                                                          

 

                                                          

wer



--- On Mon,                              10/27/08, Tom Fisher <tfisher(at)commandergroup.bc.ca (tfisher(at)commandergroup.bc.ca)>                              wrote:

                             [quote]                               

From: Tom Fisher                                <tfisher(at)commandergroup.bc.ca (tfisher(at)commandergroup.bc.ca)>

Subject:                                Re: AC-680 FLP Engine RPM                                Fluctuation

To:                                commander-list(at)matronics.com

Date: Monday,                                October 27, 2008, 7:34 AM[quote]--> Commander-List message posted by: "Tom Fisher"<tfisher(at)commandergroup.bc.ca> I had the same surging problem on mine.I replaced all the upper deck lines with new stainless steel lines, the new lines also had to be welded in two places, this resolved the surging problem.TomC-GISS680FLP (Mr.RPM)---

BobsV35B(at)aol.com
Guest

Posted: Wed Oct 29, 2008 10:40 am Post subject: AC-680 FLP Engine RPM Fluctuation

Good Afternoon Robert,

  

 I have a friend who was involved as a mechanic with that project. He said  it was a beautiful running engine and that everything worked just as they had  expected it would. 

  

 Unfortunately, the interest in converting from a Turbine to a piston was  just not there. 

  

 I asked many of my King Air driver friends what they thought. Everyone of  them said there was no way they would ever go back to flying a piston. I got the  impression that it was an ego thing. They had no interest at all in the economy  or performance gains that might be achieved. They just wanted to arrive in a  turbine powered flying machine!

  

 Happy  Skies



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West 86th  Street

Downers Grove, IL 60516

630 985-8502 

Stearman  N3977A

Brookeridge Air Park LL22   

  In a message dated 10/29/2008 8:22:04 A.M. Central Daylight Time,  rsrandazzo(at)precisionmanuals.com writes:

  	  Quote: 	
		     

    

That    Mr. RPM test bed commander is currently on the ground in Midland TX and    according to some sources I checked with- it hasn't  been flying in some    time..   

    

Like    all things in GA- seems to be more heat than energy being generated on that    project.     

    

Robert    S.  Randazzo 	






Plan your next getaway with AOL Travel.  [url= http://travel.aol.com/discount-travel?ncid=emlcntustrav00000001 ]Check out Today's Hot 5 Travel Deals![/url]

  [quote][b]

nico(at)cybersuperstore.c
Guest

Posted: Wed Oct 29, 2008 11:36 am Post subject: AC-680 FLP Engine RPM Fluctuation

Well, Old Bob, there is  the safety of having much less moving parts in a turbine, too. And the moving  parts in a turbine just spin, they don't accellerate, stop, turn around,  accellerate, stop, turn around, accellerate thousands of times a minute either.  Seems to me they have my vote on that. However, going from an ageing Lycoming or  Continental to an Orenda would be a favorite for me. Provided they can last and  win some races and endurance rallies to increase their knowledge and  capabilities of the engines. 

  

 Nico

  

 

 

   From: owner-commander-list-server(at)matronics.com  [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of  BobsV35B(at)aol.com

Sent: Wednesday, October 29, 2008 11:38  AM

To: commander-list(at)matronics.com

Subject: Re:  AC-680 FLP Engine RPM Fluctuation

 

 Good Afternoon Robert,

  

 I have a friend who was involved as a mechanic with that project. He said  it was a beautiful running engine and that everything worked just as they had  expected it would. 

  

 Unfortunately, the interest in converting from a Turbine to a piston was  just not there. 

  

 I asked many of my King Air driver friends what they thought. Everyone of  them said there was no way they would ever go back to flying a piston. I got the  impression that it was an ego thing. They had no interest at all in the economy  or performance gains that might be achieved. They just wanted to arrive in a  turbine powered flying machine!

  

 Happy  Skies



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West 86th  Street

Downers Grove, IL 60516

630 985-8502 

Stearman  N3977A

Brookeridge Air Park LL22   

  In a message dated 10/29/2008 8:22:04 A.M. Central Daylight Time,  rsrandazzo(at)precisionmanuals.com writes:

  	  Quote: 	
		     

    

That    Mr. RPM test bed commander is currently on the ground in Midland TX and    according to some sources I checked with- it hasn't  been flying in some    time..   

    

Like    all things in GA- seems to be more heat than energy being generated on that    project.     

    

Robert    S.  Randazzo 	






   Plan your next getaway with AOL Travel. [url= http://travel.aol.com/discount-travel?ncid=emlcntustrav00000001]Check  out Today's Hot 5 Travel Deals![/url]

[quote]



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[b]

drwer2

Joined: 24 Sep 2008
Posts: 41
Location: Squaw Valley, CA

Posted: Wed Oct 29, 2008 12:15 pm Post subject: AC-680 FLP Engine RPM Fluctuation

While there may be a certain amount of ego associated with transitioning to Turbines, Owners will always go with what is most efficient and affordable.  The exception to this was the market shift from turbo-props to light jets.  None of the operators wanted to trade the efficiency of thier turbo props for the high initial and recurring costs of operating twin jets.  But, given the choice, people (not just pilots) loved flying in Jets!  Who cares if the cost of travel went up 20%.  You no doubt have noticed that all the regionals (in the black) are running Props again.  

  

 If you have an engine that has a TBO of 3500 to 5400 hrs, it could be made by Briggs and Stratton and would still find a home.  The pilot is the last opinion heard.

  

 Personally, I prefer a nice Big-Displacement, Geared, slow turning Piston. (560Fis my favorite) why?  Efficiency.  There isn't a law that says you have to fly full throttle.  Use your propeller performance curve and POH to tell you  your best cruise altitude and airspeed, and trim for that.  Use MRCP to get in and out effectively and then rein-in your ego.  There's nothing sexy about straight and level flight.

  

 Hoover was cool....but he didnt pay for the plane or the gas.

  

 wer



--- On Wed, 10/29/08, nico css <nico(at)cybersuperstore.com> wrote:



  	  Quote: 	
		  From: nico css <nico(at)cybersuperstore.com>

Subject: RE: AC-680 FLP Engine RPM Fluctuation

To: commander-list(at)matronics.com

Date: Wednesday, October 29, 2008, 12:33 PM



  Well, Old Bob, there is the safety of having much less moving parts in a turbine, too. And the moving parts in a turbine just spin, they don't accellerate, stop, turn around, accellerate, stop, turn around, accellerate thousands of times a minute either. Seems to me they have my vote on that. However, going from an ageing Lycoming or Continental to an Orenda would be a favorite for me. Provided they can last and win some races and endurance rallies to increase their knowledge and capabilities of the engines. 

  

 Nico

  

 

 

   From: owner-commander-list-server(at)matronics.com [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of BobsV35B(at)aol.com

Sent: Wednesday, October 29, 2008 11:38 AM

To: commander-list(at)matronics.com

Subject: Re: AC-680 FLP Engine RPM Fluctuation

 

 Good Afternoon Robert,

  

 I have a friend who was involved as a mechanic with that project. He said it was a beautiful running engine and that everything worked just as they had expected it would. 

  

 Unfortunately, the interest in converting from a Turbine to a piston was just not there. 

  

 I asked many of my King Air driver friends what they thought. Everyone of them said there was no way they would ever go back to flying a piston. I got the impression that it was an ego thing. They had no interest at all in the economy or performance gains that might be achieved. They just wanted to arrive in a turbine powered flying machine!

  

 Happy Skies



Old Bob

AKA

Bob Siegfried

Ancient Aviator

628 West 86th Street

Downers Grove, IL 60516

630 985-8502 

Stearman N3977A

Brookeridge Air Park LL22   

  In a message dated 10/29/2008 8:22:04 A.M. Central Daylight Time, rsrandazzo(at)precisionmanuals.com writes:

  	  Quote: 	
		   

 

 

That Mr. RPM test bed commander is currently on the ground in Midland TX and according to some sources I checked with- it hasn't  been flying in some time..

 

 

 

Like all things in GA- seems to be more heat than energy being generated on that project.  

 

 

 

Robert S. Randazzo

	






   Plan your next getaway with AOL Travel. Check out Today's Hot 5 Travel Deals!

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