---------------------------------------------------------- Commander-List Digest Archive --- Total Messages Posted Tue 10/28/08: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:14 AM - Re: AC-680 FLP Engine RPM Fluctuation (willis robison) 2. 08:48 PM - Re: AC-680 FLP Engine RPM Fluctuation (Tom Fisher) 3. 09:05 PM - Re: AC-680 FLP Engine RPM Fluctuation (Don Barry Home) 4. 10:26 PM - Re: AC-680 FLP Engine RPM Fluctuation (nico css) ________________________________ Message 1 _____________________________________ Time: 08:14:14 AM PST US From: willis robison Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation Well, Next time you fly, once youve leaned for cruise, check the EGTs for t hose cylilnders that had the new lines welded.- If they are running withi n 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 wrote: From: Tom Fisher Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation Well, I am that much more informed, thanks for the info. Tom C-GISS ----- Original Message ----- From: willis robison Sent: Monday, October 27, 2008 11:54 AM Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation Thanks Tom. - Ive designed a few fuel systems and his symptoms are typical of a flowdivid er/lines on the hot side of an engine. (side downstream of an air cooled en gine)-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 som e 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 to p of the engine and then down.- Either way, cooling appears greatly reduc ed 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 bet ter, 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 t he pump on shutdown.- this immediately drops the pressure at the nozzles to zero... - 2. smaller lines have shorter fill times, quicker starts but are susceptibl e to vapor lock because they absorb heat faster.- At higher flowrates (ri ch) the delta-P loss in these lines may result in a higher vapor/liquid rat o- and thus a poorer spray patter at the nozzle.- This is more of an is sue on climbout on engines with poor cooling for whatever reason (like clos ed cowlvents, or just reduced airspeed (airflow)).- Modern fuellines in t hese situations are insulated (just like grandpas truck). - 3.- for systems with high flowrates (~100 pph or more) the different leng ths of fuel lines from the FDV to each nozzle becomes important.- there a re 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 i njectors...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 wrote: From: Tom Fisher Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation I got a new set from Mr.RPM himself so I assume they were of the same insid e diameter and yes his lines leaked and had to be welded in two places. I j ust replaced the lines from the flow divider to the cylinders. Tom. C-GISS - ----- Original Message ----- From: willis robison Sent: Monday, October 27, 2008 7:59 AM Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation Tom, did you replace the lines with ones of the same Inside diameter?- Di d you replace those on both sides of the flow divider (spider), and the fue l servo? - wer --- On Mon, 10/27/08, Tom Fisher wrote: From: Tom Fisher Subject: Re: Commander-List: 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) ----- Original Message ----- From: "Ray Mansfeld" Sent: Sunday, October 26, 2008 6:14 PM Subject: Commander-List: 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 > > > 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.m atronics.com/Navigator?Commander-List 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com /contribution 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.m atronics.com/Navigator?Commander-List 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com /contribution 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D =0A=0A=0A ________________________________ Message 2 _____________________________________ Time: 08:48:12 PM PST US From: "Tom Fisher" 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 ----- Original Message ----- From: willis robison To: commander-list@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 wrote: From: Tom Fisher Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation To: commander-list@matronics.com Date: Monday, October 27, 2008, 2:17 PM Well, I am that much more informed, thanks for the info. Tom C-GISS ----- Original Message ----- From: willis robison To: commander-list@matronics.com Sent: Monday, October 27, 2008 11:54 AM Subject: Re: Commander-List: 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 wrote: From: Tom Fisher Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation To: commander-list@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 ----- Original Message ----- From: willis robison To: commander-list@matronics.com Sent: Monday, October 27, 2008 7:59 AM Subject: Re: Commander-List: 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 wrote: From: Tom Fisher Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation To: commander-list@matronics.com Date: Monday, October 27, 2008, 7:34 AM 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) ----- Original Message ----- From: "Ray Mansfeld" Sent: Sunday, October 26, 2008 6:14 PM Subject: Commander-List: 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 > > > 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www .matronics.com/Navigator?Commander-List 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/contribution"'>http://www.matronics.c om/contribution 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www .matronics.com/Navigator?Commander-List 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D href='3D"http://www.matronics.com/contribution"'>http://www.matronics.c om/contribution 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D ________________________________ Message 3 _____________________________________ Time: 09:05:28 PM PST US From: "Don Barry Home" 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@matronics.com [mailto:owner-commander-list-server@matronics.com] On Behalf Of Tom Fisher Sent: Tuesday, October 28, 2008 10:46 PM 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 ----- Original Message ----- From: willis robison 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 wrote: From: Tom Fisher Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation Well, I am that much more informed, thanks for the info. Tom C-GISS ----- Original Message ----- From: willis robison Sent: Monday, October 27, 2008 11:54 AM Subject: Re: Commander-List: 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 wrote: From: Tom Fisher Subject: Re: Commander-List: 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 ----- Original Message ----- From: willis robison Sent: Monday, October 27, 2008 7:59 AM Subject: Re: Commander-List: 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 wrote: From: Tom Fisher Subject: Re: Commander-List: 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) ----- Original Message ----- From: "Ray Mansfeld" Sent: Sunday, October 26, 2008 6:14 PM Subject: Commander-List: 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 > > > > > 3D=========================3 D=================== href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.matr onics.com/Navigator?Commander-List 3D=========================3 D=================== href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=========================3 D=================== href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com/co ntribution 3D=========================3 D=================== 3D=========================3 D=================== href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.matr onics.com/Navigator?Commander-List 3D=========================3 D=================== href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=========================3 D=================== href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com/co ntribution 3D=========================3 D=================== 3D=========================3 D=================== href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.matr onics.com/Navigator?Commander-List 3D=========================3 D=================== href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=========================3 D=================== href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com/co ntribution 3D=========================3 D=================== ________________________________ Message 4 _____________________________________ Time: 10:26:42 PM PST US From: "nico css" Subject: RE: Commander-List: 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@matronics.com [mailto:owner-commander-list-server@matronics.com] On Behalf Of Don Barry Home Sent: Tuesday, October 28, 2008 9:00 PM 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@matronics.com [mailto:owner-commander-list-server@matronics.com] On Behalf Of Tom Fisher Sent: Tuesday, October 28, 2008 10:46 PM 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 ----- Original Message ----- From: willis robison 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 wrote: From: Tom Fisher Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation Well, I am that much more informed, thanks for the info. Tom C-GISS ----- Original Message ----- From: willis robison Sent: Monday, October 27, 2008 11:54 AM Subject: Re: Commander-List: 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 wrote: From: Tom Fisher Subject: Re: Commander-List: 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 ----- Original Message ----- From: willis robison Sent: Monday, October 27, 2008 7:59 AM Subject: Re: Commander-List: 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 wrote: From: Tom Fisher Subject: Re: Commander-List: 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) ----- Original Message ----- From: "Ray Mansfeld" Sent: Sunday, October 26, 2008 6:14 PM Subject: Commander-List: 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 > > > > > 3D=========================3 D=================== href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.matr onics.com/Navigator?Commander-List 3D=========================3 D=================== href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=========================3 D=================== href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com/co ntribution 3D=========================3 D=================== 3D=========================3 D=================== href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.matr onics.com/Navigator?Commander-List 3D=========================3 D=================== href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=========================3 D=================== href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com/co ntribution 3D=========================3 D=================== 3D=========================3 D=================== href='3D"http://www.matronics.com/Navigator?Commander-List"'>http://www.matr onics.com/Navigator?Commander-List 3D=========================3 D=================== href='3D"http://forums.matronics.com"'>http://forums.matronics.com 3D=========================3 D=================== href='3D"http://www.matronics.com/contribution"'>http://www.matronics.com/co ntribution 3D=========================3 D=================== http://www.matronics.com/contribution ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message commander-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Commander-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/commander-list Browse Digests http://www.matronics.com/digest/commander-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.