---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Sat 11/20/10: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:34 AM - Re: Re: Rotax 912 throttle return springs (Matt Tucciarone) 2. 05:02 AM - Re: Rotax 912 throttle return springs (Thom Riddle) 3. 05:15 AM - Re: Re: Rotax 912 throttle return springs (Matt Tucciarone) 4. 05:35 AM - Re: Rotax 912 throttle return springs (Thom Riddle) 5. 07:34 AM - Re: Re: Rotax 912 throttle return springs (Jerry) 6. 07:45 AM - Re: Re: Rotax 912 throttle return springs (Carl) 7. 10:39 AM - Rough running cured with carb heater (=?ISO-8859-1?Q?J=F3hann_J=F3hannsson?=) 8. 02:56 PM - Re: Rough running cured with carb heater (Gordon) 9. 03:27 PM - Re: Rough running cured with carb heater (=?ISO-8859-1?Q?J=F3hann_J=F3hannsson?=) 10. 03:31 PM - Re: Rough running cured with carb heater (Roger Lee) 11. 03:49 PM - Re: Rotax 912 throttle return springs (Roger Lee) 12. 03:55 PM - Re: Re: Rough running cured with carb heater (=?ISO-8859-1?Q?J=F3hann_J=F3hannsson?=) 13. 05:24 PM - Re: Rough running cured with carb heater (Chris Blackmore) ________________________________ Message 1 _____________________________________ Time: 04:34:13 AM PST US From: "Matt Tucciarone" Subject: Re: RotaxEngines-List: Re: Rotax 912 throttle return springs I think it is a good idea to have the throttle wide open in case of a cable break. But I have always wondered how long the 912S would go on full throttle. I was taught to use full throttle on take-off for a few minutes and then 5500 max cruise. Would not the engine just blow up? -----Original Message----- From: Thom Riddle Sent: Friday, November 19, 2010 7:35 AM Subject: RotaxEngines-List: Re: Rotax 912 throttle return springs It is standard aviation practice to spring load the throttle arm to wide open. Several years ago, one my partners in a Cherokee 140 had the throttle cable break during flight and it went to full throttle which enabled him to get home and landed deadstick after turning off the fuel and then the mags. Cable replaced and we were back to flying. -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Everyone is entitled to his own opinion, but not his own facts. Daniel Patrick Moynihan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=320068#320068 ________________________________ Message 2 _____________________________________ Time: 05:02:12 AM PST US Subject: RotaxEngines-List: Re: Rotax 912 throttle return springs From: "Thom Riddle" If your prop pitch is set properly (5,500 rpm with WOT in straight and level flight), then the only time you would overspeed the engine would be in descent. The engine is good for 5500 rpm all day long. When it comes time to descend, if you want to save your engine, then you turn the fuel off and when the engine dies, you cut off the mags and do a dead-stick approach and landing. You will have to cut the engine off anyway at some point or you won't be able to get your speed down to normal approach airspeed, so you might as well do it before you start your descent. -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Everyone is entitled to his own opinion, but not his own facts. Daniel Patrick Moynihan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=320151#320151 ________________________________ Message 3 _____________________________________ Time: 05:15:24 AM PST US From: "Matt Tucciarone" Subject: Re: RotaxEngines-List: Re: Rotax 912 throttle return springs I never tried strait and level at full throttle. My engine goes to 5800 on take off. It was set up that way when I bought it. I fly low, so I would imagine it would go past 5800 in strait and level. What are your engines doing on take off? -----Original Message----- From: Thom Riddle Sent: Saturday, November 20, 2010 7:59 AM Subject: RotaxEngines-List: Re: Rotax 912 throttle return springs If your prop pitch is set properly (5,500 rpm with WOT in straight and level flight), then the only time you would overspeed the engine would be in descent. The engine is good for 5500 rpm all day long. When it comes time to descend, if you want to save your engine, then you turn the fuel off and when the engine dies, you cut off the mags and do a dead-stick approach and landing. You will have to cut the engine off anyway at some point or you won't be able to get your speed down to normal approach airspeed, so you might as well do it before you start your descent. -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Everyone is entitled to his own opinion, but not his own facts. Daniel Patrick Moynihan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=320151#320151 ________________________________ Message 4 _____________________________________ Time: 05:35:11 AM PST US Subject: RotaxEngines-List: Re: Rotax 912 throttle return springs From: "Thom Riddle" m.tucciarone, You are losing a lot of cruise speed with the prop pitch set for 5800 rpm during climb but getting better climb performance that you will with a little more pitch. I've owned three airplanes with 912 engines. With the prop pitch set for 5500 rpm at WOT in S&L flight, the climb-out rpm at Vy depends upon which prop you have and on what airframe. Mine varied from about 4800 rpm to 5100 rpm at Vy climb at WOT. With a given prop, the faster the airframe, the lower the Vy climb WOT engine rpm will be, and vice versa. -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 Everyone is entitled to his own opinion, but not his own facts. Daniel Patrick Moynihan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=320154#320154 ________________________________ Message 5 _____________________________________ Time: 07:34:03 AM PST US From: Jerry Subject: RE: RotaxEngines-List: Re: Rotax 912 throttle return springs I actually had a throttle cable break on a Super Cub. It also has a throttle spring that went full throttle. After a little thought I used the mixture control to control the rpm and was able to land with no issue. Because of this incident, I've given some thought of what to do if the same thing happens with my 912 and you're in flight. The first thing to do is to turn one of the ignitions off. The rpm will be reduced by a couple of hundred rpm. Then you turn the other mag on and off to control the rpm, similar to what was done in WWI with one of the motors used back then. A little inconvenient but doable. If your WOT setting is set above 5500 you should be able to keep the motor from being damaged while finding a place to make a safe landing. Jerry ________________________________ Message 6 _____________________________________ Time: 07:45:03 AM PST US From: Carl Subject: Re: RotaxEngines-List: Re: Rotax 912 throttle return springs Listers. Interesting discussion. I'm squarely in the" don't screw around with the return springs" group but will add a few extra thoughts to ponder. Depending where the linkage breaks the situation will vary from both carbs fully open to an out of sync situation. The first case should become obvious fairly quickly when power is adjusted . The second may not be so obvious and present and engine that is fairly happy with throttle at near full power, to one that is running very rough and developing no power when throttle is at idle. Given the above we may want to review our check list for rough a running engine? When only one carb is affected it should be possible to modulate power at the top end with the one controlled carb to prevent over speed and complete a controlled descent to an approach then shutting the engine when the landing is assured? Happy landings Carl ----- Original Message ----- From: Carlos Trigo To: rotaxengines-list@matronics.com Sent: Friday, November 19, 2010 5:23 AM Subject: RE: RotaxEngines-List: Re: Rotax 912 throttle return springs Dan In the first case you mentioned, when taxiing in a public airport and your engine goes WOT, you just flip your ignition switches to OFF, to avoid running into that expensive King Air. In the other case, when only one cable will brake, you will certainly prefer to have a very rough running engine, but still be able to reach a suitable landing spot, than to choose the best tree branch to hit. Please believe that those Rotax engineers already thought on all the possibilities, before deciding to put those return springs. Carlosh ------------------------------------------------------------------------- ----- From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Dan Billingsley Sent: sexta-feira, 19 de Novembro de 2010 9:00 To: rotaxengines-list@matronics.com Subject: Re: RotaxEngines-List: Re: Rotax 912 throttle return springs Richard, Having the carbs go to wide open might be a good thing as long as you are flying over a place you would never want to put down, however, there are other places I can think of it would be a disaster...think of taxiing in a public airport and then your engine goes wide open. I'm sure running into that King Air would ruin your day. I know many folks who take the springs off and leave them off. The other thing to think about is we have two carbs. What are the odds both of the throttle cables will fail at the same time? More than likely one will go and then you will have a very rough running engine with the carbs out of balance. Just my 2 cents From: Richard Girard To: rotaxengines-list@matronics.com Sent: Thu, November 18, 2010 9:33:45 PMo Subject: Re: RotaxEngines-List: Re: Rotax 912 throttle return springs Noel, You're right about the Bing 54 on the 582, a fact that keeps my cables lubed and inspected to excess. Which would you rather have if a throttle cable breaks an engine at WOT or an engine at idle. Think miles of trees underneath you and no clearing in sight. Jim, The throttle cable on the Bing 64 is connected to the throttle butterfly, not the piston. The butterfly sets the throttle and the piston does fine adjustment of the mixture my raising and lowering the jet needle in response to atmospheric pressure. Joel, if that was your comment in the tiny, tiny print about changing over the throttle springs to pull the butterfly to idle, wheel chocks and checking the throttle position before starting the engine can keep your plane from running away. IF you're at 2000' over a forest with your wife or child on board when a throttle cable breaks and the engine goes to idle, I truly doubt you'll be calling that a "Safety Feature" right about then. Rick Girard On Thu, Nov 18, 2010 at 8:24 PM, Noel Loveys wrote: Then the question should be why have a spring at all... From what I see all it does is put pressure on the throttle cables. Wouldn't it be better not to have springs at all? BTW the 582 with the Bing carbs will go to idle if the cable breaks Noel From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Richard Girard Sent: November 18, 2010 6:59 PM To: rotaxengines-list@matronics.com Subject: Re: RotaxEngines-List: Re: Rotax 912 throttle return springs Barry, Unlike those on an automobile or other conveyance, the throttle return spring on an aircraft is there to make sure that if the throttle cable breaks the carb goes to wide open throttle. Rick Girard On Thu, Nov 18, 2010 at 12:41 PM, FLYaDIVE wrote: Hey Guys: I know I'm late on entering this Throttle Return Spring discussion. But the questions I have are: 1 - Why is there a throttle return spring? 2 - What position does it return the Throttle to? Barry On Thu, Nov 18, 2010 at 8:04 AM, Thom Riddle wrote: I've never seen these springs to get noticeably weaker over time. I'm not saying they can't but spring steel takes a VERY LONG time to loose its springiness in normal service. I suspect your cables might need lubrication or they have a tighter radius than desirable -------- Thom Riddle Buffalo, NY (9G0) Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 "Everyone is entitled to his own opinion, but not his own facts." Daniel Patrick Moynihan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=319901#319901 ========== ="_blank">www.aeroelectric.com ooks.com" target="_blank">www.buildersbooks.com et="_blank">www.homebuilthelp.com ="_blank">http://www.matronics.com/contribution le, List Admin. ========== -List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List ========== http://forums.matronics.com ========== _blank">www.aeroelectric.com.com" target="_blank">www.buildersbooks.com="_blank">www.homebuilthelp.com_ blank">http://www.matronics.com/contributionist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-Listtp: //forums.matronics.com -- Zulu Delta Kolb Mk IIIC 582 Gray head 4.00 C gearbox 3 blade WD Thanks, Homer GBYM It is not bigotry to be certain we are right; but it is bigotry to be unable to imagine how we might possibly have gone wrong. - G.K. Chesterton www.aeroelectric.comwww.buildersbooks.comwww.homebuilthelp.comhttp://www. matronics.com/contributionhttp://www.matronics.com/Navigator?RotaxEngines -Listhttp://forums.matronics.com _blank">www.aeroelectric.com.com" target="_blank">www.buildersbooks.com="_blank">www.homebuilthelp.com_ blank">http://www.matronics.com/contributionist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-Listtp: //forums.matronics.com -- Zulu Delta Kolb Mk IIIC 582 Gray head 4.00 C gearbox 3 blade WD Thanks, Homer GBYM It is not bigotry to be certain we are right; but it is bigotry to be unable to imagine how we might possibly have gone wrong. - G.K. Chesterton = * AeroElectric www.homebuilthelp> http://www.matronics.com/Navigator?RotaxEngines-Li======== === www.aeroelectric.comwww.homebuilthelp.comhttp://www.matronics.com/contrib utionwww.aeroelectric.com ________________________________ Message 7 _____________________________________ Time: 10:39:08 AM PST US From: =?ISO-8859-1?Q?J=F3hann_J=F3hannsson?= Subject: RotaxEngines-List: Rough running cured with carb heater Hello list members. I have a friend who has been having problems with the Rotax 912 UL in a Kitfox 3. When flying today in a temp. around 40F, the engine ran rough until he pulled the carb heat on. Ran very smooth and never as good. What do you think could cause this problem? We measured the carb levels and they are very similar. 1/8 of an inch. One carb was definitely running bad because the EGT dropped on one exhaust. No carb ice and the carbs have been rebuild. Any ideas? Johann G. Iceland. Zenith 701 Rotax 912UL. ________________________________ Message 8 _____________________________________ Time: 02:56:30 PM PST US From: "Gordon" Subject: Re: RotaxEngines-List: Rough running cured with carb heater Carb heat bypasses the air filter, at least on most set-ups, so maybe a clogged filter. It also introduces warm air which is less dense, so it could be that the mixture of one or both carbs is set to lean for the normal (cold) air --my guess. Gordon ----- Original Message ----- From: "Jhann Jhannsson" Sent: Saturday, November 20, 2010 1:33 PM Subject: RotaxEngines-List: Rough running cured with carb heater > =?ISO-8859-1?Q?J=F3hann_J=F3hannsson?= > > Hello list members. > > I have a friend who has been having problems with the Rotax 912 UL in a > Kitfox 3. When flying today in a temp. around 40F, the engine ran rough > until he pulled the carb heat on. Ran very smooth and never as good. > What do you think could cause this problem? We measured the carb levels > and they are very similar. 1/8 of an inch. One carb was definitely > running bad because the EGT dropped on one exhaust. > No carb ice and the carbs have been rebuild. Any ideas? > > Johann G. > Iceland. > Zenith 701 > Rotax 912UL. > > > ________________________________ Message 9 _____________________________________ Time: 03:27:33 PM PST US From: =?ISO-8859-1?Q?J=F3hann_J=F3hannsson?= Subject: Re: RotaxEngines-List: Rough running cured with carb heater Thank you Gordon. I know my friend has a new air filter and the airbox does eliminate the cold air from the filter and only passes the hot air from the exhaust pipe. We will look at the mixture setting. Thanks again. Johann G. Iceland. On 20.11.2010, at 22:49, Gordon wrote: > > Carb heat bypasses the air filter, at least on most set-ups, so > maybe a clogged filter. > It also introduces warm air which is less dense, so it could be that > the mixture of one or both carbs is set to lean for the normal > (cold) air --my guess. > Gordon > ----- Original Message ----- From: "Jhann Jhannsson" > > To: > Sent: Saturday, November 20, 2010 1:33 PM > Subject: RotaxEngines-List: Rough running cured with carb heater > > >> J=F3hann_J=F3hannsson?= >> >> Hello list members. >> >> I have a friend who has been having problems with the Rotax 912 UL >> in a Kitfox 3. When flying today in a temp. around 40F, the >> engine ran rough until he pulled the carb heat on. Ran very smooth >> and never as good. >> What do you think could cause this problem? We measured the carb >> levels and they are very similar. 1/8 of an inch. One carb was >> definitely running bad because the EGT dropped on one exhaust. >> No carb ice and the carbs have been rebuild. Any ideas? >> >> Johann G. >> Iceland. >> Zenith 701 >> Rotax 912UL. >> >> >> >> > > ________________________________ Message 10 ____________________________________ Time: 03:31:51 PM PST US Subject: RotaxEngines-List: Re: Rough running cured with carb heater From: "Roger Lee" Three things I would do. Have the carbs been pneumatically balanced? If yes move on, if no do it. Are the carb vent tubes in their proper place? Check these to see if one moved. When the carbs were rebuilt did the person put the diaphragm notch in the proper place? You will need to pull the top off each carb to check this, but this is easy. Clogged filter as suggested maybe, but I don't think of Iceland as being really dusty. It takes quite a bit to cause this. If you are using a K&N filter and over saturate it with oil this will cause a leaning issue and opening the carb heat would let in more air. What type of airbox does it have? A standard Rotax airbox or two individual filters? When you say carb levels do you mean float levels? Whom ever rebuilt these should have checked the float arm measurement when he rebuilt these. If he didn't this may cause a rough running carb. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center Home 520-574-1080 TRY HOME FIRST Cell 520349-7056 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=320201#320201 ________________________________ Message 11 ____________________________________ Time: 03:49:41 PM PST US Subject: RotaxEngines-List: Re: Rotax 912 throttle return springs From: "Roger Lee" Thom has it right. Your WOT rpm should be right around 5500 rpm. 5450-5550 rpm WOT flat and level. The proper check if you have a sudden large vibration and power issue should be to try WOT and see if it smooths out. If it does then somewhere in your cable setup it has disengaged from one carb and it is now wide open. If it doesn't then it's time to land very quickly. If your rpm is set to 5500 WOT then you can fly anywhere and into the pattern. When you are on finial and know you have the field made just shut down and glide in dead stick. Dead stick really is no big deal and should be practiced once in a while. It isn't any different than with power so long as you keep your speed up. Yes I know there is no go around at that point, so pay extra attention to your approach and landing. When I'm dead stick I keep 5-10 mph over my normal approach to help make sure I don't get any surprises at the bottom with wind or failure to watch my speed and dip too far below a safe approach speed. I never approach too slow any way so 5-10 extra for me gives me a healthy safety margin. You can always bleed extra speed off down on the runway, but you may not be high enough to get it back if you are one of those that like to drag it in. If you are from the old Ultralight days then you are used to doing dead stick landings. p.s. Leave your springs alone. They are the way they are for a very good reason. If yours isn't acting right then fix the problem in your throttle system and leave the springs alone. This goes back to my mantra. The worst thing that happens to a Rotax engine is it's owner. Work safe, Be safe so you can fly safe and come home to hug the wife, girlfriend and I have to include significant other, too. [Wink] -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center Home 520-574-1080 TRY HOME FIRST Cell 520349-7056 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=320204#320204 ________________________________ Message 12 ____________________________________ Time: 03:55:59 PM PST US From: =?ISO-8859-1?Q?J=F3hann_J=F3hannsson?= Subject: Re: RotaxEngines-List: Re: Rough running cured with carb heater Hello Roger. Thank you very much for all these points. We will check on them all. Not sure how the vent tubes are on his plane. Easy to find out tomorrow. The diaphragms are new and are correctly installed in the notch. He is using one big K&N filter and it is clean. Yes, I meant to say the float level. The Airbox is something made by the builder. Maybe it is not working properly. I think it is a standard item for the Kitfox. First we will do the balancing again, and check the vent tubes. Thanks again. Johann G. Iceland. On 20.11.2010, at 23:29, Roger Lee wrote: > > > > Three things I would do. > Have the carbs been pneumatically balanced? If yes move on, if no do > it. > Are the carb vent tubes in their proper place? Check these to see if > one moved. > When the carbs were rebuilt did the person put the diaphragm notch > in the proper place? You will need to pull the top off each carb to > check this, but this is easy. > Clogged filter as suggested maybe, but I don't think of Iceland as > being really dusty. It takes quite a bit to cause this. If you are > using a K&N filter and over saturate it with oil this will cause a > leaning issue and opening the carb heat would let in more air. What > type of airbox does it have? A standard Rotax airbox or two > individual filters? > > When you say carb levels do you mean float levels? Whom ever rebuilt > these should have checked the float arm measurement when he rebuilt > these. If he didn't this may cause a rough running carb. > > -------- > Roger Lee > Tucson, Az. > Light Sport Repairman - Maintenance Rated > Rotax Repair Center > Home 520-574-1080 TRY HOME FIRST > Cell 520349-7056 > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=320201#320201 > > ________________________________ Message 13 ____________________________________ Time: 05:24:06 PM PST US From: "Chris Blackmore" Subject: Re: RotaxEngines-List: Rough running cured with carb heater ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-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/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-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.