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Wierd prop noise, 600RPM


Animosity2k

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2012 CTLSi TT 239hr

So it was 32* out today so I decided to go up to the hangar and hour and a half before departing and turn on my 1500w ceramic heater to pipe some heat into the cowling. When I pulled the plane out and started up it up I had a 71* oil temp however the tach/engine was making an ungodly awful sound. I turned it off, waited 5 minutes and restarted but this time cracked the throttle a tad. RPMS moved up to 2200 so I backed down to idle and warmed it up to 120* at idle.  Anyone know what this could have been? On my preflight the oil was low so I burped the prop to make sure I was in the middle of the dip stick which I was. Regardless flew problem free for 2 hours and all gauges and sounds were good.

Thanks in advance! 

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11 hours ago, Anticept said:

If the engine was spinning at 600 RPM after you got off the starter, that's the reason for the unholy noise. It's not designed to run at 600 RPM. It will make all sorts of awful scary noise, and that's why it went away when the RPM was higher.

Think I am more than likely ok then given it ran fine after? 

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If it sounds and feels fine at >1600 rpm, you're fine.

It's not designed to run at 600 RPM. It will want to jump its mounts. The firing impulses will be shaking the engine line crazy. The gearbox clutch and dog gear system will be rebounding badly as it tries to absorb the stress.

The faster a recip engine runs, the smoother it will be.

Anyways, you should also know that air blast preheating does a really poor job of actually preheating. It takes time for an engine to heat soak. The last parts to recieve heat are the main bearings and crankshaft journals, and they need the heat.

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3 hours ago, Anticept said:

If it sounds and feels fine at >1600 rpm, you're fine.

It's not designed to run at 600 RPM. It will want to jump its mounts. The firing impulses will be shaking the engine line crazy. The gearbox clutch and dog gear system will be rebounding badly as it tries to absorb the stress.

The faster a recip engine runs, the smoother it will be.

Anyways, you should also know that air blast preheating does a really poor job of actually preheating. It takes time for an engine to heat soak. The last parts to recieve heat are the main bearings and crankshaft journals, and they need the heat.

Corey then perhaps it maybe just wasn't as warm as indicated? The rough sound definitely sounds like it could have been the engine buckling in the mounts it was very nasty sounding but was not there the second start ; again perhaps having the throttle cracked a bit helped with that. I really don't want to drop $1,000 on a engine pre-heater given I only plane to fly 4-5 times a winter. If my hangar gets down to 30* or so is it a bad idea to start altogether? 

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Reiff heaters are far far less than that.

Rotax engines will be fine starting in the cold, you just need to make sure that you don't let it sit there and shake itself apart at 600 RPM. Cracking the throttle was fine.

Just give it ample time to warm up before you accelerate the throttle too much, because the oil will be pretty thick. The worst thing you can do is push the throttle forward too soon, and end up with oil film breakage. That will greatly accelerate wear it wherever it contacts.

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15 hours ago, Anticept said:

Reiff heaters are far far less than that.

Rotax engines will be fine starting in the cold, you just need to make sure that you don't let it sit there and shake itself apart at 600 RPM. Cracking the throttle was fine.

Just give it ample time to warm up before you accelerate the throttle too much, because the oil will be pretty thick. The worst thing you can do is push the throttle forward too soon, and end up with oil film breakage. That will greatly accelerate wear it wherever it contacts.

Ok so if I just crack it a bit every cold start to avoid the 600RPM and let it sit cracked @ like 2,000 and run it from say 45* to 120* I should be fine? Reiff installs pretty easy to do for someone now mechanically inclined? 

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On 12/17/2019 at 11:40 AM, Animosity2k said:

Ok so if I just crack it a bit every cold start to avoid the 600RPM and let it sit cracked @ like 2,000 and run it from say 45* to 120* I should be fine? Reiff installs pretty easy to do for someone now mechanically inclined? 

Reiff instructions are generic for a 912 series, not specific to Flight Design, so it requires some thought on routing and attaching wires.  The process is fairly straightforward, but to gain access to lower engine area I removed one front exhaust tube, so there is a bit "work" but nothing too challenging.   The epoxy used to attach the heater to case, and temp sensor to oil tank, requires 48 hours to cure at temperature of 75F minimum.  I did my install in the fall, and used a blue tarp over the engine area with small room heater, and a thermometer hung up by engine to monitor the process.  Holding these in place until epoxy kicks is important, I made a wood support stick that ran down to floor, then wedged it in to apply the required amount of holding force.  This worked great, and needs to be just a bit longer than height to ground, so force is straight on to the element - otherwise side forces will allow the epoxy to creep location and element will shift.

I've been very pleased with how this little 150W system works.  Mild days I plug in maybe 4 or so hours prior to launch.  Cold days I start the night before.  I know there are negative opinions on risk of heater element degrading the carbon mount for oil tank.  I've yet to see any issues, but don't leave it on running for days either.  For the price and performance I'm not concerned on the tank mount, if I develop an issue I'll fabricate one from aluminum, or pick up a used one, they are replaceable so not a huge risk as I see it.

I'll snap some pictures of how I ran my wiring, and general layout, when I have cowl off for an oil change before long.

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16 minutes ago, GrassStripFlyBoy said:

Reiff instructions are generic for a 912 series, not specific to Flight Design, so it requires some thought on routing and attaching wires.  The process is fairly straightforward, but to gain access to lower engine area I removed one front exhaust tube, so there is a bit "work" but nothing too challenging.   The epoxy used to attach the heater to case, and temp sensor to oil tank, requires 48 hours to cure at temperature of 75F minimum.  I did my install in the fall, and used a blue tarp over the engine area with small room heater, and a thermometer hung up by engine to monitor the process.  Holding these in place until epoxy kicks is important, I made a wood support stick that ran down to floor, then wedged it in to apply the required amount of holding force.  This worked great, and needs to be just a bit longer than height to ground, so force is straight on to the element - otherwise side forces will allow the epoxy to creep location and element will shift.

I've been very pleased with how this little 150W system works.  Mild days I plug in maybe 4 or so hours prior to launch.  Cold days I start the night before.  I know there are negative opinions on risk of heater element degrading the carbon mount for oil tank.  I've yet to see any issues, but don't leave it on running for days either.  For the price and performance I'm not concerned on the tank mount, if I develop an issue I'll fabricate one from aluminum, or pick up a used one, they are replaceable so not a huge risk as I see it.

I'll snap some pictures of how I ran my wiring, and general layout, when I have cowl off for an oil change before long.

Photos would be great, ordered the 250w version which will be here tomorrow and looking forward to getting it installed! Do you just drive to hangar and plug it in or have a remote setup to turn it on? Wheres the plug go?

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I'll get on pictures within a day or two.  I'm fortunate to have my hanger in the backyard on a private airport, so don't have to deal with remote operation.  Many people have posted options on remote triggers across the web, I think EAA Sport Aviation just had an article about using a dirt cheap cell phone plan with texting function to trigger a switch, hunt for that.

The Reiff system comes with a standard three prong 110v grounded plug, and instructions call for that to be routed to oil access door, or cowl opening.   The Reiff components ship with connectors installed to easily assemble the system (heater elements / temp sensor / Y connectors / and this 110 end plug)  I saved the weight and hassle of having to install this last leg of the wire harness, as the middle harness was long enough to reach to lower bottom firewall cowl opening.  I think this made for more streamlined wire routing, otherwise I'd have to spool up the excess length, and also did not want to keep the oil door open allowing heat loss. 

The 250w version will have 2 of the 100W elements, so you will have to access both sides of the engine case, so a bit more work there.  Be sure to mix the epoxy very well, it is super thick, warm it up prior to mixing.  Then have plenty of popsicle sticks for spreading it on the element, and paper towels handy for clean up.  Make it as uniform and pretty as you can on the element, once you stick to engine it would be a pain and mess to pull it back out.  Practice the hand moves to install it, and the supports to hold things in place, then when feeling you're good with set up have at the epoxy step.  I used a small piece of wood and duct tape to hold the temp sensor to tank bottom when gluing that, which was easy enough. 

Pulling the exhaust is easy but the springs can be a challenge.  Tom Baker's process of making safety wire tool with loops worked super well.  I'll take a pic of that too.  I would not want to try installing these without the access of removing front exhaust tube.  That is a good skill to learn beyond this project.

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16 hours ago, GrassStripFlyBoy said:

I'll get on pictures within a day or two.  I'm fortunate to have my hanger in the backyard on a private airport, so don't have to deal with remote operation.  Many people have posted options on remote triggers across the web, I think EAA Sport Aviation just had an article about using a dirt cheap cell phone plan with texting function to trigger a switch, hunt for that.

The Reiff system comes with a standard three prong 110v grounded plug, and instructions call for that to be routed to oil access door, or cowl opening.   The Reiff components ship with connectors installed to easily assemble the system (heater elements / temp sensor / Y connectors / and this 110 end plug)  I saved the weight and hassle of having to install this last leg of the wire harness, as the middle harness was long enough to reach to lower bottom firewall cowl opening.  I think this made for more streamlined wire routing, otherwise I'd have to spool up the excess length, and also did not want to keep the oil door open allowing heat loss. 

The 250w version will have 2 of the 100W elements, so you will have to access both sides of the engine case, so a bit more work there.  Be sure to mix the epoxy very well, it is super thick, warm it up prior to mixing.  Then have plenty of popsicle sticks for spreading it on the element, and paper towels handy for clean up.  Make it as uniform and pretty as you can on the element, once you stick to engine it would be a pain and mess to pull it back out.  Practice the hand moves to install it, and the supports to hold things in place, then when feeling you're good with set up have at the epoxy step.  I used a small piece of wood and duct tape to hold the temp sensor to tank bottom when gluing that, which was easy enough. 

Pulling the exhaust is easy but the springs can be a challenge.  Tom Baker's process of making safety wire tool with loops worked super well.  I'll take a pic of that too.  I would not want to try installing these without the access of removing front exhaust tube.  That is a good skill to learn beyond this project.

Sounds good would appreciate the photos. 

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