K3 Vibration issues

[Dave F]

GSC has a 5 year limit on their blades, after 5 years of sitting or 500 hours of flying they recommend you send them in because of moisture and cracking. I just got off the phone with GSC and this is what Rick told me. We thought my prop was old but looking through the propeller logbook it is only about 2 years old, 1 year since installed and I'm still having some issues. He told me to send it in immediately because I should not have to pitch 19 degrees to hold 6,200 RPMS

Like I told you the other day -- 19 dgrees is just wrong unless you got about 80 to 90 HP or a gear box ratio higher thant 3 to 1...... have you counted the revolutions?

[Dave F]

Still having vibration issues on my 582 B-box with GSC prop. I noticed one blade is a 1/16" shorter than the other two. This is a factory new prop. Is this normal or maybe how they would balance the prop? I'm fixin to pull the prop and weight each blade. I also have a question on the old style motor lord mounts(flat plate). Do you tighten the bolts up to the inner sleeve or do they get torqued to some spec. Couldn't fine anything in my book.

I think that is just the nature of the beas for this type of mount.

That being said -- it is quite serviceable and you might have other issues

[Rmendler]

Did you tell Rick that you heard crushing noises as you tightened the prop?
ANd the alum blocks are near touching?

something odd here........

yes and apparently it is just the urethane on the blade roots compressing.

I also had a local A&P take a look while he was in the hanger, he thought the noise it was making was normal and he got 19 degrees of pitch when he used the protractor so I must be using it right.

The engine is still holding at 6,200 RPM's static. I guess there is the possibility someone has opened up my 582 in the past and done some work? I do notice the compression seems a little high compared to some other Rotax's here on the field.

And yes we pulled the prop through a few revolutions with a mark on the gearbox gear and it was 3:1 on the money.

[Dave F]

yes and apparently it is just the urethane on the blade roots compressing.

I also had a local A&P take a look while he was in the hanger, he thought the noise it was making was normal and he got 19 degrees of pitch when he used the protractor so I must be using it right.

The engine is still holding at 6,200 RPM's static. I guess there is the possibility someone has opened up my 582 in the past and done some work? I do notice the compression seems a little high compared to some other Rotax's here on the field.

And yes we pulled the prop through a few revolutions with a mark on the gearbox gear and it was 3:1 on the money.

Ok 3 to 1 -- we on the same page then.
582 power is somewhat limited due to port size and timing. The Rtoax exhaust is what alos caps the power on the 582 to give max torque around 6000 rpm or so...... static set it for 6000 to 6200 rpm with your prop pitch. Get all blades the same pitch AND CHECK TRACKING,,,,1/16 to 1/8" blade to blade is accetable.
ALso Kitfox shortened the stock 582 exhaust a bit on the Y pipe and the elbow to make a sidemount muffler work and it does work well. This is one reason the 582s seem to go a long distance on Kitfox's. don't worrry about this not a huge deal really. I have done a fair bit of experimenting on them and you can get more power but the space insode the stock cowl is an issue.

light brown on plus should be ok but EGT on the ground don't mean much....check in air....... EGT gauge is not a calibrated devie per say but a guide ot let you know what is going on inside the engine... plug colour is the true indicator over all.

as far as higher compression -- doubt it but who knows whadt some have done to engines......

[JimS]

Had a GSC on my Model 4 (c-box)for years that ran as smooth as a sewing machine. That being said, I worked with a friend on his Model 3 with a B box that shook like you are experiencing. Guages would actually blur at reduced throttle. One thing we did was loosen up the bolts going through the rubber motor mounts so the engine could shake but not as much was transfered to the rest of the airframe. Those bolts should not be tightened down. You should be able to move your spinner easily 1/4 inch by pushing on it a bit. (The model 4 mount was a big improvement.)
Next, are you measuring the prop pitch with the tail of the plane on the ground or with the plane in level atitude? Or are you factoring in the angle of attack during your pitch check?
Lastly, another friend damaged his GSC prop but had one good blade. He gave it to me and comparing it to my GSC it was apparent that I could never use that blade if I damaged one of mine as there was considerable more mass to his blade than the blades I had on my plane. Point being that lighter blades will run smoother. My prop was 1994 vintage, his was a few years older.
Good luck

JimS

[bbryan]

Just got back online, been working double shift for 2 weeks. Wow, thanks for all the responses. I just pulled the prop and put it on a 1 inch shaft, It seems the heavy blade is the short blade. Totally blew my idea of sanding the tips on the long blade to balance. I don't have a scales good enough to weigh each blade, but about a half of popsicle stick on the tips of the other two blades gets it close. I don't have enough experience with this to know if that is off balance a lot or not. How would I add weight to the two lighter blades. I thought about several coats of clearcoat to add weight. I don't want to cut more off the short blade. My load motor mounts are tight so I will also look into that. I really appreciate the feedback and got the pleasure of talking to Dave on the phone, what a storehouse of knowledge.