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Gearbox/prop

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Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Mon Aug 02, 2010 4:40 am Post subject: Gearbox/prop

This is just an update on the Paradise P-1 we have been working on. To review, the aircraft had developed a vibration at cruise rpms that could be felt thruout the aircraft in flight and on the ground. After much testing (carbs,prop pitch,tracking,etc) it was decided to pull the gearbox and send it to Lockwood for overhaul. The aircraft has less than 300 hrs since new, the torque friction test was OK albeit on the lower side compared to another Paradise of equal vintage (3years old) I personally couldn't see how it could be the box but the owner wanted to do it so. Lockwood inspected the box, said it looked fine,reshimmed it and sent it back with new belville washers. We reinstalled it and he flew it yesterday. Vibration is gone! Well, almost.There is just a hair. He has ordered and will be installing a new Kiev prop vs the square tip Warp on the aircraft. The Kiev is lighter and has been much smoother on the few Paradise aircraft we have here. Cruise speed has also increased.

  I have also removed the taper tip,nickle edge Warp on my Kitfox and have installed the Kiev. It has made a dramatic difference for my aircraft! The Kiev is very quiet and as smooth as a turbine and more importantly, I am no longer plagued with the kickback problem I was having on shutdown. I haven't realized an increase in cruise speed ,however as in the Paradise

  Please don't get me wrong, that Warp is tough as nails and I do like it but the Kiev has solved my problems.

  The Lockwood tech was not suprised that the gearbox reshim /correct propellor combo solved the problem as they have dealt with that many times before even with low time engines.

  I just relate this story because sometimes things are not what they seem. I was absolutely sure the gearbox was not a problem. Maybe the "heavier" Warp was creating more wear, weaker bellview springs, who knows?

                                                      Dick Maddux

                                                      912UL

                                                      Milton,Fl 

  [quote][b]

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Mon Aug 02, 2010 5:48 am Post subject: Re: Gearbox/prop

Hi Dick,



Glad it finally worked out for you. Sometimes finding a problem is like chasing a ghost.

Rotax is fairly adamant about not using anything over 68" from Warp and absolutely no nickel edges. I have a 66" Warp on my plane. I will say after doing this for years now that the heavy props will take their toll on a gearbox over time and you won't even know it until it's too late and you need a gearbox rebuild. The lighter the prop the better off you are and make sure you do at least a static balance on a new prop. This is another reason everyone should do the gearbox friction torque test as I mentioned in another post. This will help determine if you are headed down hill in the gearbox.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Mon Aug 02, 2010 8:24 am Post subject: Gearbox/prop

Dick, Rotax has a spec for prop balance of .5 gram (Installation Manual, page 121). A small nick, abrasion from high grass, even cleaning the propeller with strong cleaning agents or abrasives, particularly if they remove the paint which WD uses for fine balance, can effect this in a negative way. Have you balanced your prop lately? 



Rick Girard



On Mon, Aug 2, 2010 at 7:39 AM,  <Catz631(at)aol.com (Catz631(at)aol.com)> wrote:

[quote]     This is just an update on the Paradise P-1 we have been working on. To review, the aircraft had developed a vibration at cruise rpms that could be felt thruout the aircraft in flight and on the ground. After much testing (carbs,prop pitch,tracking,etc) it was decided to pull the gearbox and send it to Lockwood for overhaul. The aircraft has less than 300 hrs since new, the torque friction test was OK albeit on the lower side compared to another Paradise of equal vintage (3years old) I personally couldn't see how it could be the box but the owner wanted to do it so. Lockwood inspected the box, said it looked fine,reshimmed it and sent it back with new belville washers. We reinstalled it and he flew it yesterday. Vibration is gone! Well, almost.There is just a hair. He has ordered and will be installing a new Kiev prop vs the square tip Warp on the aircraft. The Kiev is lighter and has been much smoother on the few Paradise aircraft we have here. Cruise speed has also increased.

   I have also removed the taper tip,nickle edge Warp on my Kitfox and have installed the Kiev. It has made a dramatic difference for my aircraft! The Kiev is very quiet and as smooth as a turbine and more importantly, I am no longer plagued with the kickback problem I was having on shutdown. I haven't realized an increase in cruise speed ,however as in the Paradise

   Please don't get me wrong, that Warp is tough as nails and I do like it but the Kiev has solved my problems.

  The Lockwood tech was not suprised that the gearbox reshim /correct propellor combo solved the problem as they have dealt with that many times before even with low time engines.

  I just relate this story because sometimes things are not what they seem. I was absolutely sure the gearbox was not a problem. Maybe the "heavier" Warp was creating more wear, weaker bellview springs, who knows?

                                                       Dick Maddux

                                                      912UL

                                                      Milton,Fl 

   	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	


[b]

_________________
The smallest miracle right in front of you is enough to make you happy....

sdemeyer

Joined: 31 Jul 2009
Posts: 45

Posted: Mon Aug 02, 2010 9:08 am Post subject: Gearbox/prop

Dick, I had exactly the same thing happen a couple of months ago on my 912. I spent weeks going through every nook and cranny to find the vibration source. Finally, I gave up and took it to the Rotax repair station in Arlington. The owner told me the vibration was probably the gearbox and like you, I was "absolutely sure" it was not. The gearbox was overhauled and re-shimmed and the vibration went away! I had about 350 hours on the gearbox.

Scott

--- On Mon, 8/2/10, Catz631(at)aol.com <Catz631(at)aol.com> wrote:

 	  Quote: 	
		  

From: Catz631(at)aol.com <Catz631(at)aol.com>

Subject: Gearbox/prop

To: rotaxengines-list(at)matronics.com

Date: Monday, August 2, 2010,  5:39 AM



   This is just an update on the Paradise P-1 we have been working on. To review, the aircraft had developed a vibration at cruise rpms that could be felt thruout the aircraft in flight and on the ground. After much testing (carbs,prop pitch,tracking,etc) it was decided to pull the gearbox and send it to Lockwood for overhaul. The aircraft has less than 300 hrs since new, the torque friction test was OK albeit on the lower side compared to another Paradise of equal vintage (3years old) I personally couldn't see how it could be the box but the owner wanted to do it so. Lockwood inspected the box, said it looked fine,reshimmed it and sent it back with new belville washers. We reinstalled it and he flew it yesterday. Vibration is gone! Well, almost.There is just a hair. He has ordered and will be installing a new Kiev prop vs the square tip Warp on the aircraft. The Kiev is lighter and has been much smoother on the few Paradise  aircraft we have here. Cruise speed has also increased.

  I have also removed the taper tip,nickle edge Warp on my Kitfox and have installed the Kiev. It has made a dramatic difference for my aircraft! The Kiev is very quiet and as smooth as a turbine and more importantly, I am no longer plagued with the kickback problem I was having on shutdown. I haven't realized an increase in cruise speed ,however as in the Paradise

  Please don't get me wrong, that Warp is tough as nails and I do like it but the Kiev has solved my problems.

  The Lockwood tech was not suprised that the gearbox reshim /correct propellor combo solved the problem as they have dealt with that many times before even with low time engines.

  I just relate this story because sometimes things are not what they seem. I was absolutely sure the gearbox was not a problem. Maybe the "heavier" Warp was creating more wear, weaker bellview springs, who knows?

                                                      Dick Maddux

                                                      912UL

                                                      Milton,Fl 

   	  Quote: 	
		  http://www.matronics.com/Navigator?RotaxEngines-Listel="nofollow" target="_blank" href="http://www.matronics.com/contribu=== 	


	
 [quote][b]

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Tue Aug 03, 2010 3:37 am Post subject: Gearbox/prop

Rick,

  Thanks for the prop balance info and Roger I will check out that balancer. I didn't balance my previous Warp but didn't think it was that bad at all until I installed the Kiev. My "old" Warp is a taper tip with nickel leading edges and had been on the plane for over 12 years. A recent gearbox overhaul, in an attempt to solve my "run-on "problems, revealed a gearbox in good condition with little to no wear. However, I was going to the Kiev anyway because of its reputed smoothness, quietness, lightness, performance and overall beauty. 4 out of 5 is not bad. I am very happy with it and no more runon(backwards) at shutdown!

  I will get the balancer for my own use and also other LSA aircraft.

                                                    Dick Maddux

                                                    912UL

                                                    Milton,Fl

  [quote][b]

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Tue Aug 03, 2010 11:24 am Post subject: Re: Gearbox/prop

Hi Dick,



I pull the entire prop and hub off. I put all the bolts back on and balance everything from the gearbox prop flange forward. I always find them out of balance. If you never try a static balance on a prop 95% of the people won't know it is really out of balance unless it shakes the whole plane. Most people think that tiny little vibration is normal and some you can't feel. Props are like our carb balance at 100 hrs. They are always out of balance until proven otherwise.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

ricklach

Joined: 20 Jun 2006
Posts: 127
Location: Kernville, Calif.

Posted: Wed Aug 04, 2010 6:14 am Post subject: Re: Gearbox/prop

Roger, or any one else for that matter, how and what do you use to add weight to balance the prop? I would think you can't remove weight but if you do how do you do that? I've balanced a lot of things but adding or removing weight on a Worp Drive prop looks like a very delicate thing.  



Rick

_________________
701Driver
N35 26.700, W118 16.743

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Wed Aug 04, 2010 6:48 am Post subject: Re: Gearbox/prop

Hi Rick,



There are a couple of ways to add weight.

 

1. Just add paint or lacquer to the prop. Now of course this depends on the prop as to what you spray on it.

2. I will quite often just add a washer on the back of one of the mounting bolts. This is the easiest and you can simply move the washer from bolt to bolt until you have a good balance and it isn't a permanent thing. Most of the time it takes a 1"-1.5" fender washer to make enough weight this close to center of mass, but still a simple effective solution.

3. depending on the spinner set up I might even use the lead wheel stick on weights.

4. If you have a back plate to a spinner you can drill a small hole and add a small screw and a few washers to the back plate.



Doing a static balance is not hard and everyone should do it. You might not think your prop needs balancing or can feel it, but you plane does. Since I have been doing some wheel testing over the last few months I also believe all tires/wheels should be balanced, too. The balancer I posted previously works well for both. There are more expensive balancers, but I thought for the money this was an excellent choice to keep cost down and affordable.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Wed Aug 04, 2010 7:41 am Post subject: Gearbox/prop

Rick, I use paint. My WD 66" three blade with straight blades needed two grams on one blade and one gram on another and it was right on. I determined the amount of imbalance by applying 1" squares of Gorilla tape until I got a balance that didn't change no matter how I oriented the prop on the balancer. Then I removed the stack of tape squares and weighed them on a precision digital scale. When I painted the prop I counted the number of coats I put on each blade (I painted the prop with the blades assembled in the hub). I made a WAG that two light coats equaled one gram so after I had all blades equaled out and fully coated I added the number of fog coats that my WAG said would do the trick. Turned out that was a good WAG. After two days of drying I checked the balance. I should say at this point that I was repainting to go from WD flat black to cherry red. Anyway, my plan was to fine tune by painting the blade tips white after the base coat of paint was well cured (a couple of months). Back on the balancer (a precision knife blade type that my A & P neighbor was nice enough to loan me) I nailed it within .2 grams, a bit less than half the spec. I figured that was good enough. I haven't gone back to repaint the tips, I'll do it when I check prop balance at next annual. 



Rick Girard



On Wed, Aug 4, 2010 at 9:14 AM, ricklach <rick(at)ravenaviation.us (rick(at)ravenaviation.us)> wrote:

[quote] --> RotaxEngines-List message posted by: "ricklach" <rick(at)ravenaviation.us (rick(at)ravenaviation.us)>

 

 Roger, or any one else for that matter, how and what do you use to add weight to balance the prop? I would think you can't remove weight but if you do how do you do that? I've balanced a lot of things but adding or removing weight on a Worp Drive prop looks like a very delicate thing. [Shocked]

  

 Rick

 

 --------

 701Driver

 N35 26.700,  W118 16.743

 

 

 

 

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ricklach

Joined: 20 Jun 2006
Posts: 127
Location: Kernville, Calif.

Posted: Thu Aug 05, 2010 7:40 am Post subject: Re: Gearbox/prop

Thank You both, Roger and Rick Girard for your very informative response's. I'll make myself a balancer tomorrow and balance the prop the day after. Today I'm going flying to establish a base line for the prop balancing effort.



Rick

_________________
701Driver
N35 26.700, W118 16.743

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