Buzzing Strut

[Springloaded]

Well just landed I think I found my problem. Is this happened to any other planes.Seems like a real safety issue!

[Pete D]

This SB addresses that issue:

http://www.cubcrafters.com/pdfs/sc/sb00016.pdf

Pete D

[Springloaded]

Pete
My plane was delivered 12/10 after service bulletin and has s.s. ones.So it suppose to be the NEW improved ones and there is no way to see if it is cracked or fatigued on bolt inside the strut.Which is were mine is broke. So that service bulletin is useless for this problem unless you want us to diassemble our plane for preflight.I wipe my leading edges every time after flying so I will know if it brakes.I have a call in to Jason to see how to get this taken care of.
Chuck

[Pete D]

Ok, Jason should be able to take care of you. I guess I don't know exactly which S/N aircraft you have. I'll let Jason handle it from here.

Pete D.

[Springloaded]

Pete
Sorry got the dates wrong mine was delivered 2/10 #108 but it does have the stainless ones on it
Chuck.

[couleeone]

chuck it happened to me a couple of years ago which caused the bulletin. Eas fix with larger size brackets...no prblems since replacement. preflight by shaking the jury struts.

keep having fun and the edge of flight for the S2 is way out there...its an amazing and fun airplane!

Geo

[turbopilot]

I noticed on my video with the camera on the strut there is a buzzing. It seems to be the aileron cable vibrating in its bushings. Is there any problem with that?

Same issue noted in the audio on my Carbon Cub. It seems to be related to angle of attack rather than RPM.

[Clay Hammond]

Turbulators added to the top side of the strut reduced the vibration dramatically on an aircraft we had in dad's shop, leading one to believe that AoA and aerodynamics of the strut play a big part in the vibration of the aileron cable. I would see it come and go with RPM change, but I believe this ties back to the Angle of Attack directly. It was an extreme case and after application of the turbulators I could do dives to Vne and the vibration was minimal where beforehand it was excessive. If you have a buzzing/vibrating aileron cable consider trying something to breakup the airflow over/under the strut. Turbulators or low profile VG's, even a length of thicker welding rod taped span-wise on the strut might make a difference. You'll have to experiment and see what works for you. I'll be swinging through Aircraft Spruce East this afternoon and will check on the name of those turbulators (don't have a catalog in front of me).

If you think about it, the aerodynamics of the strut are different than the other Cubs. Whereas they had/have a true teardrop shape, the SPORT CUB/Carbon Cubs have that flat area running the length of each strut. Its my own personal shade tree engineer/aerodynamicist opinion that this change in airflow over the strut causes the cable to vibrate. And that a variance from plane to plane of AoA of the strut in relation to the rest of the airplane cause some to buzz and some not. Rack it up possibly to these products still being handmade that some do better than others. It could be that the most minute change in incidence of the strut can make or break the buzzing issue. My opinion only.

[reileyr]

For standard Piper struts, a buzzing control cable can be made quiet by tweaking the upper fairlead fitting to move the control cable into the strut slipstream. With the control cable well place behind the strut (no vibration), much of the aileron control friction can be eliminated with a slight reduction in control cable tension. I realize this is not to CC 45# spec so I'm only mentioning it in passing, but a plane with light ailerons is much nicer to fly and less tiring, especially in rough air.

[Dan L]

I see it on almost every flight in my Carbon Cub EX. Tightening the cable seemed to help for a while but it comes back. It seems to me that putting one more of the little black plastic fairleads into the mix and closing the spacing between fairleads would cure the problem. But that would have to be done when the cable is made.

I also had one of the front jury strut fittings break after 20 hours. Mitch asked if I had the little plastic bushing installed between the lower jury struts and the bracket. I didn't. He sent a new bracket and four bushings and that took care of it. He explained that there needed to be an isolation point to dampen the vibrations.