Does Our Beloved Heli God Father.....

Discussion in 'The Chat Room' started by Mark Mickels, Aug 24, 2014.

By Mark Mickels on Aug 24, 2014 at 6:13 AM
  1. Mark Mickels

    Mark Mickels Well-Known Member

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    offer vibration pardons? I'm stuck in vibration purgatory at the moment with my T-Rex 500. The bird has never been crashed and suddenly there is a vibration issue. I put on new tail blades, new tail box and blade grips, took the head apart, took the motor apart and checked the bearings, replaced the gears and the bearings in the boom box. The thing is still vibing, and I really could use a little divine intervention at this point. HGF, I'm about ready to throw it at the wall! I could have built two new kits in the time I've spent tracking down where the vibes are coming from!
     

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Discussion in 'The Chat Room' started by Mark Mickels, Aug 24, 2014.

    1. HeliGod Father

      HeliGod Father Administrator Staff Member

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      I am sorry to hear of your distress @Mark Mickels but I think i speak for everyone when I say that we have all been there before. Usually when i have vibes i go through a series of eliminations.

      I first start by removing the head and tail assembly leaving only the main shaft and tail shaft protruding.

      Clamp the model down and spool it up FAST v. Look at your vibe analyzer if you have one or place your hand on the boom.
      Is the vibration there? If it is separate the tail assembly from the body - spool again. Check for the vibes once more by holding the body. If no vibes its probably your torque tube.

      If at this point you do not have any vibes, put your boom back on.

      Spool the helicopter again. Take hold of a screwdriver, position it perpendicular to the tail shaft and lightly touch the end with the screwdriver while it is spinning flat chat (be carefull). If you hear a ticking noise you know your tail shaft is slightly bend or the bearings are possibly damaged. Do the same for the main shaft again with no head or links attached. It should feel as smooth as butter with very light pressure.

      If you have vibes and you do not have a vibe anlalyser, watch the swash plate when you spool. If you have vibes the swash will usually tilt and lean to the side after 10 seconds or so. At this point you have either found the fault or it is to do with the head and tail assembly.

      First assemble the rotor hub onto the tail and attach the tail blades. Make sure the model is clamped firmly down. Spool the heli once more. Watch the swash plate - if it has vibes it will tilt or behave erratically.

      If the vibes are present at this point disassemble the rotor hub and check that the assembly is correct. Check every washer, bearing etc because something would be throwing it out of center if there are vibes -

      If no vibes then move on to the head and do the same. Be VERY CAREFULL Now as it will have main blades on it. Usually I never have to do this last part because if everything else is ok it must be in the head assembly (IE i have put an extra spacer on the feather shaft during the head assembly or something else silly).

      This method has helped me eliminate vibes in every case so far.

      Also the above is assuming that all your blades are balanced and not damaged.

      Hope this helps,.
       
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    2. Mark Mickels

      Mark Mickels Well-Known Member

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      My beloved Heli God Father, I have done as you ask and the vibes are definitely tail related. The torque tube assembly and the tail boom are the only two remaining items that have not been inspected with precision instruments. I have that capability at my work. I can check them both to see if they are bent. I'll replace the TT assembly tomorrow and the tail boom if need be. This just get's to me because the bird has never taken a "dirt nap".
       
    3. HeliGod Father

      HeliGod Father Administrator Staff Member

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      Good luck and keep us informed. Vibes can be the most frustrating element to track down at times.
       
    4. Mark Mickels

      Mark Mickels Well-Known Member

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      As I am now learning unfortunately!
       
    5. Mark Mickels

      Mark Mickels Well-Known Member

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      I changed out the TT and bearing, but it didn't make any difference. I put a friends tail box on and everything was fine. You can see my tail blades come out of "plane" when the vibrations occur. These are the pro blade grips, and my friend said he had nothing but problems when he tried using them.
       
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    6. simon

      simon Well-Known Member

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      Good find, another useful tip in hunting the demon Vibration
      Simon
       
    7. Mark Mickels

      Mark Mickels Well-Known Member

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      I found the problem! The boom was bent ever so slightly. I put a new boom on and voila, the vibe readings are down to 479. How the heck the boom got bent is another mystery.
       
    8. HeliGod Father

      HeliGod Father Administrator Staff Member

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      That is simply divine! Now there is an upside to this. A) the mysterious vibes which can elude us always have a logical conclusion. By keeping cool and using a process of elimination you can break it down B) You now have many spares C) Each type of model has its own quirk. You have discovered a major one for the torque tube. Quite simply a bent boom will cause torque tube vibrations! Well done!
       
    9. Mark Mickels

      Mark Mickels Well-Known Member

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      Thank you father, but I must confess to using more than a bit of blue language during this process of elimination.
       
    10. HeliGod Father

      HeliGod Father Administrator Staff Member

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      Vibrations have caused even the most experienced heli mechanic to their knees at one time or another. Always use the process of elimination on any new model you acquire.. Great work!
       
    11. Mark Mickels

      Mark Mickels Well-Known Member

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      I flew the 500 today and it went perfectly! Looks like I have 3 birds to fly again.
       
    12. smakmeharder

      smakmeharder Administrator

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      Its a nice feeling to have. When one of my fleet is sick, i look at my entire life differently
       
    13. Stuart

      Stuart Active Member

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      3 birds to fly ..... think you need to donate one to @BeLoWseaLeVeL.... Lol...
       
    14. Mark Mickels

      Mark Mickels Well-Known Member

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      Yep, it's like having a sick child, and it makes you not want to put the other kids in "danger".
       
    15. Manyc

      Manyc Well-Known Member

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      I think he has enough heli's... somehow...
       

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