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Tail pipe vibration

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Tail pipe vibration during high power run.i change eng rear mount,check upper mount & lower mount torque.also change tail pipe & torque check.blade angle ok.others parameter ok. please anyone can help

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If you see it vibrate it is low frequency, either the AC Generator rotor unbalanced (replace and retry) or your torquemeter is unbalanced.

Rgds

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Have you tried balancing the prop? A prop balance won't do much for helping but it's a good place to start.

Check 5th and 10th to see if the compressor is shifting, the truss mounts are good to look at too, I have found a few cracks in them in the past...

A sig run will narrow it down for you if you have the equipment.

Good luck

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Ask'em what #1 and #4 are doing ;)

Was a bit of a joke. I figure if you can't see the outboard motors, and they make it out ok, then tailpipe vibes are a bit of a comfort item to look at. Here's what I got for a vibe.

If the vibe is in the tailpipe only, and not in the throttle or condition lever:

Check tailpipe for proper installation

Inspect front engine mounts (i'd just change them and be done with it. Sometimes the inspection lies.)

Inspect rear engine mount (already changed it, right?)

Borescope turbine (-15 engines can throw a rotor blade and you wouldn't be able to tell otherwise)

If no defects were found, then the tailpipe vibe is within limits, and I dare anyone to try to create a limit with a ruler.

If the tailpipe vibe is accompanied with a throttle or condition lever vibe, then this is what I got:

Perform a propeller loose blade inspection

Perform a propeller blade tracking inspection

Inspect prop afterbody, torque retainer assembly, and front spinner for loose or damaged components

Check propeller hub nut for proper torque (replace RGB if out of limits)

Check prop shaft vertical movement and end-play

Check rear engine mount (already changed)

Check prop balance

If no defects are found, replace propeller

These are only recommendations, of course. You can complete them in any order. Checking the wing truss mounts like Ben said couldn't hurt, as well as checking the engine sloping longerons and tie struts as well.

You should also look at the maintenance history. If either the engine or propeller have been changed just before the problem started, suspect shipping damage or improper installation of either the engine or propeller or other major structural components.

Sometimes, a throttle vibe is normal, and a tailpipe vibe is normal, it's your call. Just pretend like you are going to be flying on the plane and make sure you look at anything that would make you want to land as soon as possible.

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we had same snag on our aircraft . we have changed the prop and it was ok .the prop i think out of balance

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I have found that the tailpipe vibes that I encounter are high freq. The lord mounts and prop balancing are low freq. I'd throw the chadwick on the RGB/Compressor and do a torquemeter runout.

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One thing you can try is hooking up the vibration kit and see if the vibs of items are within the limits of the books. you could have something loose in the turbine causing the vibration.

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Our C130H also has same problem and we have been battling to solve the problem. It's still there .....

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I thought this problem was resolved after we replaced the engine mounts (upper and lower)? Confirm please. 

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