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TB20 vibration

Hi Everyone!

On my recently purchased TB20 (sn 578) , I feel a low frequency vibration (almost in all flight phase) . I see on overhead panel, on the yoke. Has anybody any idea what may cause this? Prop and the engine has 25 hours total. Dyn prop balancing issue?
Thx
Zsolt

Zsolt Szüle
LHTL, Hungary

Zsoszu wrote:

Dyn prop balancing issue?

Probably.

LDZA LDVA, Croatia

What frequency? Is the frequency proportional to the engine RPM? “low frequency” is a very relative term.

The elephant is the circulation
ENVA ENOP ENMO, Norway

Also check that the spinner is on square. Have someone stand in front of the aircraft with the engine running and eyeball the pointy end of the spinner for cyclic motion…. This can happen if the spinner is not fitted snugly onto the forward bulkhead after spinner removal for the annual….the eventual result will be fatigue cracks in the spinner and backplate / bulkheads…

Last Edited by AnthonyQ at 14 Jun 09:30
YPJT, United Arab Emirates

Another thing is that the spinner is supposed to have a mark inside it, for orientation, after which somebody should have done dynamic balancing on it, and then the spinner has to go back on the same way always.

Other vibration sources are

  • baffle seals in wrong material – see e.g. this
  • metal baffles touching the cowling
  • exhaust pipe touching the cowling
  • something stiff bypassing one of the rubber engine mounts
  • a nick in the prop (FOD) – whether dressed (filed) out or not

This is worth a quick read, if only to show how hard it can be to chase this stuff around.

If your plane has had a new prop, dynamic balancing is a MUST as a matter of standard procedure – because the manufacturing tolerances are nowhere near good enough. The prop will have been statically balanced only.

However, an IO540 is not a very smooth engine

Administrator
Shoreham EGKA, United Kingdom

Just back from Straubing /EDMS/ from MT Prop. They were great and helpful. There was a small dent on the blade, they corrected it. Actually, the vibration if the engine / without the cowling was 0.05. very low. Actually a got a free visit, they did not asked anything for the measurement. On the way back to Budapest, I had vibration still but less intense. I will proceed into the direction of baffle / engine mount check. Will ask the previous maintenance company, if they changed or not anything. But as I see them, after the aircraft released….dont think if they changed the mounts.

Zsolt Szüle
LHTL, Hungary
6 Posts
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