Noticeable vibration at 200+ hours 912iS Sport

by Paul Hamilton in 912iS Technical Questions 9 years ago

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Re: Noticeable vibration at 200+ hours 912iS Sport

by Richard Boslaugh » 6 years ago

Richard Boslaugh

9 122 84

Check the magnetic plug often. Metal above the Rotax limit is BAD. The you get to do the Rotax " flush the oil system procedure" including new oil cooler.

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Re: Noticeable vibration at 200+ hours 912iS Sport

by Jim Flock » 6 years ago

Jim Flock

13 172 189

Not too bad of a vibration, but it was noticeable. I'm only 20 hours past a fresh annual, but I will double check all of the above tomorrow. Thanks for the input.

Aviation Real Estate Specialist & iRMT

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Re: Noticeable vibration at 200+ hours 912iS Sport

by Roger Lee » 6 years ago

Roger Lee

125 5.12k 4.52k

I'm not accusing anybody, but a mechanic could have overlooked something. Now you need to do a good diagnostic check for vibration causes.

I just had a 912iS engine plane show up for my class. It was the first flight since the annual. The tail pipe fell off, the hot exhaust melted the coolant bottle and damaged the fire wall.
Then I did a walk around and found 8 other things the annual mechanic didn't do that were glaring enough I saw them on just a walk around.

I'm never going to understand why some mechanics refuse to use a checklist for the engine and fuselage. Saying I didn't know where to get a manual, service bulletins or know what to do on a Rotax just means you probably shouldn't have touched it.
1-2 Rotax classes can be gold for information and prevent mechanic induced damage.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Noticeable vibration at 200+ hours 912iS Sport

by Peter Collins » 6 years ago

Peter Collins

1 9 0

My plane has vibration while descending in the approximate rev range 4000-4800. This has been present for about a year, maybe more. First ran the engine April 2014, now at 430 hours. Oil analysis and mag plug are clean. I pretty much ignore it and or close the throttle further. Not present with the engine under load.
Just my two cents.

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Re: Noticeable vibration at 200+ hours 912iS Sport

by Genival Pacheco » 6 years ago

Genival Pacheco

4 87 135

Roger wrote

"Hi Jim,
I kind of depends on how bad the vibration was and if you have ruled out all the factors on the plane that can cause vibration.
Common causes;
Tire out of balance
elevator loose
prop blades not at the same pitch
prop out of track
loose wheel pants
prop needs dynamic balance
gearbox needs reshimming "

I´m not an expert but should consider including the verification of the rubber lords of the engine mount too.
They are always submitted to stress, even when the plane is not flying (most of the time) due to the gravity forces the upper rear and the bottom front ones are squeezed, the opposite occurs when flying.
This plus the aging effects cause their deformation and lose of flexibility that can cause vibrations normally absorbed by them to be transferred to the plane structure. So, the age of the plane is more important than number of hours flied.

I would like to know Roger´s experience on that.

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Noticeable vibration at 200+ hours 912iS Sport

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