Good Vibrations?

mnewb1

mnewb1

Pre-takeoff checklist
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Jun 29, 2008
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M Newberry
I have only had my Cherokee for a few months and I have about 20 hours in it.

I was taking off this evening for a local fun flight, no problems with start, I ran it up no problem, but when I took off, there was a moderate vibration that I have not felt before. It stopped about 500 ft in the air, I decided to stay in the pattern and as I turned back for downwind, had a lesser vibration again and then smoothed out almost immediately.

After I landed, I did the run up again, no problem, took off again, no vibration no problem, flew for about 40 minutes, no return.

Something to be concerned about? Am I just jittery in my early hours with this plane?
 
Tires still spinning? I have learned to hit the brakes after a few hundred feet.
 
Shawn said:
Tires still spinning? I have learned to hit the brakes after a few hundred feet.
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^Start there. My POH says at 300 feet, Press the brakes. I get vibration from the tires spinning but it is inconsistent.
 
That would be my first guess, until the mention of it recurring on the turn to downwind. Of course, once a vibration occurs, the likelihood of a second one -real or imagined- increases exponentially.
 
iflyvfr said:
That would be my first guess, until the mention of it recurring on the turn to downwind. Of course, once a vibration occurs, the likelihood of a second one -real or imagined- increases exponentially.
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that would be a good point!
 
When do you fly next?
Interested to hear if pressing the brakes stops it.
 
SixPapaCharlie said:
When do you fly next?
Interested to hear if pressing the brakes stops it.
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Keep in mind.....

If it is the nose wheel out of balance... Hitting the brakes will NOT stop it from spinning...And the shaking will continue till the wheel stops on its own...
 
N801BH said:
Keep in mind.....

If it is the nose wheel out of balance... Hitting the brakes will NOT stop it from spinning...And the shaking will continue till the wheel stops on its own...
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However, a soft field takeoff on pavement will minimize it. Just get the nose wheel up immediately.

Would be useful for a test. Be ready for the weathervaning if there is any crosswind. It can be substantial with the nose gear off the ground, and the rudder doesn't do much at low speed.

My first thought was the mains spinning as well. You can definitely feel a shudder after lift off, in many airplanes. It's worse if you rotate late.
 
SixPapaCharlie said:
When do you fly next?
Interested to hear if pressing the brakes stops it.
Click to expand...

I was hoping to get out last night, but the Wife wanted a night out so no go!


with my schedule it will probably be late next week before I can get out. I did text my mech, but I haven't heard anything back yet.
 
This seems to happen more often in planes with wheel fairings from what I've experienced but my first thought would be the wheels as well and wouldn't be concerned.
 
I would suspect a bad sparkplug. The other plug will still fire that cylinder, but the power from that cylinder will be less and vibration will be felt. Plug failures can be intermittent. And sometimes a weak plug wont show up on the runup.

Or a mag needs looking at.

90% of engine troubles are electrical.

I doubt that the wheels are doing it. If a nosewheel spins too long, its bearings need more preloading. And that downwind leg would have to be mighty low to get the vibration going again if it were wheels.

Dan
 
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My CTSW had a *horrible* vibration after liftoff, that was cause by some out-of-round tires (not sure if I was the cause or not). I'd hit the brakes right after takeoff and it stopped instantly. I have since changed tires and it's totally gone.

Still not a bad idea to hit the brakes right after liftoff though.
 
I am going to admit this.
First few times I hit the brakes after liftoff, I had this split second reflex thought that I am going to stop the plane.

Don't act like you all haven't has that same thought :)
 
SixPapaCharlie said:
I am going to admit this.
First few times I hit the brakes after liftoff, I had this split second reflex thought that I am going to stop the plane.

Don't act like you all haven't has that same thought :)
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:rofl:

I can honestly say when I have hit the brakes in the plane after take off it has never even occurred to me the plane should stop. :no:
 
SixPapaCharlie said:
I am going to admit this.
First few times I hit the brakes after liftoff, I had this split second reflex thought that I am going to stop the plane.

Don't act like you all haven't has that same thought :)
Click to expand...

Not at all...I have a hand brake. :D
 
My 68' 140 does the same thing at times.. The wheels will spin and I will feel a vibration from them for a couple of seconds.. I always thought it was a cool sound! lol :D
 
I am still curious about this.
Have you had a chance to go up and see i the brakes stop it?
 
Have had this happen on numerous planes. In every case it was the nose wheel. More pronounced when wheel fairings were installed.
 
I had the mech look everything over, he did not find anything, I took it up Friday and a much less pronounced vibration but still there a bit, putting on brakes did not seem to make a diff, but it stopped again about 1000 ft....a bit of a windy day, that may have had something to do with it. But it certainly could be the nose wheel.
 
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