Jump to content

Engine shudder at liftoff


Peter T

Recommended Posts

93 J has a shudder right at lift off that lasts a second or 2. Produces full manifold pressure and RPM and runs smoothly in all other phases of operation. I seem to remember reading something about something similar here but cannot find it. 

Link to comment
Share on other sites

9 minutes ago, Peter T said:

I thought that someone had a client with a twin where one engine shuddered and it was finally remideed with a certain brand engine shock mounts.

I’d sure try ArtVandelay’s test waaay before going there!:D

  • Like 1
Link to comment
Share on other sites

2 hours ago, Peter T said:

I thought that someone had a client with a twin where one engine shuddered and it was finally remideed with a certain brand engine shock mounts.

That sounds like urban legend not reality.

Ask yourself, why an engine would vibrate at lift of? And then ask yourself why it would only last a few seconds? It is likely that what you are feeing is a wheel vibrating that was previously dampened by the ground.  If you are feeling it up front, it is likely the nose wheel but it could be the mains. If your quick on the brake, you might try a quick jab on lift off to see if that stops it.  If it does then you can alternate on the next take off to isolate the wheel. In any case, I would check all three wheels and bearings before further flight...

Edit: I see Mr. Vandelay beat me to it.

 

Oh and maybe hold off on the complete fuel system overhaul until after you've checked the obvious issues that make sense.

 

 

  • Like 1
Link to comment
Share on other sites

suppose there could be a engine/prop vibration only at takeoff, since that's one of the few times you'd have prop p-factor at high power....

Then again, you could test that theory just by doing some power-on slow flight.  Chances are, it's the wheels anyway, though...

Link to comment
Share on other sites

Do a flaps up takeoff get it up to about 85 or 90 miles an hour and then lift off and if the shudder  is worse you found your problem, and as other people said if you brake and it stops that’s your problem but we had this too and it was out of balance  tire

Link to comment
Share on other sites

3 hours ago, Shadrach said:

That sounds like urban legend not reality.

Ask yourself, why an engine would vibrate at lift of? And then ask yourself why it would only last a few seconds? It is likely that what you are feeing is a wheel vibrating that was previously dampened by the ground.  If you are feeling it up front, it is likely the nose wheel but it could be the mains. If your quick on the brake, you might try a quick jab on lift off to see if that stops it.  If it does then you can alternate on the next take off to isolate the wheel. In any case, I would check all three wheels and bearings before further flight...

Edit: I see Mr. Vandelay beat me to it.

 

Oh and maybe hold off on the complete fuel system overhaul until after you've checked the obvious issues that make sense.

 

 

I’ve read before that Twin Comanches have been known to vibrate more with Barry Mounts than with Lord Mounts, but that was in cruise flight.

Clarence

Link to comment
Share on other sites

I had a client who bought a twin commanche and it had two fresh engines, props, and new Barry mounts in it. The aircraft would resonate and shudder so bad you might think it was coming apart.  Lord mounts fixed it. 

Link to comment
Share on other sites

4 hours ago, M20Doc said:

I’ve read before that Twin Comanches have been known to vibrate more with Barry Mounts than with Lord Mounts, but that was in cruise flight.

Clarence

Perhaps that’s true, but a two second vibration upon lift off that quickly resolves does not read like a motor mount issue.  

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.