Prop Balancing Question

[A Lieberman]

Past couple of flights, found a screw that was loose on the spinner and
actually lost one in flight. A&P replaced them, and said during preflight,
check them. If they work their way loose again, need to get the prop
balanced.

Logs show no maintenance on the prop, so I am sure it's well overdue as it
has 2400 hours on it.

Today's flight, lost a screw in flight, and talked with my A&P. He is
going to arrange for a person to come out and balance the prop tomorrow.

Question is, after the balancing is done, what should I look for (if
anything) other then unusual vibrations and the like?

Is this one of those types of repairs, where I should stay in the pattern,
or is it OK to go to the practice area?

Plane is a 1976 Beech Sundowner.

Allen

[Paul kgyy]

The shop should be able to show you a before/after graph showing a much
smoother pattern after the balancing. I'd stay in the pattern for a
while if I were the first person to fly after the balancing - trying
different RPMs to make sure it's reasonably smooth at all RPMs.

[Fly]

I've been balancing props for almost 20 years.
I never heard of a instance of losing spinner screws in flight.

It is unusual, not normal. I'd be surprised a simple dynamic prop
balance will correct the problem .

Spinner screws are installed with about 10-15 lbs of torque. Not much and
they don't need much.

Something needs looking at if a spinner assembly is vibrating enough to back
out screws.

Make sure the dome, the backing plate, and the supports are fitting
properly.

Nutplates stripped?
#8 screw in #10 hole?

Next, who knows... my first guess would be the crank dampers have been
detuned and are allowing torison vibes to buzz the spinner.

Its guessing by remote control over the internet.
Get it looked at by someone savy.

Kent Felkins
Tulsa









"A Lieberman" > wrote in message
...
> Past couple of flights, found a screw that was loose on the spinner and
> actually lost one in flight. A&P replaced them, and said during
> preflight,
> check them. If they work their way loose again, need to get the prop
> balanced.
>
> Logs show no maintenance on the prop, so I am sure it's well overdue as it
> has 2400 hours on it.
>
> Today's flight, lost a screw in flight, and talked with my A&P. He is
> going to arrange for a person to come out and balance the prop tomorrow.
>
> Question is, after the balancing is done, what should I look for (if
> anything) other then unusual vibrations and the like?
>
> Is this one of those types of repairs, where I should stay in the pattern,
> or is it OK to go to the practice area?
>
> Plane is a 1976 Beech Sundowner.
>
> Allen

[A Lieberman]

On Tue, 31 Jan 2006 23:49:21 -0600, Fly wrote:

> I've been balancing props for almost 20 years.
> I never heard of a instance of losing spinner screws in flight.
>
> It is unusual, not normal. I'd be surprised a simple dynamic prop
> balance will correct the problem .

Unfortunately Fly, you are right.

Guy came out to balance the prop and when they pulled the spinner off,
found that the bulkhead behind the spinner needs to be replaced.

Then the prop can be balanced.

Almost afraid to ask how much this will be....

Allen