sticky prop on a beaver

[chilly]

Hello I am currently flying an old beaver on floats and we run it at 29 and 19 in cruise. the problem is sometimes in flight it with the mp the same the prop will drop to around 1880 or so and get stuck if you try to bump it back to 1900 you can push the control right to full increase and it will not advance the prop at all... does anyone have any idea what the problem may be?
p.s. if you bring the prop control down it will decrease the rpm but it wont return to 1900 when you set the control where it normal would be.
Thanks.

[Big Pistons Forever]

Your airplane is broken. Write the snag in the Journey Log and refuse to fly it until it is fixed.

[Pratt X 3]

[sportingrifle]

On first glance it sounds possibly like a governor problem, not a prop problem. Are you running the 3 blade Hartzell, 2 blade counterweight, or 2 blade hydromatic prop?

If you are running the 2 blade counterweight, shut it down in coarse pitch and then find or make 2 blade paddles. Round up a helper and try and twist the blades from coarse to fine pitch and back. They should move smoothly without hanging up and require about 50 foot pounds of torque to accomplish this. Also wiggle the blades at the tip. They should not be loose in the hub. If this checks out you are most likely looking at a governor or plumbing problem. Don't ignore. A prop hanging up in a heavily loaded Beaver could go from being a prop problem to a flying problem!

Cheers Sportingrifle.

[chilly]

Thanks for your input, I had a feeling it was more of a governor issue or something of that nature. It is a 2 blade hamilton standard prop

[iflyforpie]

Your airplane is broken. Write the snag in the Journey Log and refuse to fly it until it is fixed.

+1

Had a customer (commercial customer, with a ~300TT pilot self-dispatching out of a remote base) who was complaining that on each of her flights that the prop kept advancing when climbing and that she had to keep on dialing back the prop knob to keep it going.

I told them the plane should be grounded right then and there... explaining the harsh reality of what happens when a prop goes to the fine pitch stops when flying by relating the story of a recovery of a 185 on floats east of Hope that basically only had time to find a clearing before going in. The problem was a nut or bolt or something that was incorrectly torqued during overhaul.

That fan is keeping you alive. Don't mess with it.