Removing / Reinstalling Hartzell

Can anyone walk me through the best way to remove a Hartzell from my -7A, in order to change the Alt belt? I have to switch to a shorter belt to avoid (more) rubbing on my lower cowl. My only experience is with fixed-pitch props, I bought this CS-equipped -7A flying. So tackling this 40-lb oil-filled beast is a bit intimidating.

The removal instructions in the Hartzell manual are .. well .. not overly illustrative. Paraphrasing a bit, but basically "sling prop, remove prop".

And I have been warned about some 'roll-pins' through the bolts, but still do not fully understand that arrangement.

DR posted some photos of his gasket change last week where they appeared to remove the prop without even removing the spinner. That made it look pretty straightforward. Any help?

Thanks!
Matt

Prop rem

Fairly simple. The roll pins that hold the nuts on stay in place. The bolt and nut back out in one piece. The roll pin has the safety wire thru them. Note the way the wire is and them remove the wire. Back the bolt and nuts combo out each one as far as you can then go the the next and as you get them all backed out work the prop off. Put a piece of cardboard or something and a pan under the prop flange to catch the oil that might come out. Reinstall the same way. You will need to retorque the bolts and reinstall the safety wire. I have not tried to remove with the spinner in place but I think you can. I would take it off to keep from damaging it when I was handling the prop.

The roll pins stay in place - you don't need or want to remove them.

The only real challenge removing the prop is that you have can only turn the bolts out a little bit at a time and you have to unscrew then evenly. So a 1 or 2 turns on one bolt, then 1 or 2 turns on the next bolt, etc., etc.

If you don't do them evenly, the shaft gets off-center and won't move. Having a sling to support the weight of the prop helps but you don't want to lift the prop because the shaft will bind up. When you get near the end, be careful not to damage the O-ring.

Putting the prop back on is a little more challenging. Getting the shaft lined up and getting the bolts started can be a bit frustrating - those first couple of threads are the most difficult. Once you get them started, go slow so that the shaft stays centered.

Once you break the bolts loose, you should be able to do most of the un-screwing by hand or with VERY little force if you use a wrench. If you need to use much force there's a good chance that the shaft is not coming out straight. The same goes for installing the bolts, you should be able to do it mostly by hand or minimal force with a wrench.

Prop install

Be sure to mark the prop to hub location with a marker so you can reinstall with proper clocking. Some of the collets are different sized and must go back the same or 180 degrees.

use a cherry picker and a couple v belts. job is a piece of cake. oh and don't forget the special tool for torqueing the bolts, i think you can get one at avery tool.

prop R/R

It also helps to pull a plug from each cylinder to relieve compression. Its easier to rotate the prop as you loosen the bolts.

Hartzell Removal/Reinstall

Don't forget to use a new O-ring when re-installing the prop.

Mitch
RV4 flying

Thanks everyone for the good advice. I will probably tackle it this weekend, so hopefully on Monday you will not be reading an epic writeup about a prop change gone horribly wrong!

Matt

Safety Wire Tool is really handy

This makes twisting up the safety wire a lot easier as the bolts tend to be at odd angles after torquing making the use of a standard wire twister more difficult.
http://www.aircraftspruce.com/catalog/topages/wiretwisters3.php

reinstalling hartzell cs prop

You have company in this boat Matt! I pulled mine earlier this week to swap the ring gear / pulley and install a new alternator belt. I have a pic of the studs if you want to see what you are getting into before you start wrenching; PM me if so.

I am waiting on parts from Hartzell to replace the castle nuts and pins. For some reason they specify that the nuts are loctited with 695 before they are installed, then the spring pin is installed, they are including some of that as well. Be careful you don't damage the studs, the 7/16-20 studs for my O320 are $25 each.

> i think you can get one at avery tool.

Avery sells the 3/4" one for the O360. If you have an O320 you will need a 5/8".

Phil