mfleming

mfleming

Well Known Member
Patron
At a 100 hrs my Hartzell CS prop had to go into the prop shop to be resealed due to slinging grease. Now the front spinner bulkhead screw holes don't line up.
The prop shop said the front dome gets torqued on and never lands exactly on the same spot as before the disassembly. They say all the new certified prop bulkheads come slotted to compensate for this.

My question for those that have run into this:
What are you doing to make the front bulkhead fit?
 
I've heard it said that new holes and nutplates can be installed, if you get lucky enough that the new orientation is offset enough. If not, you might get stuck building a new front bulkhead.
 
mfleming said:
At a 100 hrs my Hartzell CS prop had to go into the prop shop to be resealed due to slinging grease. Now the front spinner bulkhead screw holes don't line up.
The prop shop said the front dome gets torqued on and never lands exactly on the same spot as before the disassembly. They say all the new certified prop bulkheads come slotted to compensate for this.

My question for those that have run into this:
What are you doing to make the front bulkhead fit?
Click to expand...
Buy a new bulkhead, redrill and install new nutplates.
 
Slot the 4 holes. There was a kitplanes article a couple of months back on how to do this.
 
rocketbob said:
Buy a new bulkhead, redrill and install new nutplates.
Click to expand...
If they are not too far off, you can slot the front four bulkhead screws hokes, the screws that attach it to the hub. A good example is in Vic Syracuse “how to set CS low pitch stop” video. The Hartzell prop example shows up there.
Mine were off about a quarter inch. Got the old divider out and drew an arc between the bulkhead mounting screws, drilled new holes, and took a round file to clean up the slot. It may only be good until the next rebuild, then I might be doing what Bob suggests. Also, if you’re too far off, remake that bulkhead as recommended by Bob.
 
bjdecker said:
Slot the 4 holes. There was a kitplanes article a couple of months back on how to do this.
Click to expand...
And here you go….

www.kitplanes.com

Spinner Bulkhead Clocking - KITPLANES

Spinner woes were the topic of midsummer musings on Van’s Air Force this year. Specifically, Bill from Virginia commented how, after getting his Hartzell prop hub back from an eddy current inspection (ECI) and installation of new seals, the spinner mounting holes on the S-603 forward bulkhead no...
www.kitplanes.com www.kitplanes.com
 
georgemohr said:
I've heard it said that new holes and nutplates can be installed, if you get lucky enough that the new orientation is offset enough. If not, you might get stuck building a new front bulkhead.
Click to expand...
The four holes that hold the spinner on don't have nut plates and I'm off about a half of inch.
Ironflight said:
And here you go….

www.kitplanes.com

Spinner Bulkhead Clocking - KITPLANES

Spinner woes were the topic of midsummer musings on Van’s Air Force this year. Specifically, Bill from Virginia commented how, after getting his Hartzell prop hub back from an eddy current inspection (ECI) and installation of new seals, the spinner mounting holes on the S-603 forward bulkhead no...
www.kitplanes.com www.kitplanes.com
Click to expand...

That's a great article but I don't have access to a milling machine and I'm not a machinist.
EDIT: After re-reading, my response sounded a little abrupt. I appreciated the link and ended up using this info to guide my local machine shop!


My holes are about ½" off. I think I can just drill new holes for mounting to the prop dome ( leave the outer edge holes with the nut plates alone) but haven't figured out how to precisely locate the new hole location. I could cleco the forward bulkhead to the spinner and then install the spinner but then how to mark the new hole location. Maybe if I had something to paint on the dome so the it would leave a mark on the forward backplate!? Not sure if that would be precise enough.

Any suggestions are welcome.
 
Last edited:
georgemohr said:
I've heard it said that new holes and nutplates can be installed, if you get lucky enough that the new orientation is offset enough. If not, you might get stuck building a new front bulkhead.
Click to expand...
S-603 bulkheads are predrilled for the dome mounting holes as well as the spinner holes. So it would require a new spinner, not a new bulkhead.
 
You don't need to stay in a Holiday Inn to do this.

Remove front bulkhead from dome
Use a circle template to mark two circles one on the inside of the 4 holes, the other on the outside.
Determine which way you need to rotate the front bulkhead
(optional) Do a little trig to determine the location of existing holes that the new holes need to be.
(optional) Eyeball & guess where a new set of holes should be, for 1/2" I'd swag that the new holes are going to be 1/8" - 3/16 away.
Mark 4 center lines for the new holes, on the bulkhead, 90° apart, centered on the low pitch bolt/nut hole.
Mark 4 new holes in between the two circles
Drill new holes to #21, Check Alignment within the two circles
Drill holes to #12.
Dremel out the materiel between the new holes and the original holes and stay in between the two circles marked in step 1
Deburr new holes and slots
Install two bolts, washers - just tight enough to hold the bulkhead in place but allow it to be rotated.
Install spinner and adjust front bulkhead position using an awl, or pick.
Remove spinner
Install remaining two bolts and washers
Tighten all 4 bolts
Safety wire all 4 bolts
Install Spinner
Go Fly

Use a drill press to keep the holes square and true to the bulkhead, and hopefully round -- assuming your DP has as little run-out as possible; unlike your Ryobi/Dewalt/Makita drill...
 
You must log in or register to reply here.