Hartzell Spinner Cracks

[Htmlkid]

So just an FYI for everyone …. My Hartzell HC-C2YR-1BFP/7497 prop and D-5769-1(p) spinner dome was purchased on 2/2010.

The spinner dome was subject to cracking and numerous fixes and eventually a composite dome replacement was the permanent fix for this issue. Unfortunately all these years no mechanic ever caught this and it wasn’t until a piece flew off that I was aware of it and Hartzell would only replace the dome within 12 months of the service bulletin issue which has long ended.

Bottom line is if you have this prop with this spinner still in service you need to replace it before this or something worse happens to you.

[philiplane]

This usually occurs because of stress induced by tightening the screws out of sequence. Spinner screws should be tightened starting from the middle of each set of screws, and work your way outwards. 

[RobertGary1]

37 minutes ago, philiplane said:

This usually occurs because of stress induced by tightening the screws out of sequence. Spinner screws should be tightened starting from the middle of each set of screws, and work your way outwards. 

What defines "middle"?

[philiplane]

If there are five screws per segment, the third screw in would be the middle. If there are only four screws, then the second screw in is the middle. You work your way out from the middle screw, to the left, and to the right. This assumes all screws are installed and loose, and have fiber or nylon washers beneath the screw heads. The screws should not be over-tightened. 

On spinners with a forward support ring on the hub, the support ring should have a snug fit through the use of strips of plastic anti-chafe tape. If the spinner is not snug here, it will crack at the screws.

[RobertGary1]

3 hours ago, philiplane said:

If there are five screws per segment, the third screw in would be the middle. If there are only four screws, then the second screw in is the middle. You work your way out from the middle screw, to the left, and to the right. This assumes all screws are installed and loose, and have fiber or nylon washers beneath the screw heads. The screws should not be over-tightened. 

On spinners with a forward support ring on the hub, the support ring should have a snug fit through the use of strips of plastic anti-chafe tape. If the spinner is not snug here, it will crack at the screws.

Ok, so you each "segment" is separated by the blades? I have a support fixture that goes around each blades so the screws continue around the blade, not sure if that is common.

[Hank]

38 minutes ago, RobertGary1 said:

Ok, so you each "segment" is separated by the blades? I have a support fixture that goes around each blades so the screws continue around the blade, not sure if that is common.

On mine, the screws that go around each blade just hold on the piece that covers up the big slot made to slide onto the blade, so that the big pointy part and the three little curved parts become one tight assembly. The screws at the back hold the entire spinner on.

[RobertGary1]

2 hours ago, Hank said:

On mine, the screws that go around each blade just hold on the piece that covers up the big slot made to slide onto the blade, so that the big pointy part and the three little curved parts become one tight assembly. The screws at the back hold the entire spinner on.

I think it does more than cover up a hole. They are stiffeners I believe.

 

-Robert

[A64Pilot]

Also a Hartzell spinner screw is at least on the bigger props a structural screw, not a regular screw. The regular screw has threads all the way to the head and a structural screw does not. I assume our smaller props use the same screw. Use of a regular screw could from the threads contacting the spinner cause a stress riser, and of course that’s where cracks originate.

The nylon washers are also very important

That’s a real shiny spinner, it’s not chromed is it? Just asking 

Edited September 30, 2021 by A64Pilot

[carusoam]

5 hours ago, RobertGary1 said:

I think it does more than cover up a hole. They are stiffeners I believe.

 

-Robert

Robert,

If you still have the original bullet shaped spinner on your plane….

You get two filler plates that are aerodynamic aids at best…  probably just beauty pieces…   

The filler plates have a tendency to crack over the decades… from the holes

Fortunately, there isn’t any noticeable  loss when they get removed…

All the parts typically stay with the spinner… or some imbalance would show…

 

So… if the filler plates get broken… we have a couple of resources around here for that…

 

PP thoughts only… not a mechanic…

Best regards,

-a-

[wcb]

@Htmlkid I sent you a PM.  I have one if you are looking for a replacement!

[RobertGary1]

14 hours ago, carusoam said:

Robert,

If you still have the original bullet shaped spinner on your plane….

You get two filler plates that are aerodynamic aids at best…  probably just beauty pieces…   

The filler plates have a tendency to crack over the decades… from the holes

Fortunately, there isn’t any noticeable  loss when they get removed…

All the parts typically stay with the spinner… or some imbalance would show…

 

So… if the filler plates get broken… we have a couple of resources around here for that…

 

PP thoughts only… not a mechanic…

Best regards,

-a-

So if I have to original 1976 bullet spinner does that mean I'm subject to this SB or not? I feel like this spinner has worked for 45 years so don't mess with it, but I hope it doesn't sling parts everywhere too (already had an engine do that a couple years ago). I've never seen any type of data plate on the inside, unless its a lightly sketched number I've not noticed.

 

-Robert

[Guest]

The spinners that came with the newer Hartzell blended airfoil propeller were subject of an SB.  The older blunt ones were not.

Clarence