Thorp Air Command - T18.net

Has anyone used the Hartzell hub HC-C2YK-1BF with F7666A-4 blades on their aircraft. In particular the S 18.
I have a chance to purchase one off a RV4 with an O-360 at a good price.
Trying to find out if it is suitable.
I have also asked Hartzell.

Please let us know what Hartzell has to say.

According to my manual. That prop will work. The only difference in part number from mine, is the last digit of the hub. Mine is an “L”, where this is a “K”. My manual says that means it has 1/2” studs as opposed to my 7/16”. Only difference. This is a stronger set up. I’m running a 200hp IO-320 B1A.
You should be good to go.
Cubes

By the way, the blades are Thorp standard.
Cubes

I haven't heard from Hartzell.

Cubes, Does it still use the prop extension with this prop and still ok for basic aerobatics

I have a 2” extension on mine. That is the long hub. So it depends on your cowl if you need an extension. I got mine from Saber. Great folks. They have them in 1/2” increments.
Yes, basic aerobatics are ok with the extension.
Cubes

Hey, I just received a reply from Hartzell re my request above.
Interesting info
Thank you for contacting Hartzell.
After consulting with our engineering/technical team below is the feedback we can offer;
It is our assumption that the customer has found a used propeller and would like to know if it would work. There are likely two differences that this customer is observing with respect to the hub of the subject propeller and that listed in the App Guide; the flange (K vs R) and the extension (C vs F).

1) Flange

a. An R flange propeller can be bolted onto a K flange engine, but a K flange propeller cannot be bolted to an R flange engine

i. An R flange engine has 1 flush engine flange drive bushing, a K flange engine has two flush bushings

1. See also Lycoming Service Instruction No 1098, latest revision, for drive bushing configurations for specific engine models.

ii. For experimental applications, this may not be strictly true; at some point we started manufacturing hubs in only the R configuration but marking them differently based on application/installation. So later model K hubs could bolt onto an R flange. In the case of a used propeller, it will depend on the particular hub model.

2) Extension

a. The F extension, typically used on the T-18, is 3.000” longer than the C hub.

i. Assuming the S-18 uses the same cowling as the T-18, using the C hub will move the propeller much closer to the firewall and require changes to the cowling. This is likely undesirable.



Another consideration, again assuming this is a used propeller, may be AD 2009-22-03 (see also Hartzell service bulletins HC-SB-61-269, HC-SB-61-323, and HC-SB-61-227) https://hartzellprop.com/services/produ ... documents/

qualifying early model two blade compact hubs are subject to a recurring eddy current inspection or hub replacement.



Another link to our website that you might find helpful is to our new Information Manual for Experimental Aircraft, Manual 193. https://hartzellprop.com/EXP-AIRCRAFT/M ... Vol-01.pdf



Finally if you are considering purchasing a new propeller, we would recommend the F7497-2 blade rather than the F7666A-4 as the newer design performs and looks better.

thats great info. thanks for sharing.

Reminder that I am a Hartzell dealer. I can get you better prices than Vans.
Cubes