Hartzell spinner rear bulkhead install

[C-GRVT]

I am just about to install the rear bulkhead on the 7497 prop hub (attaches to four hub clamping bolts).
The Hartzell prop manual specifies the use of new (underlined) metal lock nuts -"Spinner mounting nut", part number B-3599.
Of course, the existing nuts come installed and tightened down on the prop, as delivered, and no new nuts are supplied, although everyone installing a Van's supplied prop and wishing to follow the Hartzell instructions will need four new nuts.
Anyone who knows about these props know what kind of nuts these are and where to get them, or do I go to Hartzell?
Thanks,
Bill Brooks
Ottawa, Canada
RV-6A finishing (stuck installing the prop bulkhead)

[shuttle]

Originally Posted by C-GRVT

the existing nuts come installed and tightened down on the prop

I think you can count yourself as unfortunate there Bill.
On delivery, the spinner bulkhead nuts on my 7497 were only finger tight.

[Lars]

Originally Posted by C-GRVT

I am just about to install the rear bulkhead on the 7497 prop hub (attaches to four hub clamping bolts).
The Hartzell prop manual specifies the use of new (underlined) metal lock nuts -"Spinner mounting nut", part number B-3599.
Of course, the existing nuts come installed and tightened down on the prop, as delivered, and no new nuts are supplied, although everyone installing a Van's supplied prop and wishing to follow the Hartzell instructions will need four new nuts.
Anyone who knows about these props know what kind of nuts these are and where to get them, or do I go to Hartzell?
Thanks,
Bill Brooks
Ottawa, Canada
RV-6A finishing (stuck installing the prop bulkhead)

I read the same thing and decided to use new ones since the nuts on my prop were also fully tight. Turns out that here in the US, the aviation department at McMaster-Carr sells them. I don't remember the thread size offhand, but if you look on their website and click through on "nuts", then "locknuts", then "Military Specification Flex-Top Expanding Hex Locknuts", you'll find them. Package of 5, enough to do the bulkhead bolts with a spare. Cheap enough that it seemed worth the bother to me.

[C-GRVT]

Lars,
thanks.
One of the challenges of building in Canada is "international" shipping from the U.S. Mcmaster-Carr for example won't sell to a Canadian address.
But its a lead, I will search the description.
Bill Brooks
Ottawa, Canada

[jthocker]

Lets see, on my prop and also all the rest of the guys with new Hartzell props, on our field, used the brand new nuts supplied on our props. During fitting I used castle nuts for the frequent assembly/disassembly. Once all the fitting was done, I/we used the "Brand New" nuts taken off previously and reinstalled the "brand new" nuts.

[Lars]

Originally Posted by jthocker

Lets see, on my prop and also all the rest of the guys with new Hartzell props, on our field, used the brand new nuts supplied on our props. During fitting I used castle nuts for the frequent assembly/disassembly. Once all the fitting was done, I/we used the "Brand New" nuts taken off previously and reinstalled the "brand new" nuts.

Yeah, I know, and they are probably fine in any case. I'm guessing that Hartzell, having been sued at least once, probably goes overboard on recommendations about using new hardware. The trouble is gaining the knowledge and experience to know when it actually matters. In my case, Hartzell torqued the nuts on my prop fairly tight; three felt reusable based on the TLAR principle. One was kinda loose. They were cheap to replace, so I replaced 'em. Would not doing so have caused my spinner to depart the plane? Probably not. But in my case there are no other builders with new Hartzell props on the field, for that matter builders of any kind, to turn to for advice. So, better safe than sorry.

[panhandler1956]

I have my backplate on with hardware store nuts for now, but even if they would have been torqued down I would reuse them at least once without concern - IMHO.

[C-GRVT]

goes to Jon Thocker.
See below the response from Les Doud and Kevin Ryan at Hartzell. I must say that I am really impressed by the prompt and helpful support that Hartzell provides:

.....I see your point about the manual requiring a "new" nut. It implies a new nut be used each time the spinner bulkhead is installed or removed. I don't know the intent of this instruction so I will copy this reply to Kevin Ryan in our Product Support department. He should be able to give you further guidance and supply you with new nuts if they are required.

I think the intent of the owner's manual instruction is to use new nuts that have known origin. In all cases I'm aware of, we approve of the customer using the nuts provided/installed on the prop for mounting their spinner.

I hope this helps and Kevin can provide some more information.

Les Doud
Propeller Integration Engineer
Hartzell Propeller Inc.

and from Kevin:

Dear Mr. Brooks:

We recently started torquing these nuts in assembly. Prior to this, they were only on finger tight. This caused quite a few service issues because the RTV between the hub halves wasn't under pressure in those areas, and when the nuts were installed and torqued it would cause the blade bearing grease to leak from between the hub halves. Since we began torquing these four nuts, this service problem has virtually disappeared. The wording in the manual still reflects the old assembly method. I've submitted a change to the manual to clarify this. The B-3599 nuts can be removed and re-installed many times.
If you have any additional questions, or if I can be of further assistance, please feel free to contact me at your convenience.

Regards,

Kevin M. Ryan
Product Support Representative
Hartzell Propeller Inc.

[GEM930]

This is an old post, but seems like a good place to start... The four clamping bolts referenced in this post are not long enough to install my back plate and still catch the locking part of the nut. Are these some special multimillion dollar bolt that I can only get from Hartzell or will aircraft spruce carry them?