What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Prop Bolt Torque Wrench Trivia

Ironflight

VAF Moderator / Line Boy
Mentor
OK, this pertains to good old fashioned Hartzell Constant Speed Props....all of you with fancy lightweight modern props can sit on the sidelines if you wish... :p

There have been a number of threads on this and other forums about how to torque the prop bolts - those captive nut/bolt things that then take a couple hours to safety wire properly. The problem is that you can't get a regular torque wrench in there, so must folks use or build some sort of extension (I really hope that not to many people pay what Hartzell asks for their special extension!). I used a short combination wrench with a series of nuts an bolts through the closed end to mount the torque wrench on (saw it on someone else's web site).

The funny thing is that when people post this solution, someone else always comes back ad says "just use a crow's-foot on your torque wrench!" Well, I tried that, and it just wouldn't work - but I know the folks that say it have, and are sincere.

SO this weekend we were reinstalling the prop on Louise's -6, and I was slowly torquing it down with my jury-rigged tool, and a neighboring A&P stopped by and says "That looks really neat, but why not just use a crow's-foot on the torque wrench?" I quickly pulled my crow's-foot out of my pocket, put it on my torque wrench, and showed him why not....it would go on the nut. At which point, he said "try my torque wrench!", and pulled out a Snap-On. Sure enough, there was the difference. The head on my Craftsman wrench is large and bulbous compared to the slimline design of the Snap-on, and that allowed the better wrench to fit. SO everyone is right - some wrenches fit, others don't - it's about the brand (or design) that you use.

(As an aside, I am doing some refresher training at work, trying to re-qualify on the Space Station Flight Director console to help those folks out when I can afford time away from Shuttle. I recently had a class on the ISS tool kit. The Shuttle tool kit is about the size of a breadbox - simple, basic, fits most of what we might have to do. The ISS tool kit is considerably beefier - since the ISS never comes home, you have to be able to fix just about anything on orbit. It's the size of a big refrigerator! The hand tools? Looks like they went through the Sap-on catalog, hit "Select All", with a quantity of "1", and placed th order. It's tool heaven....)
 
Ironflight said:
SNIP

(As an aside, I am doing some refresher training at work, trying to re-qualify on the Space Station Flight Director console to help those folks out when I can afford time away from Shuttle. I recently had a class on the ISS tool kit. The Shuttle tool kit is about the size of a breadbox - simple, basic, fits most of what we might have to do. The ISS tool kit is considerably beefier - since the ISS never comes home, you have to be able to fix just about anything on orbit. It's the size of a big refrigerator! The hand tools? Looks like they went through the Sap-on catalog, hit "Select All", with a quantity of "1", and placed th order. It's tool heaven....)

Wow, Paul, and it costs how much to heave one pound into orbit? No one here should complain about the cost of Snap-On anymore! That is one expensive refrigerator.

Back to the topic at hand, not all crow's feet are the same either. We tried to tighten a guy's O320 C/S prop here with one of my crow's feet, and the dang thing would deflect enough to try to round the nuts.

This is what I think is the cat's meow for our props, but it is not cheap:

Item 5347A24 (IIRC) plus the appropriate sized "crow foot" accessory from http://www.mcmaster.com
 
I have a Snap-On torque wrench. The head is articulated and not too big, but still wouldn't work with a crow's-foot...
 
scard said:
I have a Snap-On torque wrench. The head is articulated and not too big, but still wouldn't work with a crow's-foot...

I should have gotten the model number of the one that worked....nuts, always something more to check!
 
Wow, after seeing the Snap-On wrench price in the previous post, I retract my comment about the Sturtevant wrench being expensive (from McMaster, with interchangable heads, crows feet, etc. - see my previous post on this thread).
 
Expensive is relative.

Take a look around mechanic shops where the persons livelihood depends on their tools------------lots of SnapOn there.

The guarantee is un-beatable, and sales/service trucks making routine stops at the facility.

Very possibility overkill for our needs, but the target market is the professional mechanic.
 
Last edited:
Offset wrench

Bob Avery sells: HARTZELL-STYLE PROPELLER WRENCH

This is a copy of the Hartzel recommended wrench for about 1/10 the price and a good addition to any airplane mechanic's tool chest.
 
Chickenlips said:
Bob Avery sells: HARTZELL-STYLE PROPELLER WRENCH

This is a copy of the Hartzel recommended wrench for about 1/10 the price and a good addition to any airplane mechanic's tool chest.
But only the 3/4" used on the 360s. I asked him about a 5/8" that us little 320 drivers use. He said there wasn't enough demand to make the size I needed :).
 
Gary Bricker

Snapon sells a torque wrench for props with interchangeable head. A neighbor has the one with a 3/4 head. The heads look like a forward facing crow's foot. This would be a good item for the tool dept of most chapters to have.
 
3/4" Stubby Wrench + 5/8" Spark Plug Socket = Hartzell Prop Wrench

While looking into what I could use for a Hartzell Prop Wrench, I thought why can't I use a 3/4" Stubby wrench and then maybe hack it up and weld a 3/8" drive into the closed end of the wrench? Then while standing over my toolbox with the stubby open end wrench, it hit me, why not find something that can go into the closed end of the wrench without having to weld anything. That is where the 5/8" spark plug socket comes in. Almost all of my 3/8" drive sockets sets include this as standard equipment. So here are a few pictures of the solution instead of buying the costly Hartzell Prop Wrench.


Here are the only tools required!
File_000.jpeg



This is what the assembled wrench looks like.
File_001.jpeg



Here is the assembled Prop Torque Wrench in the inline position where you need to apply the following formula to get the correct Torque Setting based on your Desired Torque Setting.

Actual Torque Setting = (Desired Torque Setting x Torque Wrench Length) / (Torque Wrench Length + Stubby Wrench Length)
Example: My Prop manual say these Hub bolts are to be 60 - 70 ft/lbs, so I will use 65.

Actual Torque Setting = (65 x 11") / (11" + 4.5")
Answer = 46 ft/lbs if using inline method as the picture below.
File_002.jpeg



If you don't want to have to calculate the Desire Torque Setting, you can use the 3/4" Stubby Wrench and 5/8" Spark Plug Socket at 90 degrees to the Torque Wrench. This way you can use the actual 65 ft/lbs dialed in directly on the wrench.
File_003.jpeg




Thanks
Ray Doerr
RV-10 (N519RV) with 1275 hours on the the Hobbs.
 
Last edited:
I simply cut an old 3/4 inch wrench in half and welded a socket to the cut end. Took about 10 minutes to make.
 
This tool is worth every penny.....

I stumbled around and found this one day. It is very beefy...works fantastic..can be adjusted to various lengths....can use various sizes of
wrenches....simply calculate the torque value depending on the length you
have to stick out the wrench....easy peezy...I LOVE THIS TOOL:cool:

Plus since I bought it from a motorcycle website....the airplane can do wheelies:D

http://www.motionpro.com/motorcycle/partno/08-0380/
 
Back
Top