TORQUE VALUE FOR PROP BOLT

MoonlightVFR · Post by **MoonlightVFR** » Mon Jul 31, 2006 2:23 pm

What are the torque values for prop bolts on an 8 bolt 0-300 C continental engiine? inch LBS and or foot LBS?

A/C is C170B sn 26433 /N2890C

My Continential engine manual is not available to me for reference for
7-10 days.

My bolts are good with a little light rust on head which I expect AC 50
corrosion spray to stop.

Where can I purchase a set of "Spare Bolts" for the future ?

cessna170bdriver · Post by **cessna170bdriver** » Mon Jul 31, 2006 2:57 pm

MoonlightVFR wrote:What are the torque values for prop bolts on an 8 bolt 0-300 C continental engiine? inch LBS and or foot LBS?

SB96-7C regarding Torque Limits does not specifiy a torque for propeller bolts, so I used the "standard" torque for a 3/8-24 bolt called out in the same SB:

275 - 325 in. lbs
22.9 - 27.1 ft. lts

I aimed at the middle of the range and used 300 in. lbs (25 ft. lbs).

MoonlightVFR wrote:Where can I purchase a set of "Spare Bolts" for the future ?

The 170b IPC calls for AN6-H-45, but since the bolt does not need to be drilled at the threads, AN6H-45A would work fine. Hopefully George or others will pipe up if this has been superceded, or if there is a better option. AC Spruce lists these online at 3.45 ea, but going to the pdf catalog page, they're listed at $5.21 ea.

I bought my current set of prop bolts about 5 years ago and I'm fairly sure they are just drilled-head AN bolts.

Miles

Indopilot · Post by **Indopilot** » Wed Aug 02, 2006 4:36 am

If you go to the prop manufacturers web site they will list your prop model and the torque they want their props torqued to in their service information.. I look this up every time I install a prop since I can;t remember and shouldn't do it from memory anyway.

Hope that helps. Brian

swanstedt · Post by **swanstedt** » Wed Aug 02, 2006 12:36 pm

According to the Cessna 100 - Series Service Manual page 14-3 the 8-bold pattern gets torqued to 250 inch lbs. and the 6-bolt pattern gets torqued to 55 - 65 ft. lbs.

Scott

cessna170bdriver · Post by **cessna170bdriver** » Wed Aug 02, 2006 4:07 pm

Indopilot wrote:If you go to the prop manufacturers web site they will list your prop model and the torque they want their props torqued to in their service information.. I look this up every time I install a prop since I can;t remember and shouldn't do it from memory anyway. Hope that helps. Brian

Indopilot,

It had never occurred to me before to check for service bulletins on McCauley's website. http://www.mccauley.textron.com Their service bulletin 227B, Propeller Mounting Torque states that fixed pitch propeller mounting torque is to be determined by bolt size:

3/8: 30 to 25 lb.ft; 360 to 300 lb.in
7/16: 45 to 40 lb.ft; 540 to 480 lb.in
1/2: 65 to 55 lb.ft; 780 to 660 lb.in

In the text of the bulletin, they also state to refer to the aircraft maintenance manual for propeller torque. Seems to be a bit of a discrepancy here. According to the Cessna manual I'm 50 in.lb overtorqued, and according to McCauley, I'm at the bottom of the acceptable range...

Miles