The International Cessna^® 170 Association

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 ?

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 Hopefully George or others will pipe up if this has been superceded, or if there is a better option.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

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

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

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