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View Full Version : Torque ? Wood prop, Continental IO-240



kitfoxJeff
06-23-2017, 04:20 AM
Hello everyone,
I bought a crashed kitfox 5 with an IO-240 in it, and rebuilt the plane in the past few months.
I purchased a new propeller from pros inc.

I was wondering if I can have some information shared about the torque settings for the prop bolts. What should I torque them to? then, how often should I re-tighted, or check them.

efwd
06-23-2017, 04:53 AM
Your going to need to let one know what prop and engine combination your using to get your answer. Congrats on nearing completion.

avidflyer
06-23-2017, 05:05 AM
Doesn't the prop manufacturer have torque info available? JImChuk

jrevens
06-23-2017, 09:12 AM
Jim's right... every propeller I've ever bought, whether wood, composite or metal has had available recommended torque values. Wood props, especially, will vary depending on type of wood, composition & other factors. That is one area you'd be very wise to avoid guessing about. Follow the manufacturer's recommendations/specifications.

kitfoxJeff
06-24-2017, 07:12 AM
Jim's right... every propeller I've ever bought, whether wood, composite or metal has had available recommended torque values. Wood props, especially, will vary depending on type of wood, composition & other factors. That is one area you'd be very wise to avoid guessing about. Follow the manufacturer's recommendations/specifications.

Thanks guys I'll contact props incorporated.

kitfoxJeff
06-25-2017, 07:15 PM
Jim's right... every propeller I've ever bought, whether wood, composite or metal has had available recommended torque values. Wood props, especially, will vary depending on type of wood, composition & other factors. That is one area you'd be very wise to avoid guessing about. Follow the manufacturer's recommendations/specifications.

I found out. Any where between 4 and 6 ft lbs.

PapuaPilot
06-25-2017, 07:44 PM
Do you have the torque sequence and is it done in increments?

jrevens
06-25-2017, 10:42 PM
I found out. Any where between 4 and 6 ft lbs.

I sure don't want to muddy the waters, but that sure sounds like a VERY low torque spec for a wood prop. Do you know what kind of wood it is made of? Hard Maple is one of the common woods used by some manufacturers. Are you using a face ("crush") plate? What size bolts?

Here are some common propeller brands in the Experimental world, and their recommended torque values for wood props, 3/8" bolts and a crush plate -

Sensenich : 15 to 19 ft. lbs.
Aymar-DeMuth : 18 ft. lbs.
Pacesetter : 25 ft. lbs.
Prince : 17.5 ft. lbs.

PapuaPilot
06-26-2017, 05:59 AM
Good point John. The torque on my Catto prop is 25 ft-lb.

jiott
06-26-2017, 09:08 AM
This sure is one area where you want to get it right! There are many stories of a prop coming off in flight.

jiott
06-26-2017, 09:09 AM
This sure is one area where you want to get it right! There are many stories of a prop coming off in flight.
Maybe that 4-6 is a metric value?

nlappos
07-09-2017, 11:45 AM
Here's what Culver Propellers says (using a backer plate) :
Torque Specifications for Propeller Bolts:
1/4” bolts . . . . . . . . . . . 132 inch pounds (+ or – 10 inch pounds)
5/16” bolts . . . . . . . . . . . 144 inch pounds (+ or – 15 inch pounds)
3/8” bolts . . . . . . . . . . . 200 inch pounds (+ or – 20 inch pounds)
7/16” bolts . . . . . . . . . . . 250 inch pounds (+ or – 25 inch pounds)
1/2” bolts . . . . . . . . . . . 300 inch pounds (+ or – 25 inch pounds)

David47
07-10-2017, 03:19 AM
Does anyone lockwire the prop bolts together ?

efwd
07-10-2017, 06:44 AM
I thought everybody did.

jiott
07-10-2017, 09:05 AM
The Whirlwind props don't use lockwire. They use Nordlock washers.

PapuaPilot
07-10-2017, 09:43 AM
Typically props are secured using safety wire. Some use the self-locking nuts, which should be replaced every time.

David47
07-11-2017, 05:09 AM
I thought everybody did.

Reason I asked the question about lock wiring of prop bolts was a friend of mine used to work with the Australian ATSB (equivalent to USA NTSB). He was investigating an accident where the aircraft lost a prop and the resulting landing involved a serious injury. Turned out the prop bolts were not positively locked in any way. They merely relied on torquing of the bolts, not even lock washers, and it was a wooden prop. Whether it had a crush plate I can't recall, but for me, it's a no brainer - some form of positive bolt retention is critical.

jiott
07-11-2017, 09:32 AM
Whirlwind allows multiple tightening cycles for their Nordlock washers, I believe it was up to 12 cycles. They are quite impressive as a locking device. There is no way they can gradually back off; it takes full torque reverse "pop" to cam up over the ridges before they will turn in reverse. As long as they have that definite "pop" they are still good to go. I have nothing against traditional lockwiring, but my whirlwind prop bolts did not come with drilled heads.

efwd
07-11-2017, 11:35 AM
Interesting. First I Googled Nordlock washer. wow, expensive by washer standards. Then I thought, "why replace inexpensive safety wire that has worked for everyone so far with such expensive washers?". I then watched www.youtube.com/watch?v=cDlmbMV9ICU. I learned why.
Eddie

kmach
07-11-2017, 04:05 PM
Nordlock washers are on the Sensenich ground adjustable prop I have , they hold tight and "snap " when undoing. A great lock washer.