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motoadve
Joined: 23 Apr 2009 Posts: 123 Location: Seattle
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Posted: Mon Jun 17, 2019 12:54 pm Post subject: What is the cylinder torque value for the nuts at the base.? |
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Had a big oil leak, too big to keep flying, used some dye, and it showed it was coming from the base of cyl #4 , we checked tightness of the nuts and are loose.
Glad I did not ignored this oil leak.
Does anyone know the torque value needed for the nuts at the base of the cylinder?
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_________________ www.Backcountry182.com
Cessna 182 P
CJ -6 |
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draftsjust417(at)gmail.co Guest
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Posted: Tue Jun 18, 2019 4:23 am Post subject: What is the cylinder torque value for the nuts at the base.? |
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Very good info to eavesdrop on...
What sort of material is best for stud lubrication during torquing?
These paper washers/gaskets are avail new?
Thanks - again, good info that I'll file away---
Justin
N280NC
On Tue, Jun 18, 2019 at 9:04 AM Walter Lannon <wlannon(at)shaw.ca (wlannon(at)shaw.ca)> wrote:
Quote: | This is actually a very serious problem, with the HS6A engine in particularly.
The HS6A is unique to the series in that the crankcase is shot-peened in the cylinder mounting flange area. This process is used to inhibit crack development in highly stressed areas by effectively increasing the surface area.
Strangely enough the process is not used on the M14P crankcase even though the operational temperature and stresses are, in all probability, considerably
higher. This leads one to suspect that the Chinese alum. alloy manufacturing and heat treating processes may leave something to be desired.
A few years ago a gentleman from Namibia posted a photo of a cracked HS6A crankcase where the crack surfaces were displaced from each other by something like 10 mm. A sure sign of enormous internal stress relieved by the crack. Hopefully that was a one-time occurrence.
In any case shot peening is used and with it comes a new problem.
The cylinder hold down studs are possibly the highest cyclically loaded threaded fasteners on the engine. They need to be stretched on installation to a point within their elastic limit where the operational tensile loading is absorbed without further stretching. Torqueing is a quick and dirty method of establishing that point.
By design shot peening produces a rough surface. Whether too rough for the seating surface of the cylinder flange I don’t, at this point, really know though I suspect not. The factory obviously is concerned and “corrects” this with a paper shim. This of course over time disintegrates leaving you with a loose cylinder and possibly studs stretched beyond the elastic limit, cracked or broken and a cylinder about to depart.
Notes on torque: The factory wrench for this job, Chinese or Russian, provides absolutely no means to measure the torque value. I weld a nut in the appropriate location. See attached pic.
I use a LUBRICATED 300 to 320 in./lb. torque.
Walt
From: A. Dennis Savarese (dsavarese0812(at)bellsouth.net)
Sent: Monday, June 17, 2019 2:20 PM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: What is the cylinder torque value for the nuts at the base.?
304-330 in/lbs or 25-28 ft/lbs.
Dennis
On Monday, June 17, 2019, 4:56:50 PM EDT, motoadve <motoadve(at)racsa.co.cr (motoadve(at)racsa.co.cr)> wrote:
--> Yak-List message posted by: "motoadve" <motoadve(at)racsa.co.cr (motoadve(at)racsa.co.cr)>
Had a big oil leak, too big to keep flying, used some dye, and it showed it was coming from the base of cyl #4 , we checked tightness of the nuts and are loose.
Glad I did not ignored this oil leak.
Does anyone know the torque value needed for the nuts at the base of the cylinder?
--------
www.Backcountry182.com
Cessna 182 P
CJ -6
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