New style "threaded trim pin" failure

[Jasonrs]

That is correct. .5" of thread then about .75" of smaller smooth pin that just sticks in cross shaft. Only .5" of thread that is load bearing.

So replacement of that pin with a bolt from lowes doesn't seem right to me....would a bolt even do tbe job of that pin without the threadless reduced diameter at the end??

[smallykiller]

Word on the street is 5/16-24 x1/2 stainless bolt with two threads shaved off end fit. It's not ideal but when the part is back ordered for a month it allows one to still fish.

[Blue Steel]

MikesExpress and I were talking about this last night. Wonder if aircraft safety wire would work?

[fishnfireman]

MikesExpress and I were talking about this last night. Wonder if aircraft safety wire would work?

[smallykiller]

If I ran that motor, I'd safety wire it, no question.

[djb750]

I think the safety wire is a good call.
where would you secure the other end of the safety wire? Around the main post just below the bolt head?

[JAZII]

right around the cylinder rod end

I think the safety wire is a good call.
where would you secure the other end of the safety wire? Around the main post just below the bolt head?

[djb750]

right around the cylinder rod end

That's what I was thinking. I made a rudimentary sketch below from the image in the other post:

[thommo59]

My cable tie technique has worked well for me and takes 30 seconds for peace of mind

[Jasonrs]

My cable tie technique has worked well for me and takes 30 seconds for peace of mind

Can you get a pic of this?

[thommo59]

Can you get a pic of this?

I can email or send to your cell but can’t seem to get pics on here

[thommo59]

2ABFB8D0-F3E8-4DC5-A687-DD8041C10ECA.jpegED715C77-4214-426D-AA82-BAFA8D15C827.jpegL
Let’s see if these pics worked

[Jasonrs]

I can se em here, thx!

[Brewerbass]

If those tyraps are staying the safety wire idea will work good. Used to do lots of safety wiring on small cessnas, not that hard and very effective

[mikesxpress]

Joseph still experienced the bolt backing out even after applying Lock-Tite. Without actually safety wiring the bolt head (aircraft format) it's can still back out with the tie wraps as nothing is keeping it from turning. Normal aircraft safety wiring format could be modified to work here if:
1. The head thickness is substantial enough to allow for a drilled hole.
2. You have an adequate location to secure the safety wire where it will result in constant tension against the bolt.

Example for multiple propeller bolts.

[thommo59]

Why the cable tie works and there are many methods to create bolt locking devices, is it’s simple, takes 30 seconds, you don’t remove or disturb the bolt and it simply can’t fall out and be lost, causing the failures currently being reported.
It works fine for me and if I were at a ramp, and had 3 day tourney or a long run ahead, a cable tie will work for you.
Do whatever you think works for you, this works for me

[angleiron]

So to remove this bolt to add a new one with a lock washer does the motor have to be supported to relieve the tension on the bolt? My engine with just a hair over 10 hours was backed out 1 full turn, and when I tried to loosen it even further I could feel resistance which leads me to believe the weight has to be taken off or minimized so the bolt can come out freely?

[JAZII]

It does not have to be supported to do this. I ALWAYS SUPPORT IT JUST FOR SAFETY REASONS!
With the pin loose or out, DO NOT USE TRIM, the cross shaft is indexed to the pin with just a dimple in the cross shaft.

So to remove this bolt to add a new one with a lock washer does the motor have to be supported to relieve the tension on the bolt? My engine with just a hair over 10 hours was backed out 1 full turn, and when I tried to loosen it even further I could feel resistance which leads me to believe the weight has to be taken off or minimized so the bolt can come out freely?

[EuropeanAM]

I tried but Don's parts look up is blocked on my computer and phone for "not secure site"

That's simply because it is not an "https" site, as there is no financial or personal information stored there. Same thing happens with BBC on my browser.

[EuropeanAM]

Way to much force in multiple direction on two independent pieces with maybe 6-8 fine threads.

I have never heard of a tri-lobe pin failure that had not been worked on. I'm sure it's one of those one time use type of deals.

I do know when this new style threaded pin falls out and there is no trim feed back to the PCM YOU CAN TRIM IT TO THE MOON, ACTULLY TRIM/TILT THE PROP RIGHT OUT OF THE WATER AT 6000 RPM!

I now know what my Sterling needs to run properly with this 250 Pro XS 4s! Trim extenders or a set of positive trim wedges!

First and foremost- what you described is only ONE possible scenario. It's also possible that the trim may read HIGH, and prevent the engine from accelerating since the PCM would view that as an "over-trim" condition.

The best rule of thumb is to not attempt operating if or when you become aware that there is a problem in this area. Obviously- with you stuck on the water, you will do what you need to in order to get back to port.

Wedges and trim extenders are not approved for use with your engine. See engine installation instructions, and warranty/exclusions section of owner's manual for details.