Adapter plate failed !!!

[ERicter]

Had a failure on adapter plate for taper crank, felt a different vibration, not much.... Went back and landed,and found the prop very loose, very fortunate. Reading alittle on these it seems like they have had issues.

Am looking for a new one?? Anyone have any leads.

[N96337]

Re: Adapter plate failed !!!

Yikes!! I've heard stories about them failing but never seen one. I've had people tell me that it's from hydrogen embrittlement due to cad plating....I don't know, but it would make sense in some cases.
Glad you got back with no problems!
John

[astjp2]

Re: Adapter plate failed !!!

All of the ones that I have seen cracked did it along the keyway. That was a major structural failure!

[Guest]

Re: Adapter plate failed !!!

What kind of prop was on it?

The bolts look big, are they 3/8" bolts?

Dave

[Guest]

Re: Adapter plate failed !!!

Here are two.

http://www.ebay.com/itm/Continental-C-85-Propeller-Hub-Complete-p-n-3745-with-flange-pin-p-n-3991-/111964239518?hash=item1a1196b69e:g:k-4AAOSwAvJXB~WW&vxp=mtr

TAPERED SHAFT HUB • $295 • FOR SALE • Continental Tapered Shaft Prop Hub. Known History. Good Condition. Fits A-65, A-75, C-75, C-85, • Contact James D. Herpst, Friend of Owner - located West Columbia, SC USA • Telephone: 803-309-3130 . • Posted April 21, 2016 • Show all Ads posted by this Advertiser • Recommend This Ad to a Friend • Email Advertiser • Save to Watchlist • Report This Ad

[PA1195]

Re: Adapter plate failed !!!

There's also a starter adapter ring gear attached to that assembly.

Good luck Eddie. Did Fred locate one yet?

Gary

[ERicter]

Re: Adapter plate failed !!!

It's a McCauley 7142 put on when I bought the plane in August of 14. It is broken all the way around, at high rpm no vibration because it was pulling forward and locking in.

Gary brought up a good point about the ring gear. If that has anything to do with it. I'm happy to be in one piece and have the craft also.

Haven't talked to Fred yet Gary.

[ERicter]

Re: Adapter plate failed !!!

I could check on bolt size, I believe they are 3/8"

[PA1195]

Re: Adapter plate failed !!!

I wonder: Is the fatigue cracking a result of a radial or forward/thrust imbalance? Radial to me would be one blade or part of the hub assembly is heavier...thrust would be one blade has more pitch. Then there's tip tracking which I know little about the effects of, but it's often discussed as being important (+-1/8" for example). Time in service for the affected parts? Any prior prop strikes?

Eddie has to be made whole again via repairs as float season will soon be here in Fairbanks Alaska and we need a dedicated fisher for the big ones.

Gary

[Guest]

Re: Adapter plate failed !!!

It's a McCauley 7142 put on when I bought the plane in August of 14. It is broken all the way around, at high rpm no vibration because it was pulling forward and locking in.

Gary brought up a good point about the ring gear. If that has anything to do with it. I'm happy to be in one piece and have the craft also.

Haven't talked to Fred yet Gary.

I noticed the starter gear and wondered about that.

Is that an STC? I never saw an A65 like that.

So you have a ring gear. Do you also have an extender that moves the prop forward?

Dave

p.s. There are a lot of those hubs out there for a long time and the common failure is as Tim mentioned, longitudinal cracking at the key way. Makes me very curious about that starter setup, what loads it imparts when cranking, extenders that move the prop forward... Moving the prop forward with ring gear and/or extender will increase the bending moment at the rear plate where it cracked- raises curiosity

[Bigdog]

Re: Adapter plate failed !!!

The original design probably only considered wood props which have natural dampening. Maybe a metal prop and a starter ring is a bridge too far.

[PA1195]

Re: Adapter plate failed !!!

http://vb.taylorcraft.org/showthread.php?6160-Safestart-Starter-System&highlight=hamp+starter

https://www.facebook.com/SafestartStarterSystems/

http://joea.com/phpBB2/viewtopic.php?t=2744

I'm not suggesting it contributed to Eddie's event, but the assembly probably should be examined periodically.

Gary

[Guest]

Re: Adapter plate failed !!!

Thanks for the links and pictures Gary.

I am suspicious that this failure is related to the STC.

The i.d. of the ring gear appears to have left a mark on the hub and it intersects the inside edge of the hub lightening holes.

Looks to me like the crack may have started there also, each lightening holes appears to have crack at the point I mentioned..

Eddie did it have prop bushings installed on each bolt?

Eddie, if I were you I would consider contacting the FSDO, I am thinking that this is not a one only event.

Dave

[3Dreaming]

Re: Adapter plate failed !!!

For me there are to many things that we don't know about the history of the flange to start getting suspicious of the starter STC.

A crack like this is another good reason to be removing the propeller to remove the nose bowl for annual inspection. By having the propeller and hub removed you can inspect the rear of the hub along with the keyway for cracks. This would be an area that is almost impossible to inspect without removing the propeller and the nose bowl in place. Those with a flanged shaft engine can take a good look at the flange too.

[Guest]

Re: Adapter plate failed !!!

Tom,

It sure makes your prior point about removing the prop and nose bowl for inspection.

Dave

p.s. Suspicion is relative low cost I don't mind spending it Suspicion does mean I condemn it or that it is the cause only that it seems a possible and perhaps likely cause. FSDO could dig in and really figure it out. Eddie was lucky this could really hurt someone. Wouldn't want to see anyone get hurt.