Adapter plate failed !!!

[PA1195]

Re: Adapter plate failed !!!

Yes I agree it needs to be examined, and the how of best to do that is out of my frame of reference and training. I suggested to Eddie he have the prop looked at for conformity (maybe as you noted via TCDS compliance plus balance and pitch). The other components...hub assembly, starter gear, and crank runout would be good to look at.

Having it done with his mechanic's agreement is important.

I guess a question needs to be asked: Where would someone find similar reports of failure? I looked on the FAA's "broken or defective stuff reports" but couldn't bring up anything regarding the failed A-3745 part.

And yes going forward safety is #1 even if it takes some form of suggested or mandatory inspection procedure or interval. If it doesn't depart the plane a broken part and excessive vibration can create a hazard in flight and a distraction to the plane's occupants. Think "auto rough" over bad terrain or water.

EDIT: I believe Eddie has a McCauley 1A90 round tip @ 71/42. It's Item 7 in TCDS A-696 I think so's that ok for a C-85 with tapered crank?

Gary

Re: Adapter plate failed !!!

All good points Gary but I would not want to have someone hurt or killed due not having this looked into.

It is a very odd failure.

Dave

[PA1195]

Re: Adapter plate failed !!!

It's Eddie's choice of course, but involving the FSDO comes with a degree of risk. I'd not do it if it were me without first consulting my with maintenance folks and agreeing on a plan of action.

Bringing in inspectors who may have no idea what the part is can create confusion, strife, and a great paper inquisition. Was a MDR filed; were there preceding activities that may have led to the failure of the part; and how's everybody's logs and documentation BTW? I needn't go on.

I went through this with my former PA-11 and their unrequested presence due to major issues from a lack of prior maintenance. While eventually ending well due to plenty of $ and a conformity inspection it made the well qualified mechanic's job more stressful than it needed to be.

It also assumes they're capable of diagnosing the source(s) of the problem, and unless they are, then what will they bring to the party?

Gary

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.

7142?

What model? 1A90? 1B90?

7142 is too short according to TCDS.

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.

[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.

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

[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

[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.

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

[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

[ERicter]

Re: Adapter plate failed !!!

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

[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.

[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

Re: Adapter plate failed !!!

Here are two.

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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