Adapter plate failed !!!

[M Towsley]

Re: Adapter plate failed !!!

Each part for the hub has this after it on the Classic Aero site: May or May Not have FAA approval Document.

Re: Adapter plate failed !!!

Luscombe foundation makes new pma hubs.

Are you sure they are PMA parts Mike?

I asked that to them a few years ago and came away thinking that they are not PMA.

Dave

[Ragwing nut]

Re: Adapter plate failed !!!

Luscombe foundation makes new pma hubs.

[ERicter]

Re: Adapter plate failed !!!

[QUOTE=astjp2;91576]I have 3, 2 at the shop and 1 in my spare parts pile at home...

Do you want to sell any of these, and what condition??

[astjp2]

Re: Adapter plate failed !!!

They are used, new ones are like uncut diamonds, they are out there but you wont find many along side of the road. I could get rid of one...Tim

[ERicter]

Re: Adapter plate failed !!!

Are you wanting to get rid of any of those?? And are they new or what condition??

[Hank Jarrett]

Re: Adapter plate failed !!!

Can I stop clutching at my chest now? ;-)

Hank

Re: Adapter plate failed !!!

Dave, it was sarcasm, sorry if I confused anyone, it was meant to be some humor that they were just grounding every airplane but didn't know why...tim

LOL

ok, I looked could not find, be aware that you can frighten old people like that!

[astjp2]

Re: Adapter plate failed !!!

Dave, it was sarcasm, sorry if I confused anyone, it was meant to be some humor that they were just grounding every airplane but didn't know why...tim

Tim,

Where did you find that AD? I cannot find it.

Dave

[PA1195]

Re: Adapter plate failed !!!

Ok and thanks. I suspected that's what it my be as their drawing shows a space forward of the spacer behind the prop's machined bore facing. So it's just to resist prop rotation on the adapter by reducing the clearance between the prop and hardware?

BTW that spec'd torque plus deg twist is currently still used by Harley Davidson (15-17'/# + 90Deg) and maybe others.

Edit: I've not seen the starter adapter in question, but I wonder if it has an inside chamfered radius similar to the prop in the Sensenich link to support the adapter at that location?

From these pics unlike the prop it would appear the adapter is mounted outboard of any flange radius: http://joea.com/phpBB2/viewtopic.php?t=2744 and https://www.facebook.com/SafestartSt...type=3&theater

Does the starter adapter come with bushings to fit around the bolts on tapered crank hubs? Maybe he makes two adapters...one to fit the tapered crank adapter with smaller holes, and one to fit over the larger dowels on flanged cranks. It could also involve using the smaller holes in the pics for the tapered, and the larger for flanged cranks...hard to know w/o STC in hand.

Gary

Re: Adapter plate failed !!!

The ones that Sensenich sold me with the prop do not fill the entire counterbore length so one is left with a counter bore that is
.050" (approx.) deep.

I sent them a sketch and asked to have the situation resolved. Of course the answer is the normal one the basic wordy but essentially this message "we know what we are doing, you won't understand it, its ok the way it is" .

Others often say they have no such problem so I am a bit perplexed or maybe I overthink things.

[PA1195]

Re: Adapter plate failed !!!

Dave can I assume the rear bushings to be installed in non-flanged/tapered crank installations (See P/N A-437: http://www.sensenich.com/files/docum...1261679535.pdf) were spec'd to replicate the machined extrusions on a flanged crank? Would they not prevent the face of a tapered crank from distorting when torque is applied, or do they not offer a firm flat face around the bolt to the adapter?

I also assume Eddie has a similar installation exclusive of the starter gear facing the adapter which 'should' have a tight fit around the attaching bolts to discourage warpage of the adapter.

Gary

Re: Adapter plate failed !!!

Interestingly I had lunch with a friend today and one of my sons. Both are mechanical engineers as am I, EE also so we were talking about analysis methods and programs.

I brought up this hub because I have two issues with it 1) an old one for me that the bolt torque will warp the hub flange when the prop has counter bored holes for a flanged crank with bushings installed, 2) this cracking event and my conjecture that the ring gear may induce cracking.

Both of the guys have access to the analysis software. My son owns a set but Lin the guy is finishing his PHd in ME and has access to much more software.

Anyhow I got an offer to model it with static and dynamic loads if I can supply dimensions. I said it would and will. That was before I read this thread tonight.

My beef with the bolt torque and counterbored holes is that I have 2 brand new hubs. One still in the bag and teh second that I installed using Sensenich instructions for torque. It Warped the flange and an older method of bolt tighten from Sensenich was to snug up the nuts by fingers and then turn X more revolutions based on bolt size and prop thickness. I think this method is better and reduces warpage. They no longer publish that method. It just annoys me.

Dave

[PA1195]

Re: Adapter plate failed !!!

How is that service offered anywhere with old airplane parts?

How was Eric's other part qualified?

I think the system of qualification remains the same in or out of Ebay doesn't it?

Don't know all I should as an owner/op/pilot, just have had the question raised a time or two by maintenance folks when I wanted to replace something worn with something that appeared to be in better shape.

But you raise a valid and interesting point...at what stage of use history should a mechanic conduct NDI or have it done on critical parts beyond a visual inspection...like this prop hub gizmo? Why does it take a hammer like an AD to initiate an in-depth inspection?

The other problem I keep swinging at is what caused the adapter too fail? Installing a new/certified one may only defer a similar event if other components or installation procedures are contributing to the stress. I'll leave it alone for Eddie and Fred to figure out. Not my plane, but Eddie is my friend and I drive by his Taylorcraft almost every day.

EDIT: No not advocating you not share potential sources...just that the part should meet design criteria. I guess to do that it would need to be inspected and approved by some testing method or facility.

Gary

Re: Adapter plate failed !!!

And yes Gary more investigation needs to be done however as you stated earlier Fred will handle that.

I have some conjecture and theories but the man on the scene is the one that can act.

I don't think that you would advocate that I not share potential sources, would you?

Dave