Is anyone a Structural DER?

[Guest Anonymous]

I need to find or hire a Structural DER to do a ridiculously simple task.

To wit, I cannot convice a even one local MIDO guy to permit me to use a single first oversize bolt to mount a control wheel to the control shaft in a repair action.  I cannot convince them that the tensile forces in the control shaft will not change -- and that the compressive loads at the joint itself will be LOWER, and not higher.

I am an engineer, and I have all the math and can send it to you -- see the attached COSMOS graphics.  All I want to do is replace the Mooney 3/16 taper pin with a first oversize 3/16 bolt (NAS 6603-14X).  The shaft is alloy steel with a constant section, and the hole is well over the diameter of the bolt from the control wheel end.  The bolt hole is distorted (elongated) only in roll, and by only a few thousands.  It is not cracked or crazed.  It probably distorted becasue of a poor line reaming job when it was reamed for the taper pin.  I want to save it, becasue a replacement shaft is over $500.

All they can say is, "get a DER".

Slight change in the FAA moto -- They are from the FAA, and they are here to be helpless.

RFB

[Kwixdraw]

You need to get the motto correct. "We're from the FAA and we're not happy until you're not." 

[piperpainter]

I can't help but I know Jim and Me were talking about this. I hope they let you do what you need to.

[Gone]

Robert:

Hi.  I just sent you the DER directory and it has 14 names in WA alone, starting on page 127.  Hope that helps.

Good luck and let us know how it all turns out.

 

[Piloto]

A MIDO inspector has no authority to approve a design change or repair. MIDO inspectors are parts manufacturers (PMA) inspectors and they go by previously approved data. To get a field approval you need to check with your local FSDO office. What you describe is a standard repair option that does not justify a field approval process. The use of oversize fasteners for repair is common practice in aviation. Just have it look by your IA. Don't bother your FSDO for this.

José

    

[KSMooniac]

I'm an aircraft engineer and agree with José about this situation.  The MIDO folks aren't the right ones in any case.  If you would still like to consult with a DER, PM me and I'll see if my friend is interested.

[Guest Anonymous]

Quote: KSMooniac

I'm an aircraft engineer and agree with José about this situation.  The MIDO folks aren't the right ones in any case.  If you would still like to consult with a DER, PM me and I'll see if my friend is interested.

[KSMooniac]

I'm afraid that might be the modern FAA...they're trying to avoid any liability I guess.  Too bad there is no accountability with that bunch for not doing their job.  If they don't do field approvals, then why are they even needed???

[Guest Anonymous]

Quote: scottaviation

Re: Yoke attachment bolts for later 201 style yokes

Posted Feb 25, 2010 11:12 PM

Scott, I've got a 77 201 and just removed my yokes for powder coating.  They do infact have the bolt going through the side, washers and nylock nut, I remember this quite clearly because they also had a set screw hidden in the back that needed to come out aswell, found that out the hard way when they wouldn't come off easily.  It's a good heads up for anyone removing their 201 style yokes for repaint etc. I took a couple of screenshots from my 201 parts manual, hopefully it will help explain things better.  From the parts manual item 10, the bolt used is an AN4-24A.

Good luck,

Chris

« Last edit: Feb 25, 2010 11:15 PM by scottaviation»

77 M20J Project

[Piloto]

Quote: KSMooniac

I'm afraid that might be the modern FAA...they're trying to avoid any liability I guess.  Too bad there is no accountability with that bunch for not doing their job.  If they don't do field approvals, then why are they even needed???