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  #21  
Old 04-19-2021, 03:00 PM
Richard Connell Richard Connell is offline
 
Join Date: Aug 2006
Location: Sydney Australia
Posts: 250
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Quote:
Originally Posted by Jslow2 View Post
where did you get the drawing that shows a screw to be used instead of an an3 bolt? Garmin g3x manual shows a an3-7a bolt is to be used there, torqued to 34-46 in lbs. A screw with an angled head just seems wrong in this application, and extremely unsafe.
Itís in the RV14 plans

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Maybe the factory can chime in with why. Iím sure thereís a reason.
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  #22  
Old 04-19-2021, 03:24 PM
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Walt Walt is offline
 
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I'm quite certain they spec'd the fastener to gain a little more clearance.
Personally I've always used the AN3 as called out in the Garmin documents with no issue.
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Last edited by Walt : 04-19-2021 at 05:32 PM.
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  #23  
Old 04-19-2021, 04:28 PM
Jslow2 Jslow2 is online now
 
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Location: Cement City
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I'm not an engineer, but it would seem to me a screw designed to be in a countersink should not be used in a flat washer, where only a small surface of the angle on the screw head is actually touching the washer.
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  #24  
Old 04-19-2021, 05:22 PM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 646
Default Deviation from plans...

Understanding that clearance between the bearing attach and the servo body was a concern, I used a AN525-10R16 instead of the AN509.
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Brian Decker
Retired Firmware Guy and Airplane Builder

2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.
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  #25  
Old 04-19-2021, 07:57 PM
N49ex N49ex is offline
 
Join Date: Apr 2015
Location: Wheaton, Illinois
Posts: 119
Default RV-14 Garmin GSA 28 Over Center

As a non-RV builder/ home built owner (but still find endless help, information, and enjoyment in this forum) who had more sketchy construction manuals to work with, this discussion points out an issue that I've seen here several times. That is, just because the Van's manuals and instructions are so good and comprehensive, you should not blindly follow them. Remember that at the end of the day you are the manufacturer, not Vans (not to malign the company, but face it, there are so many places already where builders deviate sensibly). So, a situation like the flat head screw and washer in these AP instructions should raise a flag. Go ahead and call Van's and ask what they were thinking, but clearly using a threaded screw here in sheer is a mistake. This is an application that calls for a close tolerance fastener, non-threaded in the area of load, such that repetitive and reversing loads do not hammer it to looseness. So, keep your eyes open, question when necessary, and do what makes aviation engineering and safety sense.
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  #26  
Old 04-20-2021, 07:36 AM
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bjdecker bjdecker is offline
 
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Quote:
Originally Posted by N49ex View Post
...but clearly using a threaded screw here in sheer is a mistake...
Neither the AN509 or AN525 are "threaded" for their entire length, and can be used in shear applications, just like AN3.
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Brian Decker
Retired Firmware Guy and Airplane Builder

2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.
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  #27  
Old 04-21-2021, 09:39 AM
ShortSnorter ShortSnorter is offline
 
Join Date: Dec 2013
Location: NOLA
Posts: 302
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To answer the question why the screw is used in lieu of a bolt: Clearance. An AN3 will not clear the servo when mounted per the plans.

Also, I did install the over center bracket as Tom showed in post #15.
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