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  #1  
Old 01-09-2016, 05:22 AM
Galenkillam Galenkillam is offline
 
Join Date: Oct 2014
Location: Appleton, WI
Posts: 34
Default Flight control attachment bolts/nuts?

I will be a newbie to IAC competitions this summer and understand I need drilled bolts with castle nuts on the control surfaces. Can anyone confirm that AND are there any comments about replacing mine on my 8?
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Old 01-09-2016, 09:12 AM
Ron B. Ron B. is offline
 
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Location: Yarmouth, Nova Scotia
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It's my understanding that if the bolt goes thru something like a rod end bearing, and that the nut can be torques, i.e. the rod end tightens on the mounting ears that a lock nut can be used. If the bolt can actually rotate freely because the install has no bearing surface then the nut cannot be torqued then a castle nut and cotter pin is required. Van's aircraft have some of both installations.
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  #3  
Old 01-09-2016, 10:57 AM
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climberrn climberrn is offline
 
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Default Follow the plans

Was told by the FAA during my inspection that the "standard" used to be castle nuts on control surfaces and linkage, but vans calls out for nylocks in many places. It is best to stick with what the manufacturer calls out.

Of course, if you are the builder, than you can do whatever you want. Would not suggest it though.
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  #4  
Old 01-09-2016, 12:57 PM
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Lucio I-NLCM Lucio I-NLCM is offline
 
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Location: Milano Italy
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Default + casle

Hi
all my control bars are locked with this: http://www.aircraftspruce.com/catalo...es/ms17825.php

I don't want never think about it

here the pitch control idler arm

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  #5  
Old 01-10-2016, 06:31 AM
sblack sblack is offline
 
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This is a bit like primer wars. I know an A&P who won't sign an annual unless all lock nuts are replaced by castelated nuts on drilled bolts with cotter pins. Then again I've seen cotter pins fail.

I thought 43.13 said that if the bolt doesn't rotate a lock nut is appropriate. It's probably a question that is difficult to get agreement on.
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  #6  
Old 01-10-2016, 08:04 AM
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lucaperazzolli lucaperazzolli is offline
 
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Location: Trento, northern Italy
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Quote:
Originally Posted by sblack View Post
This is a bit like primer wars. I know an A&P who won't sign an annual unless all lock nuts are replaced by castelated nuts on drilled bolts with cotter pins. Then again I've seen cotter pins fail.

I thought 43.13 said that if the bolt doesn't rotate a lock nut is appropriate. It's probably a question that is difficult to get agreement on.
I choosed MS17825 self-lock castle nut for pitch control line, three small plexy windows (one in the baggage area and two for the elevator horns bolt) complete my pre-flight check.

Pay attention in the central control column where pins may be worse than nothing. Pal nuts (MS27151) are another option (maybe).

MS17825 self-lock castle nut:





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  #7  
Old 01-10-2016, 08:25 AM
RVDan RVDan is offline
 
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There has often been controversy over the requirement for the use of castellated nuts on flight controls and for small airplanes, certified under part 23. 23.607 addresses this. The origin of the rule is all the way back to the CAR's from the 30's. But even better, AC23.607-1 provides more details. Specifically it requires castellated nuts to be used where movement of the joint may result in motion of the nut and or bolt. So the idea is that if there is a solid stack up of the bolt through a bearing, bushing or brackets where the bolt is tightened and no rotation of the bolt (or on the bolt) is intended as a part of the joint design, a castellated nut is not required. In this type of joint rotation occurs on a inner bushing or a spherical bearing, or other bearing and the bolt is through the inner race in a solid stack up. In contrast if the joint is designed to rotate on the bolt so that the bolt itself is actually a moving part of the joint, (rotation of parts relative to the bolt) then a castellated nut is required. The principle concern is that the rotation of the bolt or nut will put enough torque on the nut to loosen a self locking nut.

In helicopters, there is a requirement for double safeties (27.607) that says that if a joint is critical to safety, it must have 2 locking devices. That requirement is driven by vibration (helicopters shake a lot), where it has been found that certain vibratory frequencies will loosen a stop nut and others will break cotter pins, but the 2 frequencies are normally significantly different. So what you find in most helicopters flight controls is the castellated nut with an elastic self locking feature. This often gets confused with the airplane requirement.

In any case, the use of a castellated nut in our airplanes is always OK, but not always required. The use of double locking devices is never required, unless there is some specific environmental issue that would drive that and incorporated into the design. It won't hurt anything to use a double locking nut though.
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  #8  
Old 01-11-2016, 11:14 AM
rdrcrmatt rdrcrmatt is offline
 
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Newbie question. I come from motorcycle road racing background. We safety wire everything. I would drill through the side of a nut on a corner to run safety wire.


Why isn't more safety wire used?
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  #9  
Old 01-11-2016, 12:37 PM
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Raymo Raymo is offline
 
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What RVDan said. I opted to install castellated nuts and cotter pins in all moving control areas.

From 43.13:

7-64. SELF-LOCKING NUTS. These nuts
are acceptable for use on certificated aircraft subject to the aircraft manufacturer?s recommended practice sheets or specifications. Two types of self-locking nuts are currently in use, the all-metal type, and the fiber or nylon type.

a. DO NOT use self-locking nuts on parts subject to rotation.

b. Self-locking castellated nuts with cotter pins or lockwire may be used in any system.
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  #10  
Old 01-11-2016, 08:51 PM
sblack sblack is offline
 
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Quote:
Originally Posted by rdrcrmatt View Post
Newbie question. I come from motorcycle road racing background. We safety wire everything. I would drill through the side of a nut on a corner to run safety wire.

J
Why isn't more safety wire used?
On most of the bolts holding the surfaces on the access is limited. Putting the nuts and washers is difficult. I can't imagine trying to get my fingers in there to safety wire all those nuts.
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