How many threads???
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How many threads???
Had an arguement at work today with a "so called" LAE, me being a mere A&C fitter, couldn't really argue too much! . .. .Can anyone tell me for certain how many threads have to be showing through a standard stiff-nut to be in safety??. .. .Thanks guys!. .. ."Some days you are the pigeon, some days you are the statue!"
If you are working on US manufactured equipment, this reference from AC 43.13-1B is applicable, unless there is a particular installation requirement in the maintenance manual or in standard practices.. .. .Chapter 7. Section 3. Para 3-36.. . </font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica"> All bolt installations which involve self-locking or plain nuts should have at least one thread of the bolt protruding through the nut.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica"><a href="http://av-info.faa.gov/dst/43-13/Ch_07-03.doc" target="_blank">FAA Advisory Circular AC 43-13-1B</a>. . . . <small>[ 13 March 2002, 02:04: Message edited by: Cyclic Hotline ]</small>
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Me (Haha!). .. .He said minimum of three, I said minimum of 1.5!!. .. .Fitters 1 .v. LAE's 0. .. ."Some days you are the pigeon, some days you are the statue!"
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This LAE wasn't signing the CRS, he was causing problems for another LAE, by saying that the nut was not in safety.. .. .All sorted now!. .. .Cheers guys. .. ."Some days you are the pigeon, some days you are the statue!"
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Golden Rivet - . ."If the LAE wants three threads, he should have three threads - at the end of the day its the LAE who is signing the CRS.". .. .I know what you mean, but don't go too far down that road..... .The LAE is 'only' signing that the job has been done iaw published procedures. The licence doesn't give you the right to demand your own preferences. If he disagrees with what's been published then there is a better time and place to argue than during the job.. .. .Too many LAEs in my life have thought themselves better qualified than the design organisation and it always means trouble - he should read notice 3 if he thinks he can do everything.... .. .(anyway, 1 1/2 threads have always been good enough for me, but split pins are better!) <img border="0" title="" alt="[Wink]" src="wink.gif" />
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Coriolis. . . . </font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">but split pins are better! </font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">Oh-no not another Brit engineer that loves to cover the damn aircraft in split pins and wire-locking <img border="0" title="" alt="[Frown]" src="frown.gif" />
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If the LAE wants 3 threads he should have 3 threads. Maybe in this situation its fussing over small things.. .. .As an LAE if I am not happy with something the plane don't go. Just because a bit of paper says something it don't mean it's right. I will discuss matters take advice consult all relevent manuals but if I am still not happy thats it.. .. .We may not have authority to deviate from manuals but we are the people signing the bit of paper and if things go wrong they will wave that signiture in your face and hold you accountable. Our ability to know when somethings not right is quite important, isn't it better to be cautious and go for 3 threads rather than 1.5. Think of the implications if things went the other way round.
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I thought the torque thats retaining the nut is acting on the threaded portion of the bolt in the nut. The bit sticking out is irrelevant. The reason for 1 1/2 or 3 threads is to ensure that there is some reasonable standard for providing an adequate torque surface. As for nailing you for your signature in the event of accident/incident; if the work was accomplished per a manual, and you can show that manual reference then you did as instructed by the OEM or your Engineering department. If the fastening is significant enough that they dont want the nut falling off, they'll use one of Coriolis' split pins.
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Re-engineering or artistic licence?. .. .I think the question that is emerging here is does the LAE have the right to exceed the quality requirements if he feel the situation demands as such.. .. .The Captain can refuse to take an aeroplane into the sky - why not the engineer.. .. .The aircraft manufacturer/designers/Tech service Engineers are not always right. You've only got to look at the amount of AD's,SB's,SL's, manual ammendments ( need I go on )to see this !. .. .I think I agree with Reboot on this issue - If I'm not happy with something, it does'nt matter how many bit of paper my manager puts in front of me - It dont go.. .. .You only get one chance in this industry.. . . . <small>[ 24 March 2002, 10:08: Message edited by: Golden Rivet ]</small>
Sorry about the above entered in error!!!!!!. .. .A captain can refuse to take an unserviceable aircraft.. .. .If he declines to take a serviceable aircraft which is within the MEL but has restrictions with which he is unhappy he is going to face the chief pilot particularly if 150 pax are left in the terminal. . .. .If he refuses to take a an aircraft which has been declared serviceable by engineering and is so ( a worn within limits tyre might be an example) he will find his career path leads over the nearest cliff.
Freighterman I think has hit the real point, which is thread friction or running torque. No point in having 3 or 33 threads showing if there is no friction between the mating surfaces of the threads. How often do you see stiff nuts reused without there efficiency being tested?. .. .If you are inspecting a joint how often do you take a spanner back off the nut and see if it has any friction? How often do you see screws hanging out of wings because anchor nuts are never replaced? How many times have you found three threads showing with the nut threadbound and the bolt loose? . .. .Surely all that the thread protrusion actually says is this bolt is through the nut and as such is a visual indicator of that fact.
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I thought that might jog some elbows!. .. .I'm 100% with Rob L and Freighterman, and not entirely out of step with GR.. .I didn't mean to imply that if the LAE isn't happy he shouldn't say so, 'cos we're the final proper check anything gets before she goes airborne..... .. .However, I maintain that the right and duty to say so does NOT include making up your own rules about what's OK - I've known too many who have said (eg). ."This bearing lose in it's housing and I know of. .another bearing somewhere else which has been bonded back (instead of roll staked) under repair scheme xyz. Therefore I will bond THIS one in place because I'm an LAE. I don't need to consult Tech Services/design/manuf because I have enough experience to decide for myself". .. .I submit this is not where the LAE should be going, is all. (But I guess some don't agree?) <img border="0" title="" alt="[Smile]" src="smile.gif" />
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Being an LAE dosn't give you the right to do something wrong against the manuals I do agree.. .. .What I am saying is sometimes you know something is wrong when the book says its right then I belive you shoud say no. Shouldn't our experience be used as an additional safeguard.. .. .Captains not taking A/C I know they can get a lot of stick if they refuse one thats OK by the book but they can still do it.. .. .This could lead on to is a five minute delay and working IFE with happy passengers better than on time with no IFE and angry passengers. Been there myself and had to take the stick for delaying the A/C rather than being thanked for getting the IFE working, the passengers thanked me though.