Inspected Screws
Inspected Screws
(OP)
This question has been asked here before, almost certainly by me at point in time. I am asking it somewhat differently this time.
Is there a grade or class of metric fastener that comes with batch numbers and/or inspection reports and/or some other form of traceablilty, suitable for mounting in an aircraft? Another option would be UNC screws of some size. Most aircraft screws are UNF or UNJF.
My actual problem is that I am trying to find anti-vibration mounts that will be delivered in six weeks or less. Someone is searching a warehouse, and I am probably going to have to use whatever screw thread is available.
Is there a grade or class of metric fastener that comes with batch numbers and/or inspection reports and/or some other form of traceablilty, suitable for mounting in an aircraft? Another option would be UNC screws of some size. Most aircraft screws are UNF or UNJF.
My actual problem is that I am trying to find anti-vibration mounts that will be delivered in six weeks or less. Someone is searching a warehouse, and I am probably going to have to use whatever screw thread is available.
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JHG





RE: Inspected Screws
RE: Inspected Screws
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http://www.reidproducts.com/index.php?page=na
STF
RE: Inspected Screws
As israelkk noted there are also a few commercial aerospace metric thread bolts/screws listed on the SPS website.
RE: Inspected Screws
I can see stuff in the SPS catalogue that should work. It turns out that my anti-vibration mounts are available from stock with 1/4-20UNC threads. My other option is to drill and tap out the mounts so that I can use an AN bolt.
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JHG
RE: Inspected Screws
The other option, as you noted, would be to create an "altered item" part number from an existing fastener that has the proper level of traceability and quality control for the application. This is commonly done in the aircraft industry. But you would need to create engineering documentation that defines requirements for procuring the existing part, modifying the part, QA of the modified part, and controlling usage of the modified part.
RE: Inspected Screws
The altered item is starting to look attractive. SPS has a traceable, high strength stainless steel cap screw which would suit my purposes if I were the only one doing the ordering. I have a limited ability to prevent someone from using a regular 18-8 stainless steel screw.
The altered item would be the anti-vibration mount. The supplier warned me that modification would void any warranties, but I did not know these things had warranties. If I use 3/8-24UNF, the easiest bolt to find would be the AN6 bolt I would prefer they used.
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JHG
RE: Inspected Screws
bolting down, the vibration mount is of no concern an can be modified without the manufactures approval.
If the vibration mount has metrical screw threads I would guess that this is a commercial vibration mount without any failsafe feature.
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I am using a cup type mount from Shock Tech. Various tapped holes are available if I am willing to wait for them.
I would not call these fail safe. They are all metal, which the aircraft people prefer over rubber.
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JHG
RE: Inspected Screws
One purpose of an altered item drawing is to control the source of the part being modified, which in this case is the fastener. All you need to do is add a table listing the approved source(s) of supply for the part and the supplier part number. You can also add a drawing note describing any traceability requirements at procurement, manufacturing, inventory, and throughout its service life.
RE: Inspected Screws
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JHG
RE: Inspected Screws
RE: Inspected Screws
I figure that, but we cannot manage 19-20 week deliveries, much less 18 months. The price was extremely reasonable. If they hand stocked that stuff and charged $200, I might have gone for it. The stuff we build does not go on the shelves at Walmart.
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JHG
RE: Inspected Screws
You will need to produce your own engineering documentation for the fastener, and you will need to collect and maintain all of the documentation required for traceability of these fasteners. But you should be able to get the exact custom fasteners you require within just a couple weeks. And at a cost that should be reasonable.