ggower_99(at)yahoo.com
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 Posted: Tue Mar 07, 2006 7:09 pm Post subject: Grades of Nuts & Bolts. |
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Hope I get the idea right, But what realy holds the propeller in place is the even and correct pressure of the propeller to the hub, not the bolts directly. if torqued correctly they will not fail. If they are loose the vibration from the engine (moving the propeller over the hub) will cut them, sooner or later, as a cold shisel (sp?) will not matter if they are 1" diameter AN bolts. or 1/4" diameter Grade 8.
Some countries, and here some 20 years ago, where importing was a real problem:
Time, money and paperwork and most time the parts were lost in Customs, but the bush pilots kept flying, Common sence and bench destroy testing, gave good and no good options to all of us.
Yes, now with NAFTA we can get easy all AN parts we need realy soon , just pay shipping (courrier) and some "mild" paperwork most of the times...
Saludos
Gary Gower.
"n801bh(at)netzero.com" <n801bh(at)netzero.com> wrote:
There is another under laying cause for the "breaking" of the grade 8
bolts.
It's not the fact that they are grade 8 alone. Probably not the right size,
not torqued properly, over torqued, no locking nuts, pins, etc, or a
combination of the aforementioned. Somebody forgot to do something. Six
properly install 3/8" grade 8 bolts would not be the problem.
Larry, N1345L, www.skyhawg.com
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This problem all came up several years ago for one big reason. There were some bogus companies fromaround the globe manufacturing poor quality bolts and marking them as grade8 to increase their profit margin. This first surfaced in the racing comunity because of the nature of the business. We strived to hold the car/boat or whatever racing craft together with the best stuff for safety and durability. We assumed the wholesaler was honest and we quickly found out that was not the case. This started the whole debate on grade8 being inferior. Aircraft stuff had a far better way to deal with quality control, that was to hold the manufacturer, wholesaler to a paper trail of traceability. Even that didn't stop all the fraud to happen but it was a lot less in that market. Some companies were charged and found guilty. There was even one that was based in the far east where the owner did fall on the sword. It turned out all the people who bought for the major manufacturers like Dorm!
an, ARP,Fastenal, and others didn't experience the same level of poor quality stuff. As cy pointed out the incident in question was found to have one AN bolt that didn't fail and five other ones that were marked as grade8 but turned out to be of far less quality. Funny how that part of the story never lives on like the rest of it does.
do not archive
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