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Hey that was quick thank you so much do you know what the 4-40 means as looking down the list im not quite sure which one i should be ordering as the ones i want have 1/2 inch of thread plus the head its not serious if they are a fraction longer, regards Rod
Hey that was quick thank you so much do you know what the 4-40 means
The following formula is used to calculate the major diameter of a numbered screw greater than or equal to 0: Major diameter = Screw # × 0.013" + 0.060". For example, a number 10 calculates as: #10 × 0.013" + 0.060" = 0.190" major diameter.
Why the US persists in its attraction to Imperial (which they often call 'English') units in what is mostly a metric world surprises me.Geoff
300 million + potential customers maybe one reason Geoff chaz@2b
What do they use in their aircraft? And can this cause problems when they are serviced at European airports?
All civil aircraft use Unified fasteners.
I'm almost certain Rolls-Royce use metric units and fasteners in their engines. I worked there for over 30 years but concerned with electronics/instrumentation etc so didn't have much to do with nuts and bolts. However I think the ones I picked up when walking down the yard were metric.
Well, a while ago a windscreen popped off an airliner and the pilot was half sucked out. That was traced back to a metric/imperial mixup in most of the screws holding it on IIRC.He survived...
Thats exactly what I am talking about. I remember that incident. And I'm flying this Thursday.... I shall be out with a RR guru tonight, I shall ask him what they use. Maybe I should check around the aircraft with my allan keys!
Ask him what he knows about the Hanger 9 Piper Pawnee too Bob..
Well, a while ago a windscreen popped off an airliner and the pilot was half sucked out. That was traced back to a metric/imperial mixup in most of the screws holding it on IIRC.
All the screws involved were unified threads - the main problem being that the correct screws should have been 10-32UNF but most of the screws fitted were 8-32UNC, (an easy mistake... 1/32 different diameter)
Not really. Aircraft fasteners aren't just bought from a local hardware shop; they have to have a certification for the product, the manufacturer and even the stockist. Whilst there are "aircraft standard parts catalogues" from which the designer will select things like fasteners the actual parts themselves are very tightly controlled due to the problems of counterfeit parts making their way into the supply chain.Part of the design process looks at opportunities to standardise parts for improved supportability and reduced through-life cost by reducing what is known as the "logistic footprint", but it's one element of a trade-off. A standardised fastener will usually be larger and heavier than is actually required, and its material may need particular fits or finishes on other parts to avoid corrosion, pick-up or fatigue. It might sound like a trivial amount of extra weight, but there are typically over 100,000 fasteners on a large commercial aeroplane and an extra gramme of weight on each is 100kg or freight lost on every flight (it's the freight that pays for the flights on most routes).For the military it's about reducing the spares and tools required to operate and support the aeroplane - the russians often use the novel approach of using non-standard head sizes on bolts and AF-sizes on nuts to minimise the numb er of tools needed for deployed operations. The T72 main battle tank could be completely dismantled using six sizes of spanner/socket, three screwdrivers and a couple of special tools!PDR
Which of your 'military' is supposed to say 'civil' ??
The illustration of the advantages would be comparing the soviet T80 tank with the american Abrams M1. The Abrams has a first-line tool kit (the one carried on the tank for maintenance done by the crew) that has over 250 items and takes up over half a cubic metre of volume. The first line tool kit of the T80 comprises five spanners, two screwdrivers, two hammers, a variation on a mole grip, a plier/crimp-tool thingy and a multimeter. The tool kit has a box that is about 24" by 15" by 3" thick. The only other items are the track-change tools, which are also much smaller and simpler on the T80 than they are on the M1.PDR
Sorry Civil = non metric and Military = metric