The post is great and informative. As technology upgrades, fastener supplying companies should also check their fasteners qualities and should maintain it.
There are many fastener supply companies which provide fasteners in quantity but when one check their quality, it goes down. So, time to time, companies should also take responsibilties to provide quality in fasteners.
Hello Ann, I asked the very same question and sometimes they did not. There were times, granted not many, when emergency landings had to be made due to cowlings or flight surfaces coming loose and vibrating uncontrollably during flight. Of course, this can affect the airworthiness of the plane and consequently provide exceptional drag. It was always amazing to me how uninvolved some pilots were relative to pre-flight inspections. The "walk-arounds" recommended were sometimes cursory at best. My experience was during Viet Nam and there were so many aircraft coming and going at the Ogden Air Material Area (OAMA) it was impossible to say what part belonged to what aircraft. They were labeled with a date and placed in a special bin. Then you wait for a phone call.
This statement: "A secondary issue arises: finding safe and reliable methods of fastening assemblies that can protect against fastener loosening while minimizing assembly and maintenance costs. These methods must provide complete assurance of joint integrity under the severe conditions of shock, vibration, and thermal cycling common in aerospace environments" brought to mind Apollo 13 - if I recall correctly the explosion was caused by a defective part off the assembly line. I would be a lot more interested in maximizing safety then in minimizing the costs of the fasteners...
Robert--very interesting post. I think fastener technology has greatly improved over the last 20 or 25 years. During my "tour of duty" in the Air Force, we would sweep the runways three times per day for components that actually fell off the aircraft. It was amazing to me the parts we found. Our sweeper had the capability of lifting a part weighing up to 100 pounds--and we found them. Cowling, hundreds of screws and bolts, nuts, etc. you name it. Believe it or not, we never had an accident, to the best of my knowledge, as a result of components vibrating off but, I certainly don't know why not. The technology has definitely advanced since those days--thankfully.
The only issue that I have experienced with threaded inserts is the special tap needed for the OD of the insert. I have been in shops where they might only have one Helicoil tap for a certain ID thread. Production stops when the guy that keeps the tap in his tool box is on vacation.
I use steel inserts in two cases. One where a bolt will be removed repeatedly, or I have to fix a stripped out hole. I think the later is where most inserts are used. In many cases the insert has a stronger holding potential versus the original thread. I only wish I could get some of the more exotic sizes cheaper.
Load dump occurs when a discharged battery is disconnected while the alternator is generating current and other loads remain on the alternator circuit. If left alone, the electrical spikes and transients will be transmitted along the power line, leading to malfunctions in individual electronics/sensors or permanent damage to the vehicle’s electronic system. Bottom line: An uncontrolled load dump threatens the overall safety and reliability of the vehicle.
While many larger companies are still reluctant to rely on wireless networks to transmit important information in industrial settings, there is an increasing acceptance rate of the newer, more robust wireless options that are now available.
To those who have not stepped into additive manufacturing, get involved as soon as possible. This is for the benefit of your company. When the new innovations come out, you want to be ready to take advantage of them immediately, and that takes knowledge.
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