Boeing’s Recipe for a Southwest’s Sandwich
Addendum to Southwest Air:
Pursuant to the post title; What’s in a name like “Southwest Airâ€?
An electronic capacitor is formed much like a sandwich …by taking one layer of meat and covering both of its sides with two layers of a common substance such as bread.
In an aircraft, when two layers of aluminum (which are analogous to two slices of bread) are separated by a layer of undesirable moisture …something has to give when the moisture becomes a solid.
After all, when condensation becomes ice, its covalent bonding causes its mass to expand.
The resultant increased volume acts like a lever in between this unlikely composite of aluminum layers.
And as a result, a work occurs which affects the primary fasteners which are designed to hold these aluminum sandwiches together.
When this work takes place over and over …in constantly reoccurring short cycle periods …the rivets are made to expand and cause enlargement of the whole whose precise diameters in the skins of the aluminum parts …and skins they which were meant to remain fastened to …in order to adhere one to one another.
As a result the integrity of the physical bonds’ properties is subject to a working process which causes a continued weakening of the integrity of the bonding components.
Rivets were not designed to work …or move.
Working rivets, for one, lose their high tolerance and their rivet holes can become subject to slop.
When enough slop occurs, the differential cabin pressure in flight will force warm moist air past the rivet’s slop spaces …which will freeze and in turn …further exasperate the slop’s enlarging processes until a point in time at which these originally high tolerant rivet holes …will suffer enough stress …forming stress cracks …especially when the airframe undergoes sudden stresses …turbulence being just one such real example of many such normal stresses an airframe will encounter and withstand …landing, take offs and cabin pressurization cycles not withstanding.
As such, the interior surfaces of aircraft must be treated with special attention with respect to employing specialized coatings and sealants.
Even the unique type of rivet specifically chosen and employed for a specific purpose becomes a critical consideration crucial to the success of any one of a number of specialized design applications.
The science of bonding has so evolved to an art form so as to become a detail oriented science in order to address each of any number of a myriad of special purpose applications.
Strength and hardness are just two such considerations which have been concerns for many years.
The other considerations unmentioned are enough to boggle the mind.
Now, add to the mix of what considerations which may conspire to attack the integrity of a rivet’s intended useful purpose …a consideration of electrical current …electron flow due to a differential potential which exists between the outer and inner skin of an aircraft …and you have the opportunity to take bonding science into another dimension which has its own set of stages and levels …each with their own unique set of details whose considerations involve more understanding far above my pay grade.
Just thought this would make a good follow up to my last post.
So, next time you fly; be sure to buckle your seat belt and, as always …
Enjoy your flight.
I’ll have a Jack and Coke; better make mine a double please.
All the best,
Bill
