Don't let their simplicity fool you
By Joe Escobar
Aircraft windows — such simple looking aircraft components. Because of their apparent simplicity, their importance and criticality can sometimes be taken for granted. But if you end up having to replace a windshield due to negligence or damage, you will probably never take them for granted again. With some aircraft model windshields easily costing 25,000 dollars, it can be a very painful lesson to learn.
Oh, the pressure!
In terms of area, some windshields are the largest components on the aircraft pressure vessel that do not have any other structure supporting them like ribs or stringers. The cabin pressures that they must endure make even small defects critical. Any flaw can quickly lead to disaster if not attended to.
Tough operating conditions
Windshields and windows endure some harsh operating conditions. They are subject to temperature extremes that can occur within minutes. At high altitudes, they are subject to higher amounts of damaging UV radiation. Some scientists even state that minute particles of volcanic ash from major eruptions such as Mt. St. Helens linger in the upper atmosphere and are causing accelerated crazing of aircraft windows.
They are even subject to damage on our part during routine maintenance. Using paper towels, shop rags, or unapproved cleaning products can also cause unwanted damage when cleaning the windows.
Now that we are aware of the cost of replacement windows, and the severity of defects, how can we prevent damage to windows? Well, one of the first steps is through employee awareness. If new employees are not aware of proper window maintenance techniques, then they are more likely to cause damage. Even non-maintenance personnel like the aircraft cleaning crew need to be made aware of proper window cleaning techniques.
"There are plenty of products that you can use that are not very favorable to windows," says Greg Piland of Wichita, Kansas-based Lee Aerospace, a repair station that specializes in aircraft window inspection and repair. Piland claims that much of the damage that windows sustain is from routine cleaning.
"People need to be aware of just how scratch sensitive windows are. Bug parts and dirt can cause an enormous amount of damage if they are rubbed all over the window while cleaning it,"adds Piland. Also, a fresh water rinse is very beneficial prior to wiping windows.
When cleaning the windows, use only approved products. In many cases, that is just a mild soap and water solution. Some commercial window cleaning products that work great on your bay window at home can cause an extreme amount of damage to acrylic aircraft windows. Always refer to the manufacturer’s maintenance manual.
As far as the cleaning material, you need a very soft cloth. Piland says that there are quite a few products available commercially that work extremely well. You want it to be soft, absorbent, and non-abrasive. Sheila Wadden agrees. She is a technician with Micro-Surface Finishing Products, Inc., a Wilton, Iowa company that manufactures Micro-Mesh products and also offers aircraft window repair services.
"Something that I try to tell all of the technicians I talk to is not to use paper towels," explains Wadden. "It is a wood pulp product, and is going to give you light hazy scratches if you use it."
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