After 20+ years on the line and, in many cases, spending almost as much time sitting in the desert, many of the light plates show both heat damage and damage to the paint due to dry conditions. On thing that is somewhat unique to the light plates used on the Lockheed L-1011 is that they are not engraved, but printed. In other words, all the legend was screen printed onto a white translucent layer of paint with the grey/blue cockpit panel paint used on the Lockheed L-1011.
The two main types of damage to the large paint areas can be seen below.
Most typically are edge damage to the plates around the instrument edges or instrument inserts. What happened there, is a basic chipping off of the paint due to mechanical stress such as dumps in transport, bumps during the de-installation and rough-handling while on the line. You will find, that most L-1011 cockpit panels required extensive plate touch-up work, especially around the instruments and edges, even while on the line and in day-to-day use.
The second type of damage that you can see above is a type of thermal (heat) stress that was caused by the plate back-lighting while on the line and to some extend to heating and cooling of the cockpit environment while it sat in the desert. Sometimes these cracks are called spider cracks because they resemble a spider net. In extreme cases, the cracks will originate from a darkened area in the paint that was caused by the bulb heat of the light behind the plate. The image below is a perfect example of that concentrated heat damage:
I will show the process of re-painting and re-lighting the original plates in a later posting. But for now, let's take a closer look at how the plates are actually lit. The electromechanical part that lights the acrylic plate, is screwed into the backside of the plate and comes off by simply removing a few screws.
The front-side of the plate shows the actual bulbs, a small plastic diffuser around them and the copper trace that creates the electrical connection for the bulbs.
The bulbs themselves are a very clever design and are meant for easy replacement on the line. Actually, to replace the bulbs the plate never had to be taken apart because the bulbs screw into the socket as seen below.
For the restoration effort, the idea is to replace the 5V incandescent bulbs with LED lights. I will show how to do that in a later posting.
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