This robot girl - gynoid - is used as a demonstration model by the film "AI: Artificial Intelligence", to show several aspects of their take on robot behaviour and construction. In this still, the gynoid's face is sliding apart for maintenance, after the human instructor commanded her to open her mouth, then reached in and pressed a release mechanism on the roof of the mouth.
When he did this, her face muscles stopped moving, and assumed a default position. Shortly after this, her face moved forwards from her head and parted into two segments: the upper half containing her eyes and nose rotating upwards, whilst the lower half rotates downwards. But, how realistic is this?
The face is by far the most expressive part of the body. The densely packed musculature conveys our moods, and shapes our words. So, it is a part which regularly comes under intense scrutiny, whilst meaning is being ascertained. As such, having a join between detachable parts in the middle of it, seems poorly thought out design. Unless the upper skin is some form of shape memory material, it would be extremely hard for the 'surface musculature' to continually flow over the join in a wide variety of expressions, without something showing.
There were two other films that showed the face being the access point. The much-older Westworld and Futureworld both showed the face being removed to perform maintenance on the optics and the head. However, in both cases, the face was removed as a single unit; there was no joining strip across it. This does seem the far more sensible approach to take, as facial expressions would thus be unaffected by the hatch edges themselves, and could likely continue, even without the face being attached to anything greater.
Perhaps Total Recall: 2070 had the most realistic take of all. In their system, the access panel was in the top of the head. It was accessed in the same manner as a brain surgeon accesses a human brain. Once exposed to the air, components slide out for easy access. This does seem to make a great deal more sense. However, there are other reasons you might like to take a face panel off of an android or gynoid. The most obvious of which being, to put a different face onto it.
Such an ability would once again, throw open the whole concept of embodied identity; who are you, when you can wear any face?
Link: AI: Artificial Intelligence
Link: AI - Artificial Intelligence: Index of Stills