170.250—Types and classes.
(a)
Watertight doors, except doors between cargo spaces, are classed as follows:
(2)
Class 2—Sliding door, operated by hand gear only.
(3)
Class 3—Sliding door, operated by power and by hand gear.
(b)
The following types of watertight doors are not permitted:
(1)
A plate door secured only by bolts; and
(2)
A door required to be closed by dropping or by the action of dropping weights.
(c)
Whenever a door of a particular class is prescribed by these regulations, a door of a class bearing a higher number may be used.