Removing trapped air from the installation trunk (CS90)
Once the vessel is set afloat after the CS90 installation, the installation trunk will contain trapped air. During normal use, the installation trunk will be filled with air due to the laminar flow and the air bubble in the water. Trapped air in combination with the salt water may lead to problems with rust inside the installation trunk. If you have installed the optional gate valve, use this procedure to remove trapped air from the transducer dock. Note that this task is only relevant for the CS90 Hull Unit.
Prerequisites
Image
The following specific tool is required for this task:
•  Spanner (US: Wrench) (19 mm)
Context
The top of the mounting flange offers a small air vent screw. This is a specially designed screw. It contains vents that channel the air out of the installation trunk. A few turns on this screw will allow the air to be released.
Note
Do not remove the screw completely!
We suggest that you to implement this pressure release task as a part of the preventive maintenance program for the CS90.
Procedure
1 Locate the air vent screw.
2 Use a spanner to carefully loosen the screw.
Note
Do not remove the screw completely!
3 Stop when air or water escapes.
4 Keep the screw loose (open) until water is leaking out.
5 Close the air vent screw firmly.