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                           BULLETIN
        FSB-115 - WORKHORSE ADCP PRESSURE SENSOR PROBLEM
                    DATE/REV:  01DEC97 / 0
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ABSTRACT: Workhorse ADCPs with a pressure sensor installed in the
transducer before 01OCT97 may have corrosion or leakage problems.

INSTRUMENT/PROGRAM AFFECTED:  All Workhorse ADCPs with a pressure
sensor installed in the transducer before 1 October 1997.

DESCRIPTION:  The original design of the WH pressure sensor used
silicone oil to isolate the sensor from the water. This design
does not adequately keep the oil in place. The seal protecting
the pressure sensor does not work properly, which can allow water
to come in contact with the sensor. Water will damage the sensor,
and if allowed to corrode, can cause flooding of the WH ADCP.

SOLUTION/ACTION:

Long-Term:  RDI has a new design that prevents water from coming
into contact with the sensor. The design repair cannot be done in
the field. The ADCP must be returned to RDI for this repair. If
you currently have a WH pressure sensor that was delivered to you
before 01OCT97, please contact RDI to schedule a time to return
the system and have the sensor upgraded. Please note that the
upgrade will take a minimum of three weeks to perform.

Short-Term:  If you must use your ADCP before the repair can be
done, we do not know of a way to prevent the sensor from getting
water against the pressure sensor.

If you intend to do short deployments (e.g.; less than 30 days),
and you are NOT in an area known for high corrosion, you can
place fresh silicone oil inside the cavity just before your
deployment. The oil will not remain in place, but it does provide
some protection for this period of time. Note that prolonged
exposure to water will cause failure and corrosion of the sensor.
If the corrosion becomes severe, the system will flood.

If you intend to do longer deployments, we suggest that you plug
the pressure sensor. The sensor data will no longer be valid, but
the ADCP can still be used. If you do use the ADCP in this
fashion, be sure to manually edit your *.cmd file to change the
EZ command from EZ1111111 to EZ1011111. This will turn off the
use of the pressure sensor in calculating the speed of sound.

We apologize for the inconvenience this may cause you.
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