HMCS Chicoutimi receives integral maintenance to Bow Sonar Array

Ashley Evans
FMFCB
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In February, a team of electronics technicians in Fleet Maintenance Facility Cape Breton Sonar Shop 153, along with the Quality Control team, were tasked with maintenance and repair work on HMCS Chicoutimi’s bow sonar array.

Sonars are essentially the eyes of a submarine when it is underwater, and the Bow Sonar Array is the largest part of its sonar system.  The sonar system comprises both active and passive elements that include a 96-stave, cylindrical bow array plus flank arrays. The system can track multiple contacts simultaneously. 

The array was previously part of the original Type 2040 Sonar system but will now be used in conjunction with the BQQ-10 Sonar system, an upgrade the submarine will receive during the ongoing transitional docking work period. 

Throughout 1,600 work hours, the eight-person team rebuilt the underwater connectors, manufactured specialty cables, and reconditioned transducers for this system.

They also tested each hydrophone, an acoustic instrument found on the sonar staves. Typically, there are four or eight hydrophones on each stave. Because the submarine supply system has an abundance of staves, the team were particular with the ones they refurbished or replaced.

The testing procedure was a two-step process. First was an underwater check for leaks, done by submerging the body and checking the staves resistance to electrical current flowing from the internal wires into the surrounding water, otherwise known as a megger test. If water gets in, current will flow out, explained Mike Quinn, Shop 153A Sonar.

Next, a functional test was done to ensure all hydrophone elements in the stave worked. Technicians put a noise source on each hydrophone and checked that a specified signal came out. If the stave was suitable, they cut the old connector off and replaced it with a new one.

The connector body was then filled with an epoxy to secure it in place, and ensure it can withstand the crushing water pressure it will be subjected to through normal operations of the submarine. Once the epoxy cured, the connector body was painstakingly prepped for final water proofing.

Lastly, a glue-filled plastic sleeve called a heat shrink was slid over the connector and heated to the appropriate temperature for about 10 minutes. Once cooled, the glue prevents water from entering the connector.

The suitability tests were then repeated, this time with the stave body and connector submerged in a special pressure vessel that replicates the diving pressures of the submarine.

Quinn says the most challenging part of this project was quality control as only a few sonar technicians have ever assembled these particular connectors. Due to the nature of the project, with the numerous technical details that must be executed properly for the watertight seal to be effective under pressure, there was quite a bit of going back and remaking parts.

“Looking at the quantity of finished product completed to a high standard feels pretty good,” says Quinn.

In total, 175 patch cables were manufactured from scratch and tested. Additionally, 96 staves were connectorized and tested.

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