I'm pretty sure it was 2015. I was sailing in WIN at the time, and we were doing a Reassurance/Active Endeavor, so were part of the exercise as well.
That sounds about right; I think a bit before that IRO got stuck in Boston (2014?) after tripping a bunch of longitudinals from sailing into a storm that exceeded her SS limitations, which were in place to avoid exactly that kind of failure from a bunch of known cracks and other structural issues. I want to say the final nail in her coffin happened around 2016 when there was a fire in the AMR, and then when they were cleaning up a transformer fire started in the heavy workshop (basically the same compartment where they staged hoses to fight the AMR fire, but tucked away in a corner).
I was at the 280/tanker class desk at the time, so between the PRE DWP warranty claims, ATH DWP, tow, PRE allision (with the ISI floating drydock), PRO/ALG collision, PRO tow, PRE turning into an alongside fueler and some other issues a lot of it blends together, as we spent a lot of time briefing the DG and others, with a few BNs up to the MND etc. We also drafted the AJISS RFP, put together the disposal plans, and did a few other things, so learned a lot (sometimes painfully).
Not sure if it was this particular trip or a similar issue around the same time, but tracked down this old cbc story.
HMCS Athabaskan sent back to Halifax for major engine repairs
In a funny note, came across a story on the ATH DWP in St. Catherines, where the DWP costs went from $21.7M from $26.7M due to arising work, and it was seen as expensive for a 40 year old ship, going into it's last operational cycle. Probably $1M of that was 'nice to haves' like tile replacement (to check the steel deck underneath of course), replacing worn insulation and pipe lagging (can't have mold), cleaning ducting (again, mold), crew lounge repairs etc.
A decade later, we are talking about DWPs costing 20 times that for 30 year old ships, for just the same basic hull, mechanical and electrical repairs, and thinking they'll last 15 more years. Interesting.