Just happened to me...

Here is the quote straight from the SE desk

"In the event of being involuntarily transferred to another airline not affiliated with Aeroplan, the member can request the corresponding Aeroplan Miles of the original Star Alliance ticket, provided the cancellation was due to a condition within the control of the Star Alliance carrier. This includes mechanical, crew and similar situations, but excludes circumstances beyond the airline’s control, but not limited to: weather, earthquake, fire, labour stoppages or strikes, civil unrest and closed airports. To receive credit, the member is required to send a brief description of the incident with a copy of the relevant ticket(s) and the original boarding pass(es) to the Aeroplan Centre. "