I just encountered a Brodmann BG-187 with separated beams:
It could be a result of a drop. Looks like glue joint failure. Have you checked the plate, soundboard, case for signs of cracks and finish damage ?Was the piano moved recently ?
Yes, it was moved recently. It was bought from a private sale 1,000 km away. This is the first time I have seen the piano, so I have no idea how long it's been like this. No other damage that I can see.
James K made some good suggestions. If all that looks good and the piano sounds and plays as well as it should, then it is likely just fine enough. If not dropped and damaged in that way, likely just put together at the factory in a manner that left quite a bit of stress on the beams and they separated. One could always squish a bunch of epoxy into the crack and call it done - or - just leave it and call it not a problem.
You left out information. Is it up to pitch? If it hasn't been tuned recently is it at least even?
No concerns about pitch - it was fairly close and even.
No, it came from the Vancouver area, a mild west-coast climate. It'll be in a severe climate up here though. It's only been here for a few weeks, so I don't think it would have separated since arriving, but I suppose that's possible. It does have a Piano Lifesaver System installed.
Warn them and keep an eye on it. Years ago I serviced an old Weber grand with a crack in the middle plate strut. Marked its length and warned the client. 10 years later hadn't changed.
I've had similar experience to Larry. Wouldn't worry about something you can't really fix. Record measurement of crack and write date. Check it every time tuned. If it stays the same for two years it will probably stay that way for twenty more.
Peter Grey Piano Doctor