Red Hot Chili Peppers fansite, news page and forum with dedicated RHCP magazine scan and articles section featuring Anthony Kiedis, Chad Smith, Flea Michael Balzary, Josh Klinghoffer and John Frusciante.
Flea posted this photo showing his arm in a sling on 17th February, 2015. Both Flea and Chad had been posting showing them skiing and given the snowy background in this photo, it seems a fair guess to assume that the injury was winter sports related.