SEATTLE — Federal regulators Wednesday ordered seaplanes like the one that crashed off Whidbey Island be inspected for a flaw that likely caused the deadly September crash. The Federal Aviation Administration airworthiness directive mandates that operators of all the DHC-3 Otter seaplanes in the United States — 63 of about 160 operating worldwide — examine the stabilizer to confirm the condition of an actuator piece missing from the Friday Harbor Seaplanes aircraft that fell into Mutiny Bay over Labor Day weekend. Ten people were killed in the crash. According to the directive, operators must …