What happened
Following a wheel landing, the pilot reported that the aircraft drifted to the right of the runway centerline toward the south. Despite the application of brakes and other corrective actions, the aircraft continued off the runway and descended down an embankment running parallel to the runway. During the excursion, the main gear separated from the airframe, which caused substantial damage to the fuselage.
The investigation
A visual inspection of the aircraft was performed by an FAA inspector from the Seattle, Washington, Flight Standards District Office (FSDO). The inspection revealed no evidence of brake failure or mechanical malfunction.
Weather conditions at the time of the accident were noted by a San Juan County Sheriff's Deputy, who estimated winds at Roche Harbor were blowing at 10-15 knots at a 30-40 degree angle relative to the runway, favoring runway 24. Additionally, a METAR observation from Friday Harbor, Washington, recorded at 1553, indicated winds from 230 degrees true at 7 knots.