On July 16, 2003, approximately 1615 Pacific daylight time, a tail wheel equipped Andelin (Pitts) S1E experimental aircraft, N732E, registered to and being flown by an airline transport rated pilot, sustained substantial damage during a loss of control and nose down event during the landing roll at the Portland-Troutdale airport, Troutdale, Oregon. The pilot was uninjured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was personal, was operated under 14 CFR 91, and originated from Troutdale, earlier in the afternoon. The pilot reported that after a local flight he returned and set up for an approach to runway 25 at he Troutdale airport. He made a 3-point touchdown and as the aircraft decelerated through about 40 miles per hour the aircraft began to drift right of centerline. The pilot reported that he applied left rudder but the aircraft continued to the right at which time he applied left brake. The aircraft's lower left wingtip contacted the runway. The aircraft decelerated to a stop coming to rest on its nose and right wingtip. The pilot reported that the Troutdale air traffic control tower advised of variable winds at six knots. The 1653 surface weather observation taken at Troutdale airport reported winds as variable at three knots. Post-crash examination of the aircraft's braking system revealed a piece of hose lining material within the left brake line at the caliper fitting which completely obstructed the left brake line (refer to Attachment M-I and photograph 1).