On July 8, 1996, approximately 1230 Pacific daylight time, a Piper PA-46-350P, N58VJ, operated by DMH Inc., was observed to have damage to both wings while on the ramp at the Hillsboro airport, Hillsboro, OR. Visual meteorological conditions prevailed. The private pilot and four passengers were not injured. The 14 CFR 91 personal flight had departed Sun River, OR earlier in the day for Hillsboro. During landing at Hillsboro, the pilot heard a "popping" sound. After taxiing to the ramp, line service personnel noticed the wings of the aircraft were wrinkled and collapsed in the fuel tank area. Black electrical tape was later discovered over both wing fuel vents. Determination of substantial damage was not made until 7/25/96, when it was determined that the outer sections of both wings would need to be replaced. The time of the actual wing collapse and the source of the tape was not determined.