On May 29, 2018 about 0900 Pacific daylight time, a Cessna P210, N7546K, was substantially damaged when it was involved in an accident near Lewiston, Idaho. The private pilot, the sole occupant, was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, following departure, he climbed to his planned enroute altitude of 7,500 ft mean sea level. He noticed that the airspeed was lower than expected and then saw that the landing gear position indicator light showed that the gear was not retracted. The pilot cycled the gear but was unable to fully extend or retract them. He then attempted to manually lower the landing gear with the emergency hand pump but was unsuccessful. He declared an emergency and subsequently landed with the gear retracted, resulting in substantial damage to the horizontal stabilizer spar. Examination revealed that the rigid hydraulic line connecting the powerpack to the bulkhead had failed at the ferrule. A review of the airplane's maintenance records revealed that, on March 13, 2018, at a tachometer time of 384 hours, a maintenance facility completed a check of the landing gear. A subsequent entry, dated May 17, 2018, and about 8.6 flight hours after the previous maintenance, stated, "Landing gear inop for up/dn. Pilot report did pump gear down." The entry indicated that personnel performed troubleshooting on the source of a hydraulic fluid leak, which they determined to be at the hydraulic power pack gear system. The entry stated that the tube fitting line cracked at the flare below the ferrule, and a new line of aluminum tubing the same size and length as the failed tubing was fabricated and installed.