Cessna 210 Cracked Nose Gear Torque Link A repair station has replaced several upper torque links after finding them bent at inspection (approximately five have been found). Only one was found cracked. The submitter believes landing impact with more than the recommended strut extension (five inches maximum), according to the service manual. Strut extension is adjusted by adding shims (p/n 1243618-2.) Part Total Time: 4609.2 hours Diamond DA42 Unsecured Downlock Pin The circlip (p/n: DIN471-8-ZP) securing the downlock pin in the main landing gear legs has repeatedly twisted off. One aircrafts aft wheel well was damaged due to the pin hanging halfway out and coming into contact with the surrounding laminate structure. The submitter suggests the pin should be secured with something that is permanent, like a cotter pin or safety wire. Part Total Time: (unknown) ECI Cylinders Cracked Cylinder Head The Beech A36s pilot reported severe vibration. Inspection discovered the spinner bulkhead was severely cracked. Further inspection found the number one cylinder to be cracked all around its circumference at the ninth and tenth cooling fins. During disassembly, the cylinder assembly came off in two pieces. The crack was severe, (moving completely through) the cylinder walls where the cylinder bore and the combustion chamber meet. AD 2004-8-10 does not apply to this cylinder. However, ECIs Mandatory Service Bulletin 06-2 does identify this cylinder for crack inspection. Part Total Time: 355.0 hours Champion Oil Filter CH48110-1 Filter Element Separation A new filter was installed on the Lycoming O-235 engine installed in a Cessna 152 during an oil change. On the first flight afterward, the pilot noticed dropping oil pressure and high oil temperature, and returned to land. Investigation found filter element debris under the pressure relief valve, causing low oil pressure. A second filter of the same date code was found to have loose debris in the filtered side of the filter element, and the element (itself) was bonded only on one end. The engines oil passages were flushed with air; several pieces of debris were found. A new filter of different date code was installed, followed by several ground runs. A new filter from a different manufacturer was installed and the engine released for flight. Part Total Time: 1.0 hours