As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING GROUND RETRACTION TESTS, THE GEAR FAILED TO RETRACT. HYDRAULIC PRESSURE CLIMBED SUFFICIENTLY TO TRIP PNEUMATIC BLOWDOWN SYSTEM. PROBLEM TRACED TO CHECK VALVE WHICH ALLOWED HYDRAULIC PRESSURE TO BE APPLIED TO GEAR UP, GEAR DOWN AND PNEUMATIC BLOWDOWN SYSTEM SIMULTANEOUSLY. DISASSEMBLY OF VALVE REVEALED CONTAMINATION WHICH APPEARED TO BE A SMALL PIECE OF O-RING MATERIAL.