As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON A ROUTINE TRAINING FLIGHT, IT WAS NOTED BY THE CREW THAT THE LANDING GEAR POWER PACK WAS CYCLING APPROXIMATELY EVERY 30 SECONDS. MAINTENANCE INSPECTION REVIELED THAT THE O-RING ON THE CHECK VALVE HAD FAILED P/N MS28775-016. O-RING WAS REMOVED AND REPLACED WITH NEW O-RING. NO FURTHER INCIDENT WAS NOTED.