Regional Jet 900 (CRJ900)
Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
General Maintenance Action
Procedure; Human Factors; Aircraft
Maintenance crew went over to the gate to bring it back to the hangar and noticed hydraulic fluid dripping off of the tail section of the aircraft. It was running down from the APU bay area to the door to the aft equipment bay. They also noticed the hydraulic level was 25%. Level was serviced before taxi. On way to hangar level dropped 15%. Gained access to the aft equipment bay to look for leaks. Noted that the aft bay was filled with fluid on the right hand side. Checked into [inventory] for maintenance history regarding hydraulics and flight controls. Noted aircraft had a couple for write ups for low pressure and had maintenance done on it with replacing a couple of switches; Job Card X and Job Card Y according to [inventory]. Upon further inspection; found the cause of the leak to be coming from Job Card Z. After removal of switch; it was found to be installed with no O-ring; the back shell to the connector was not tight and the switch was not safetied. The sign off and reference used was also incorrect. Job Cards X/Y is for the Number 1 system; not the Number 2 system which was the write up that was being worked by [a Technician]. There is no AMM (Aviation Maintenance Manual) 29-XX-XX. It was also found that the top switch; Job Card Z was also not safetied; but did have an O-ring installed.I did go back into aircraft in the Maintenance Control screen and saw that [the aircraft] was worked on by a road trip. I would have to guess that lack of manuals and knowledge played a part in the errors committed.
CRJ-900 Maintenance Supervisor reported that the aircraft was losing hydraulic fluid due to a switch that was installed without an 'O' ring.