EMB ERJ 170/175 ER/LR
Maintenance Airframe; Maintenance Powerplant
Situational Awareness
Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Procedure; Human Factors
After replacing a cannibalized trans-cowl hydraulic line on the Inboard #2 engine; I verified that the aft core cowling latches and the #5 aft most trans cowl latch were secured. I gave the all clear to proceed with the actuation of the thrust reverser to an assisting mechanic.When the Trust Reverser (TR) was commanded to actuate; it moved 1.5 inches and stopped. A Right Hand (RH) TR reverser fail EICAS message was generated.Upon investigation; it was found that the #1; #2; #3; and #4 trans cowl latches were not closed. The RH TR half caught on the #3 trans cowl latch and caused damage to the RH TR cowl.The hydraulic line that I replaced did not require opening of the TR half's. I was unaware that they had been unlatched. There was not documentation of TR latches being unsecured.In hind sight; I should have done a better job of checking the system and general area before operationally checking the system.  I accept full responsibility for the incident and damage.  The mechanic in the cockpit was told by me that it was ok to run the hydraulics and open the TR. He was not at any way at fault in this incident.  This event was caused by my lack of awareness and failure to thoroughly check a system before actuating it. Making sure that unlatched panels and systems are properly documented. Doing a complete verification that a system is ready to use.
While accomplishing an operational check on an ERJ-175 #2 engine thrust reverser (TR); Maintenance personnel did not realize that the trans-cowl latches were not secured. The Right Hand TR half caught on the #3 trans-cowl latch and caused damage to the Right Hand TR cowl.