B767-300 and 300 ER
Maintenance Airframe; Maintenance Powerplant
Confusion; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Object
Aircraft Aircraft Damaged; General Maintenance Action
Human Factors; Aircraft; Procedure
After parking aircraft and setting parking brake; we shut the left engine down; then the right Eng. At that point I felt the plane rock a little and looked up and saw we had moved forward. [Aircraft departure] delay. Human Factors: Norms and Lack of Awareness.
Reporter stated he was in the Right seat watching the aircraft out of the cockpit windows and EICAS Engine display. He thought the Parking Brake was set. The Left Engine nose cowl was damaged. The B767-300 Parking Brake handle may seem engaged; but he has seen the handle move slowly away from the brake set detent in the past with the Brake handle light on. Mechanics and pilots have to really apply pressure to the brake pedals to properly set the brakes.
B767-300 aircraft was returning from performing an engine vibration survey. I was assigned to direct the taxiing mechanic to gate.  Once he arrived at its designated spot; I motioned him to set the brakes and he motioned back to me confirming for brakes set. I verified the brakes as being set by the light indication on the nose wheel. I then proceeded towards the plane to connect Ground Power Unit (GPU) and isolation pin and chocks when suddenly the plane started rolling forward until it came to rest at the crew stairs.
Three Line Aircraft Maintenance Technicians (AMT) report about a B767-300 aircraft suddenly rolling forward after the Parking Brake set signal was given to the taxi-in guide. The Left Engine nose cowl had struck a previously positioned aircraft entry stand. Concerns raised that the Parking Brake handle pawl stop pin could rest against the pawl's lip rather than within the pawl's cutout; giving a false indication of full engagement.