Maintenance Powerplant; Maintenance Airframe
Troubleshooting; Situational Awareness; Communication Breakdown; Distraction
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft Aircraft Damaged; General Flight Cancelled / Delayed; General Maintenance Action
Chart Or Publication; Human Factors; Manuals; Aircraft; Procedure
Aircraft Maintenance Technician (AMT) and I were working on checking the adjustment of the door warning targets reference Aircraft Maintenance Manual (M/M) 32-61-32; per paperwork we installed [landing] gear pins and body gear door lock.  Due to hangar bay-3 APU run procedures; we had to stop work and push back plane out of the hangar.  After that; we started the rig check of [proximity] sensor which required to close right wing gear door and check gaps and remove body gear door lock before closing of [right wing gear] door per Maintenance Manual (M/M) 32-00-30 201.  I forgot to remove the [body gear door] lock due to distraction of moving aircraft which resulted in right wing gear door making contact with body gear door lock.
While accomplishing the adjustment of the right wing gear door proximity sensor; reference Maintenance Manual (M/M) 32-61-32; we installed body gear door lock to gain access to upper side of wing door.  In order to raise gear doors; hydraulic system -1 and -4 need to be pressurized which requires the APU to be run.  After repositioning the aircraft to run the APU in the hangar; due to local policy; we then continued our job of checking the sensor adjustment.  When [right wing] gear door was raised and then lowered; damage to aft edge [of right wing door] was noticed due to contact with body gear door lock.  Time constraint was an issue due to aircraft on XB:30pm [departure] routing and XA:00am due on gate time.
Two line mechanics report a B747-400 right wing gear door trailing edge was damaged after making contact with the right wing body gear door lock.  Mechanics were checking the adjustments of the landing gear door proximity warning targets.