Narrative:

While performing gate maintenance duties in the morning; I was [also] tasked with shuttling two employees back to the hangar after they delivered a routine overnight (ron) aircraft to the gate at approximately xa:45 hours. While dropping the two off at the hangar; I was contacted by the on-duty supervisor and advised that avionics technician Y would be accompanying me back to the gate; due to a maintenance problem with aircraft X.on arrival at the gate at approximately xa:55 hours; the pilot in command (PIC) of aircraft X advised that the beta lockout system would not test. After contacting ZZZ1 maintenance control; we agreed to remove the forward left pressure panel and verify that the toggle switches associated with the system were in the 'normal' position. Avionics technician Y and I removed the panel. Technician Y returned the toggle switches to the 'normal' position. The PIC re-tested the system and he related in substance that the system was testing properly. As technician Y began to re-install the panel removed; I contacted ZZZ1 maintenance control to report our maintenance action and complete the logbook entry as directed by ZZZ1 maintenance control.after completing the logbook entry; I exited the aircraft where I immediately went forward and conducted a hasty exam of the panel removed and the dc contactor bay door above it; which had been opened in order to ensure they were secure. The door was closed and latches secured and the panel was flush and there were no apparent unfastened screws raised out of their holes. Feeling satisfied that technician Y and I had done the best job possible; working in the extreme cold; I cleared the scene at approximately xb:40 hours.later that day; at approximately xc:30 hours; while on duty at ZZZ maintenance base; I was approached by technician Y and he told me that he had failed to install two screws in the panel removed on aircraft X earlier that day. He told me that he had found two screws in his pocket after he returned from gate duty.as I was checking behind technician Y and performing a hasty exam of the doors and panels; I did not devote the proper amount of time and attention to verify that all of the screws were in their places. Even after bending over to look past the curvature of the airframe; I still missed the two (2) fasteners. Technician Y reported the event to the on-duty supervisor and a check of the aircraft after arriving in ZZZ2 revealed two missing fasteners on the panel.I am certainly going to be more careful in the future about storing hardware. I have already placed a stash of parts bags in the maintenance van for use when removing panels in the future. I will communicate more frequently during the task with coworkers involved to ensure we are doing what we can in a safe and complete manner. I will encourage open discussion and cultivate a work environment which promotes free exchange of suggestions for good work practices during maintenance actions to ensure we are cross-checking each other to prevent oversights like mine.

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Original NASA ASRS Text

Title: Two Technicians describe their involvement with reinstalling a forward left pressure panel (121AL) on a DHC-8-300 aircraft; after checking the toggle switches associated with the Beta Lockout System. Two screws used to secure the panel were not reinstalled.

Narrative: While performing gate maintenance duties in the morning; I was [also] tasked with shuttling two employees back to the hangar after they delivered a Routine Overnight (RON) aircraft to the gate at approximately XA:45 hours. While dropping the two off at the hangar; I was contacted by the On-Duty Supervisor and advised that Avionics Technician Y would be accompanying me back to the gate; due to a maintenance problem with Aircraft X.On arrival at the gate at approximately XA:55 hours; the Pilot in Command (PIC) of Aircraft X advised that the Beta Lockout System would not test. After contacting ZZZ1 Maintenance Control; we agreed to remove the forward left pressure panel and verify that the toggle switches associated with the system were in the 'normal' position. Avionics Technician Y and I removed the panel. Technician Y returned the toggle switches to the 'normal' position. The PIC re-tested the system and he related in substance that the system was testing properly. As Technician Y began to re-install the panel removed; I contacted ZZZ1 Maintenance Control to report our Maintenance action and complete the logbook entry as directed by ZZZ1 Maintenance Control.After completing the logbook entry; I exited the aircraft where I immediately went forward and conducted a hasty exam of the panel removed and the DC contactor bay door above it; which had been opened in order to ensure they were secure. The door was closed and latches secured and the panel was flush and there were no apparent unfastened screws raised out of their holes. Feeling satisfied that Technician Y and I had done the best job possible; working in the extreme cold; I cleared the scene at approximately XB:40 hours.Later that day; at approximately XC:30 hours; while on duty at ZZZ Maintenance Base; I was approached by Technician Y and he told me that he had failed to install two screws in the panel removed on Aircraft X earlier that day. He told me that he had found two screws in his pocket after he returned from gate duty.As I was checking behind Technician Y and performing a hasty exam of the doors and panels; I did not devote the proper amount of time and attention to verify that all of the screws were in their places. Even after bending over to look past the curvature of the airframe; I still missed the two (2) fasteners. Technician Y reported the event to the On-Duty Supervisor and a check of the aircraft after arriving in ZZZ2 revealed two missing fasteners on the panel.I am certainly going to be more careful in the future about storing hardware. I have already placed a stash of parts bags in the Maintenance van for use when removing panels in the future. I will communicate more frequently during the task with coworkers involved to ensure we are doing what we can in a safe and complete manner. I will encourage open discussion and cultivate a work environment which promotes free exchange of suggestions for good work practices during maintenance actions to ensure we are cross-checking each other to prevent oversights like mine.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.