Date: 201704
Local time of day: 1801-2400
Light: Night
Aircraft: B737-900
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Horizontal Stabilizer
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Communication Breakdown; Time Pressure
Second reporter function: Technician
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Routine Inspection
Result: Aircraft Aircraft Damaged; General Maintenance Action
Contributing factors: Procedure; Manuals; Human Factors
Primary problem: Human Factors

Narrative: I stopped to see if the technician working the aircraft on the gate needed help. I had overheard a radio call about a dent on the left horizontal stabilizer. I also heard the Supervisor say the damage was old and had been archived. When I arrived at the gate; several technicians were looking at the damage. The general consensus was it was new damage and needed to be addressed. The Base Maintenance was notified on the radio that we needed 30 minutes to evaluate the damage. At that time the Supervisor made a radio call to the Base Maintenance and said the damage had been archived; the aircraft was released and ready to go. The technician working the gate wanted to create a logbook entry and called the shift manager to inform him. The shift manager informed him that based on the information he had received from his Supervisor; the damage had been addressed and was good to go. The Supervisor was also reported as telling another technician that felt the damage was out of limits that he didn't know what he was talking about.I believe the technician working the gate was placed under unreasonable pressure by management not to make a logbook entry. Prior the aircraft departing I took several photographs of the damage and showed them to the shift manager and the Supervisor. The shift manager informed me that he had contacted Maintenance Control at the arrival airport to investigate the damage when the aircraft arrived. He requested that I send him the photos that I had taken so he could send them to Maintenance Control. The Supervisor told me that after seeing the photos that he had called the control center and attempted to stop the aircraft from departing but was too late. This all took place within minutes of departure time and the aircraft was allowed to depart to ZZZ1.As of the next morning; I checked for a log or entry in maintenance software regarding the damage but found none. I found the aircraft had been dispatched to ZZZ2 and was about to depart for [an international flight]. At which time I attempted to contact the shift manager on duty without success. I then contacted the hangar Supervisor who contacted Maintenance Control and the shift manager. The aircraft was taken out of service in ZZZ2.


Second narrative: [Report narrative contained no additional information.]


Synopsis: Maintenance Technicians reported that a B737 was allowed to continue in service before it could be determined if a dent was within limits.