What happened
On December 22, 2015, an Embraer E170 operating within the Warsaw (EPWA) control zone experienced a technical malfunction involving the aircraft's cabin pressurization system shortly after takeoff. Upon detecting the issue, the flight crew decided to abort the flight and return to Warsaw Chopin Airport. The crew did not declare an emergency during the diversion, and following a safe landing, an Air Safety Report (ASR) was filed regarding the incident.
The investigation
The investigation focused on the failure of previous maintenance efforts to resolve the pressurization issue. It was established that several prior repair attempts had been unsuccessful in permanently fixing the fault. During ground testing, the specific error could not be replicated; however, subsequent data analysis on February 7, 2016, revealed persistent error logs related to loop #5. This indicated that, in addition to a confirmed leak in the line exiting the precooler, there was likely a leak within the precooler seal itself or potential damage to the unit.
Findings
- The primary cause of the incident was a leak within the precooler (P/N 1002165-3).
- Previous maintenance actions were ineffective at resolving the underlying leakage.
- The issue was ultimately resolved following the replacement of the precooler unit, after which subsequent flight data showed no further