Overview
On December 22, 2015, an Embraer E170 aircraft was involved in an incident during a flight departing from Warsaw Chopin Airport (EPWA). The flight crew reported a technical problem with cabin pressurization shortly after takeoff. The aircraft returned to EPWA, and the crew did not declare an emergency. After landing, the crew filed an Air Safety Report (ASR). The incident was linked to a separate occurrence under investigation (incident number 2631/15).
Sequence of Events
After takeoff, a cabin pressurization issue was identified. The decision was made to return to EPWA. The crew did not indicate any distress. The landing was uneventful, and the subsequent report led to a technical investigation by the aircraft operator.
Investigation and Cause
The investigation determined that the underlying cause of the pressurization problem was a leak in the Precooler (part number 1002165-3). The troubleshooting process revealed that earlier repair actions had been ineffective. During ground tests, the fault could not be reproduced. Subsequent data downloads on February 7, 2016, indicated a persistent error code for loop #5, suggesting a leak not only in the pipe from the precooler but also likely from the precooler seal or the unit itself. A replacement of the precooler was ordered.
Corrective Actions
Following the replacement of the precooler, no further bleed leak indications were recorded. Data from the Flight History Data Bank (FHDB) after two initial sectors showed no loop errors or overheat warnings. After ten additional sectors, no errors were present. The aircraft continued to be monitored under routine surveillance. The final corrective action—replacement of the precooler—proved successful, as the BLEED 2 LEAK fault did not recur. An Engineering Reliability Report was prepared by the operator's engineer, documenting the troubleshooting, tests, component replacements, and probable causes.
The investigation committee did not issue any safety recommendations regarding this incident.