Incident Sequence
On March 4, 2020, the crew of the Lotnicze Pogotowie Ratunkowe helicopter EC 135-P2+, registration SP-HXM, based in Szczecin, received a task for a test flight following periodic maintenance. Approximately eight minutes into the flight, the CAD monitor displayed an ENG CHIP warning for the left engine. The aircraft commander performed the chip burn-off procedure, after which the warning disappeared. About one minute later, the warning reappeared. A second burn-off procedure was successful, and the warning did not recur during the remaining five minutes of the flight.
Maintenance Findings
During the subsequent maintenance, suspicion arose regarding the possible retention of diagnostic materials used to test the chip detector and its alerting system. Personnel from the Szczecin Technical Service Station disassembled the chip detector in accordance with EMM 73-00-03, Figure 101/102. They observed minimal residues—described as burnt "hairs"—on the detector. These residues, along with diagnostic material, were sent for spectral analysis to SPECTRO, PW. The left engine oil filter was inspected and found to be free of anomalies. After receiving the analysis results, the technician (P6ZW) released the left engine for service with restrictions: the chip detector and oil filter were to be inspected after 5 and 50 flight hours.
Follow-Up Inspections
A check after 5 flight hours was performed on March 15, 2020, and a check after 50 flight hours on April 20, 2020. No abnormalities were found, and the oil filter remained clean. The helicopter was subsequently returned to normal service.