What happened
Two distinct incidents occurred involving a Bombardier Learjet 60 operated by AMC Aviation. The first event took place on April 21, 2018, during a flight from Modlin (EPMO) to Zurich (LSZH). While cruising at FL400, the aircraft experienced a cabin depressurization. The crew followed standard operating procedures, the aircraft's AFM, and the operator's instructions, ultimately deciding to abort the flight and return to Modlin. The landing was completed without exceeding the aircraft's structural limits.
Between April 23 and April 28, 2018, maintenance was performed on the aircraft, incorporating manufacturer recommendations from Bombardier Inc. Following these repairs, a test flight was conducted up to FL450, which confirmed the aircraft's airworthiness. The aircraft subsequently completed four flight segments, including three with a different captain.
On May 8, 2018, a second incident occurred during a flight from Modlin (EPMO) to Geneva (LSGG). While descending from FL410 toward landing, the crew heard a loud bang from the rear of the cabin and observed a rapid increase in differential pressure on the cockpit instruments. The crew immediately donned oxygen masks and executed the Quick Reference Handbook (QRH) procedures for cabin depressurization. The flight continued at FL200, and the crew set the transponder to Squawk 7700 as instructed by Rhein Radar. The aircraft landed safely at Geneva (LSGG) while the crew remained on oxygen.
The investigation
The investigation, conducted by the PKBWL and AMC Aviation, focused on the mechanical integrity of the aircraft's pressure system. The investigators examined the maintenance records following the first incident, the results of the subsequent test flight, and the operational responses of the crew during both events.