Incident on 21 April 2018
On 21 April 2018 at 07:10 local time, a Bombardier Learjet 60 departed from Modlin Airport (EPMO) en route to Zurich Airport (LSZH). While cruising at flight level FL400, the crew experienced a cabin decompression. They followed the standard operating procedures as outlined in the Aircraft Flight Manual and the operator's Operational Manual. The crew decided to abort the flight and return to Modlin, where a safe landing was performed without exceeding any aircraft limits. The details of the event and the decisions made by the crew, as well as the work performed by the maintenance station, were described in the operator's final report dated 15 June 2018.
Incident on 8 May 2018
After maintenance that included incorporation of Bombardier Service Bulletin SB 60-21-16 Rev. 2, the aircraft completed a technical flight to FL450 and was deemed airworthy. Four flight segments were subsequently flown, three with a different captain not involved in the previous event. On 8 May 2018 at 16:30 local time, during a flight from Modlin to Geneva Airport (LSGG), while descending from FL410, the crew heard a loud bang from the rear of the cabin and observed a rapid increase in differential cabin pressure. The crew donned oxygen masks and performed the cabin decompression procedure from the Quick Reference Handbook. The aircraft continued at FL200, and on instruction from Rhein Radar air traffic control, the crew set the transponder to Squawk 7700. The flight to Geneva was completed with the crew wearing oxygen masks, and a safe landing was executed. The operator, CAMO department, and maintenance stations were notified. The event details were again documented in the operator's final report dated 15 June 2018.
Cause
The investigation determined the probable cause to be a failure of the vacuum line, resulting in a loss of pressurization system integrity.
Preventive Actions
In response, the operator repeated the application of Bombardier Service Bulletin SB 60-21-16 Rev. 2, dated 5 June 2017. The Polish State Commission for Accident Investigation (PKBWL) did not issue any safety recommendations.