The Reuters news agency reported on October 24, that a software change within the engine control box could be the reason for three recent engine inflight shutdowns on Swiss’ (LX/SWR) Airbus A220 aircraft. In its first reaction after the third engine failure resulting in a diversion, the Swiss national airline halted its fleet of Airbus A220 jets for more than a day on October 15. As the affected engine, the PW1500G, is manufactured by US company Pratt & Whitney, the investigation into the occurrences is led by the NTSB. The team is currently investigating whether a software change allowed for unexpected vibrations that damaged parts, several people familiar with the case said. Due to a recently revised software release, parts in the engine could possibly be tuned to cause mechanical resonance or destructive vibrations. Airbus and Pratt & Whitney, therefore, recommend setting the engine thrust setting to a maximum of 95% when flying above 29,000 feet. This demanding configuration is currently only required by Swiss, being the only affected operator of the Airbus A220 with this failure so far. The larger Airbus A320neo family, as well as the new Embraer E2 series, Irkut MC-21 and the Mitsubishi SpaceJet, are all powered by the PW1000 family, to which the PW1500G belongs to, but their engines are not affected by the revised software. Swiss reported first problems with the engine shortly after the new software update was applied, mostly on flights between Geneva and London. One of the three engine inflight shutdowns was called a “uncontained” engine failure, as compressor debris punched a hole in the engine casing. In the most recent event, which led to the temporary grounding of the Swiss A220 fleet, engine parts escaped from the back of the engine. The French BEA, therefore, decided to ask for about 150 volunteers to find a titanium part from the engine in the woods in eastern France. Pratt & Whitney is now working on a new version of the software to allow the flight restrictions to be lifted, but it is not expected to be ready before the first quarter of 2020. However, the main cause for the issue has not yet been confirmed and it is unclear if this software can result in other potentially dangerous scenarios, too. So far, neither Airbus nor the NTSB has commented on the investigation. The European Union Aviation Safety Agency (EASA) is monitoring the situation closely and coordinating the steps with the FAA. United Technologies, the parent company of Pratt & Whitney, is working on finding the route cause of the failures and remained confident in the new engine type. “Clearly, any time you get an issue like this, we’re on top of it. The guys are working through it,” Chief Executive Greg Hayes told analysts on a conference call.