On April 15, SWISS International Airlines flight LX-52, en route from Zurich to Boston, suffered an engine issue over the Atlantic Ocean and returned to Zurich.

Tracking from Flightradar24.com shows the SWISS aircraft was around 150 nautical miles northwest of Shannon, Ireland, and at 36,000 feet when the crew decided to return to Zurich. The Airbus A330-300, registration HB-JHE, landed safely at Zurich Airport (ZRH) at 22:07, just four hours after departure. Typically, the flight to Boston Logan International Airport takes around 7:40 hours.

An engine irregularity caused the turnback

Close to midnight on Monday, Simple Flying spoke to SWISS, and their spokesperson told us,

"On our flight to Boston on Saturday, the reason for the inflight return was an irregularity with the engine and the plane returned as a precautionary measure."

The spokesperson added they would look further into the matter on Tuesday and pass any available information on to Simple Flying, which we will add to the story.

The 12-year-old aircraft is powered by the Rolls-Royce Trent 772B-60 engine, one of three engines type certified for the A330-300ceo. It has proven to be the engine of choice for A330 operators and is used on more than 800 aircraft.

An engine type with more than 25 years of solid service

The Trent 772B-60 was certified in September 1997, a variant in the highly successful Trent 700 series, and with the highest in-service thrust of 71,100 ponds provides the best take-off performance for the A330-300. Its successor, the Trent 7000, is the only engine type for the A330neo.

For the A330ceo, the choices for the Trent 700 are the Pratt & Whitney PW4000 and the General Electric CF6-80E1.

The A330 platform has evolved since its maiden flight in 1992 and first commercial flight with French domestic airline Air Inter in 1994. Airbus has morphed the A330 into a smaller longer-range variant, a freighter, a military multi-role tanker, and the instantly recognizable Beluga XL transport variant.

These different aircraft put their individual demands on the engine, but according to Rolls-Royce, the Trent 700 is the only engine used on all of these A330 variants.

Since it was first certified in 1994, the Trent 700 has been a proven and reliable powerplant for the A330, so it will be interesting to learn more about the "irregularity" that prompted the pilots to return to Zurich mid-flight.

Planespotters.net data shows SWISS has 14 A330-300 out of its total fleet of 90 aircraft. The A330s have a three-class configuration of eight first, 45 business, and 183 economy seats.

Typically they are used on routes from Zurich and Geneva to ports including New York, Montreal, Boston, Chicago, Dubai, and Beijing. Other widebodies in the fleet are five Airbus A340-300 and 12 Boeing 777-300ER.

The 18-year-old A340s have recently flown routes from Zurich to Singapore, Johannesburg, Bangkok, Dubai, and Chicago. The B777s operate to Tokyo, Los Angles, San Francisco, Sao Paulo, Miami, and Shanghai (pre-lockdown). In terms of total seats, the A340 has 223, the A330 236, and the B777 340.

So far nothing has been heard from any of the passengers about how the situation was handled onboard or when they returned to Zurich. Hopefully SWISS looked after them?

Discover more aviation news here.