A WestJet flight departing Toronto Pearson Airport was forced to swiftly return back to the city after facing multiple in-flight mechanical issues in an incident that would ultimately lead to the operator conducting a fleet-wide inspection. 

On March 23, a Boeing 737 MAX 8 operated by WestJet was scheduled for a trip from Pearson Airport to Calgary International Airport. 

Data from FlightAware reveals that the aircraft took off just before 4:30 p.m. and began experiencing issues shortly thereafter. 

According to the Aviation Herald, the aircraft was levelling off after departure from Toronto when the flight crew received a "hydraulic pump low-pressure indication" for the #2 engine. 

Flight path for WS4201. Photo: FlightAware

The crew diligently worked through the related checklist, and the indication was subsequently cleared. 

However, just moments later, the oil filter bypass light on the aircraft turned on, and despite trying to work through the related checklist, the issue persisted. 

#Westjet #Boeing 737-8 MAX flight #WS4201 got LOW PRESS light for HYD B engine-driven pump shortly after leveling off at FL360.
Shortly after, crew received oil filter bypass. The engine was shut down iaw the QRH and crew returned for a safe landing at Toronto.

The Canadian TSB…

— The 737 Handbook (@737handbook) March 31, 2023

The flight crew shut the engine down, and were forced to return to Toronto for a safe landing about 90 minutes after departure. The aircraft managed to land back at Pearson Airport at 5:59 p.m. 

After this incident, WestJet began a fleet-wide inspection to verify that the hydraulic quick disconnect connectors on these aircraft were all in their locked positions. 

The narrow-body airliner in question does have a complicated and controversial history.

The Boeing 737 MAX airliner was grounded worldwide between March 2019 and December 2020 in most jurisdictions, after 346 people died in two separate crashes, namely Lion Air Flight 610 and Ethiopian Airlines Flight 302. 

The aircraft suffered a repeated failure in the Maneuvering Characteristics Augmentation System (MCAS) due to a design flaw, which caused the two crashes. Canadian authorities cleared the airliner to return to service in January 2021, subject to design and training changes.