Email Boeing 777 grounding explained visually: Pratt and Whitney engine failure involved in two incidents on same day Two Boeing planes dropped engine parts on Saturday. Same engine manufacturer as past events. NTSB eyes fan blades cited in 'scary' 2018 United flight. George Petras and Janet Loehrke, USA TODAY Published 7:13 pm UTC Feb. 24, 2021 Air safety officials are focusing on engine fan blades in their investigation of what caused a massive engine failure aboard a Boeing 777-222 commercial airliner Saturday, strewing huge aircraft parts across neighborhoods in suburban Denver. This engine failure may be related to several others stretching back for years, but first let's review the details of the most recent event.