The National Transportation Safety Board says Boeing warned plane owners in 2011 about a flaw in the part that failed and contributed to the engine flying off a UPS plane before it crashed and killed 15 in November but at that point the plane manufacturer didn’t believe it threatened safety.

Boeing warned plane owners in 2011 about a broken part that contributed to last year's UPS cargo plane crash that killed 15 people, but at that time the plane manufacturer didn't believe it threatened safety,

The NTSB said Boeing previously warned plane owners in 2011 about a flawed part and that it contributed to the engine flying off a UPS plane before it crashed.

The Hawaii-bound cargo plane crashed on Nov. 4 just after takeoff in Louisville, Kentucky. #AviationSafety #NTSB #UPS

An update on last fall's deadly UPS jet crash has raised questions over past warnings and returned focus to Boeing's rocky record of safety in recent years.

LOUISVILLE, Ky. (WDRB) -- More than two months after a UPS cargo plane crashed in Louisville, killing 15 people, cleanup continues at the crash site as families search for closure. For the first time, the media was allowed inside the site, where much of the debris has been cleared but visible reminders of the tragedy remain.