Failure Files

On January 5, 2024, a Boeing 737 MAX 9 door plug blew out mid-flight because four retention bolts were never reinstalled after a factory rework procedure. The NTSB published its final report in June 2025. Here is what every maintenance professional and fleet manager should take away from this incident.

An NTSB investigation confirmed that a single undertorqued connecting rod bolt caused a catastrophic engine failure and fire aboard the Washington State Ferry Wenatchee in 2021, resulting in $3.8 million in damage. Here is what went wrong, and why torque is a fastener specification — not an afterthought.