UPS plane crash: US safety board says Boeing was aware of flaw

Dhaka: Boeing had identified a structural flaw 15 years ago on its planes similar to the aircraft that crashed in Kentucky in November last year, as per reports by investigators.

Operated by UPS, an MD-11F freighter crashed after one of its engines separated from its wings as the carrier was preparing to take off from Louisville.

The plane briefly lifted off from the runway, before hurtling out of control into an industrial area, leading to 15 deaths, including three crew and 12 on ground.

The US National Transportation Safety Board (NTSB), in its latest report, revealed that cracks found in the engine mounting assembly had previously occurred on several other aircraft earlier. At that time, the American plane-maker concluded that the issue "would not result in a safety of flight condition."

NTSB’s latest update went further, describing fractures due to evidence of "fatigue" – or repeated stresses – in a critical bearing, as well as the mounting it is meant to sit in.

It pointed out that Boeing had previously found failures of the same part on four occasions, affecting three different aircraft. In 2011, the company sent a "service letter" to operators warning them of its findings. This is a non-legally-binding document used to alert operators about important safety or maintenance information.

In this case, Boeing recommended that the part be included in a general visual inspection every five years. It also pointed out changes to the inspection procedure contained in the aircraft maintenance manual, and drew attention to a revised bearing assembly that could be fitted – although this was not mandatory.

According to experts, the structure concerned is not decorative, it is an essential part of the mechanism that attaches the engine to the wing, and carries loads such as thrust and drag. It is surprising that Boeing concluded that a failure of this part would not have safety consequences.

NTSB's investigation continues, and its final report is yet to be published.