Cockpit Fire: Equipment Failure Root Cause

A cockpit fire that forced a United Airlines flight to make an emergency landing was located in a piece of window-heating equipment that was the subject of a safety warning three years ago, accident investigators said Friday.  (http://bit.ly/9s13AA)

According to the article, there have been 29 incidents with this electrical connection over the past 8 years.  Three years ago, in a letter to the FAA, the NTSB recommended that the electrical connection block be replaced.  In 2008, the FAA proposed giving the airlines the option of either inspecting the connections, or replacing the block.  That proposal has still not been approved.

Just a quick calculation shows that, with 29 failures in 8 years, we should expect an average of over 3 failures per year.  This does not take into account a change in the failure rate due to age, inspection results, etc.

Is this really just an equipment failure?  Or is there maybe some human error involved?  It’s a shame to see repeat failures with this much data available.