Dozy,
t took almost ten years, a time during which Boeing submitted their own internal report to the FAA which blamed the pilots of UA535 for the crash. The PCU design was such that it could affect any of the 737s in the air at any time between 1967 and 2002.
and
But that's exactly what happened with the 737 hardovers, and the aircraft was left flying with a known fault for nearly ten years.
If you are going to tell a story and represent it as fact, you need to tell the whole story.
The NTSB investigated the UA 535 accident for nearly 2 years and
could not confirm the cause of the crash in their report issued in 1992. In September 1994, USAir 427 crashed in Pittsburgh. The NTSB investigated this accident for 4 1/2 years before concluding a rudder malfunction was to blame. The final report was written by the NTSB in 1999. The NTSB concluded part of the problem and cause was lack of reliable redundancy in the rudder control system. The NTSB also blamed the FAA for dragging its feet on implementing enhanced flight data recording capabilities on Boeing 737s, which hampered the investigations.
Subsequently, the NTSB went back and revised the UA 535 final report in 2001. The three NTSB reports can be found here to refresh your memory:
http://libraryonline.erau.edu/online...s/AAR92-06.pdf
http://www.ntsb.gov/doclib/reports/1999/AAR9901.pdf
http://www.ntsb.gov/doclib/reports/2001/AAR0101.pdf
These are the reports that count. Can you provide a link to Boeing internal report you cited?
Keep in mind, today there is a lot more data recorded, some realtime, than there was 20+ years ago and therefore addressing a problem becomes possible in a shorter time frame.