Weather, engine failure, even sabotage among many theories

          Whatever happened on Kenya Airways Flight 507 that caused the new Boeing 737-800 to crash in an African jungle over the weekend could open a new chapter in jetliner accident investigations. If the crash turns out to have been caused by mechanical failure, it would be the first involving several newer jetliner models from The Boeing Co. and Airbus that have exceptional safety records. But the accident also could have been weather-related, pilot error or even sabotage, an aviation expert said.
          So far, there are only questions about why the plane went down shortly after taking off Saturday from Douala in the West African nation of Cameroon. It was headed for Nairobi. All 105 passengers and nine crew members were killed. "At this point, it's a smoking-hole mystery," said John Nance of Tacoma, a former 737 pilot, author and aviation safety consultant for ABC news. "We know we have lost one. We have no idea why."
          He discounted news reports from the scene that the plane may have lost power in both engines while flying through a storm. Whatever the cause turns out to be, it is hardly the kind of jetliner crash that for years has raised concerns about aviation safety in Africa. Typically, those accidents involved old jets operated by airlines with questionable maintenance and safety records. Kenya Airways is highly regarded. It is experiencing phenomenal growth and has been moving aggressively to modernize its fleet. The airline was the first in sub-Saharan Africa to operate Boeing 777s and has ordered nine of Boeing's 787 Dreamliners.