101.   New Jersey Transit officials said it was not immediately known whether human error or mechanical failure was to blame.

102.   No X-ray check at Concourse B can expose mechanical failure.

103.   Nor have they been able to prove any other theory of a mechanical failure.

104.   Norton stars as our unnamed narrator, a burned-out drudge for a car manufacturer who investigates fatal mechanical failures.

105.   Now, we are hearing less about bombs and missiles and more about mechanical failure.

106.   Officials have said since the day after the crash that the three possible causes are a bomb, a missile or a mechanical failure.

107.   Officials said they were looking into a number of possible causes for the crash, including a mechanical failure.

108.   NTSB investigators earlier this week acknowledged they were again refocusing on a possible mechanical failure because of the lack of evidence of a bomb.

109.   NTSB spokeswoman Shelly Hazle said investigators still have not ruled out a bomb, mechanical failure or missile as possible causes of the crash.

110.   Of those, how many can be attributed to pilot error, compared with mechanical failure?