Air China had an incident (I think it was in the late 80's) involving
a 747 bound for LA. The plane lost its outboard engine in flight, and
while the pilots were distracted with the engine shutdown checklist,
the plane slowed down as the autopilot struggled to deal with the
adverse yaw and began to pitch up and apply aileron to attempt to stay
straight and level. By the time the Captain noticed the problem, the
plane had slowed way down. The captain disengaged the autopilot and
applied rudder to straighten out of the nose, which caused a cross-
control situation and an immediate stall. The 747 abruptly snap-
rolled into a split-S, pulling over 10Gs in the process. Damage
included a twisted engine pylon, a crumpled aileron, loss of several
feet of the horizontal stabilizer, and numerous popped rivits. The
damage to the tail was symmetrical.

The pilots regained their orientation as they passed through a cloud
deck at 10,000 feet and recovered to climb back to altitude, unaware
of the extent of the damage to the plane. The controllers contacted
them to see if they were OK (due to the large and sudden altitude
excursion), and they said that they were. Asked if they wanted to
divert to San Francisco, they opted to continue to LA until they were
informed that at least one of the PAX had been injured.

Upon arrival at San Francisco, the FAA impounded the plane to conduct
an investigation, and the Boeing AOG team couldn't touch it until
after almost a month had passed while the investigation was
conducted.

The 747 does not have a G meter. They determined the G force of the
snap-roll by the fact that the flight data recorded had stopped laying
down data during the roll. Concluding that the head had pulled away
from the tape in the data recorder, they put the unit in a centrifuge
and spun it until the head pulled away from the tape at about 10Gs.

The Air China captain didn't understand what had happened until the
tapes were replayed in a simulator, at which point he was reportedly
quite shocked.

I originally heard the story from Jack Hessburg, chief mechanic on the
777 program in an air-carrier operations class that he gave at
Boeing. I also saw a segment on this incident on a TV documentary a
year or two ago...