When United Airlines flight 232
slammed into the ground at the Sioux Falls, Iowa airport and exploded into a
huge ball of flame on July 19, 1989, it became one of the most widely witnessed
aviation disasters in history. The amateur video footage which captured and
froze in time that terrible one minute of violence quickly blossomed on home
television screens across the country and around the world; and it would be
viewed repeatedly for months and even years to come. What the general public
might at first have thought was just an emergency landing gone wrong was in
fact the inevitable consequence of a cascade of events which had begun 35
minutes earlier and 60 miles to the east when the tail-mounted and central of
the jumbo jet’s three engines exploded at 37,000 feet. In the process, all
three of the plane’s supposedly redundant hydraulic lines were severed leaving
the cockpit crew with no means of controlling the giant jet other than by
adjusting power alternately to the two remaining wing-mounted engines. Without
flaps and spoilers, the only option was to literally “fly” the plane onto the
ground at 250 miles per hour, and pilot Al Haynes and his “front office” crew
did a masterful job of pulling off what they did.
That 184 of the plane’s 296
passengers survived the fiery impact was a miracle which still cannot be fully
explained today. That investigators were
able to put together a jig-saw puzzle of bits and pieces spread across hundreds
of square miles of space and months of time in order to solve a handful of
aviation mysteries is the story behind the story; and the motivation for
today’s column.
The turbofan jet engine gets its
name from the large (71/2 foot diameter) multi-blade fan which sits
at the very front of a modern jet engine pulling in huge amounts of air to both
feed and supplement the thrust of the fuel-driven jet behind it. It was this
fan on the General Electric CF-6-6 engine mounted in the DC-10’s tail section
which exploded on that July day high above Buena Vista County, Iowa, doing
damage to surrounding components – including the illogically-routed hydraulic
lines – before the 400-pound component departed for the earth far below,
subject to the laws of gravity, wind, trajectory and sheer chance.
In summer months, more than 12
million acres of Iowa countryside are clad in a rolling, green and nearly
unbroken canopy of corn. To make searching conditions even worse, those tall
rows of flowering stalks were engulfed in a nearly physical cloud of pollen
dust during the weeks when thousands of citizen volunteers and law enforcement
professionals were tasked with walking a grid pattern through miles of those
breath-constricting rows in search of any piece of wreckage which might lead to
the elusive fan hub in which the ultimate answers were believed to lie. Even a
generous reward system failed to produce results as the trail grew cooler,
while the use of low-flying helicopters only succeeded in angering farmers who
watched their corn fields being blown into patches of mulch.
While the airframe of the DC-10 with
tail number N1819U had seen numerous engine changes in its nearly 20-year
operating life, the particular GE engine in question had seen more than 15,000
cycles (landing/takeoffs) at a time when titanium-rich fan design represented a
relatively-new technology. An entire industry awaited answers as one season
morphed into another.
On the afternoon of October 10th
-- 83 days after UAL 232 and its pieces came to earth -- 58-year-old Janice
Sorenson was driving her harvester down the corn rows near her home just north
of Alta, Iowa when the machine ran up against something that shouldn’t have
been there: the largest part of a disk partially buried in the rich Iowa soil.
Two days later, a neighboring farmer, Harold Halverson found the rest of the
350-pound fan wheel less than two miles away, and the NTSB and a panel of waiting
analysts finally had their “smoking gun.” And a surprised Janice Sorenson would
receive a check for $116,000!
The almost-microscopic flaw which
had bloomed into a crack in the fan wheel’s titanium hub would lead to a whole
new set of testing methods and standards, the DC-10’s hydraulic system would
see major routing changes, and United and other air lines would alter the
frequency and depth of engine testing and replacement protocols.
POST
SCRIPT: As a result of examining the
life changes of Flight 232 survivors and
their rescuers over the years following the incident, we learn that PTSD
with all of its ramifications exists beyond the battlefield and is just as
real.