CAPE
CANAVERAL, Fla. - To prevent another catastrophe, NASA
will replace braking mechanisms on all its space shuttles
after discovering some of the gears were installed
backward. Shuttle program manager
Bill Parsons said Monday he had launched an investigation
into why the rudder speed brake gears, all old original
parts in the shuttle tails, were never inspected in more
than two decades of flight. If one of the improperly
installed gears had been in a high-stress position, it
probably would have led to the destruction of the
spacecraft at touchdown, he said.
"Bottom line is, it was not good," Parsons said.
The
rudder speed brake is used to guide and slow the shuttle
as it comes in for a landing. If even one of the four sets
of gears that operate the mechanism jams, then the
spacecraft could not land safely.
As it turns out, the reversed gears found recently in
Discovery were in the least stress-prone position and
never failed. But one of the replacement gears, a spare
set that was also installed backward, would have ended up
in a much more high-stress location in the tail.
All the rudder speed brake gears in NASA's inventory,
dating as far back as the 1970s, are being X-rayed to see
whether they were properly built, and to look for rust and
microcracks, already spotted on some gears.
Parsons
said new or refurbished gears should be installed in time
for shuttle flights to resume next March, after a two-year
grounding following the Columbia tragedy. The extra work
might put NASA a week or two behind, but "I think we'll be
able to make that up," he said.
Discovery will fly first because the work is further
along. Atlantis must be ready to quickly go to the
Discovery crew's rescue at the international space
station, however, if need be during an emergency.
The installation problem surfaced late last year and
prompted NASA to delay the next shuttle flight from fall
2004 to spring 2005.
"Because of the way these gears go together, you can
actually make a mistake and put them in incorrectly, and
there was not a good process back in the timeframe" to
catch mistakes, Parsons said.
He said the maker of the rudder speed brake mechanisms,
Hamilton Sundstrand in Rockford, Ill., now had better
quality control.
Call the Plumber?
At the same time, NASA is inspecting the plumbing in each
of its three remaining shuttles. The hoses in question are
also original parts, and some are starting to leak,
Parsons said.
"As we deal with aging vehicle kind of issues, we will
find other things along these lines as well, I'm sure," he
said.
Parsons said engineers were making good progress on the
inspection booms and wing-repair kits that will be
required on all future shuttle flights.
Columbia was destroyed and its seven astronauts were
killed during re-entry last year because of a hole in the
left wing caused by a piece of insulating foam that broke
free at liftoff. |