The first overhauled Space
Shuttle Main Engine (SSME) high-pressure liquid oxidizer (LOX) turbopump,
which flew on six space shuttle flights during seven years of service, was
delivered to NASA’s primary SSME contractor, Boeing, by Pratt & Whitney (P&W)
Space Propulsion, following a meticulous overhaul and repair process. The
turbopumps are arguably one of the most critical components of the SSME.

Periodic overhauls, in addition to the design and hardware
characteristics, allow turbopumps to operate during 30 or more shuttle
flights. The specified service duration before overhaul is required for P&W’s
LOX turbopump is the equivalent to 11 shuttle missions. This pump, known as
LOX 8015, completed five ground tests in addition to its shuttle flights,
accumulating more than 5,000 seconds of operation.

During the 15-month overhaul and repair process, the turbopump was
completely disassembled and inspected. Where needed, components were
refurbished, upgraded or replaced, but most major parts were re-used,
producing substantial lifecycle-cost benefits to the program.

“This is the only rocket propulsion system in the world that undergoes
true overhaul and repair,” P&W Space Propulsion and Russian Operations
President Larry Knauer said. “Some other systems have recovery and
refurbishment, but that differs significantly from this type of service, since
all of these components have previously flown and returned in working

Three pairs of high-pressure turbopumps (three hydrogen fuel turbopumps
and three liquid oxidizer turbopumps) serve as key components of the upgraded
Block II SSMEs on each of the orbiters. The small but powerful turbopumps
each transmit 76,000 horsepower to deliver liquid hydrogen or 26,800
horsepower to deliver liquid oxygen to the shuttle engines’ main combustion
chambers for ignition. The turbopumps operate in extreme temperatures that
range from minus 420 degrees to 1,400 degrees Fahrenheit.

P&W has supported the Space Shuttle Program since its inception. It has
supplied more than 1,700 booster separation motors since the fleet’s inaugural
voyage in 1981 and began supplying high-pressure liquid oxidizer turbopumps
for the SSME in 1995. In 2001, it supplied the shuttle program with its first
replacement fuel (hydrogen) turbopump, and in April 2002, the Space Shuttle
Atlantis (STS-110) flew with the full P&W power suite (six turbopumps).

P&W’s turbopumps were derived from the company’s extensive experience in
gas turbine engine development and feature fewer welds, a stronger integral
shaft/disk and more robust bearings than their predecessors. When put into
service, they provided NASA with a major improvement in durability,
reliability and operational life. They also reduced maintenance, turnaround
time and operating costs.

P&W Space Propulsion, a leader in liquid, solid, electric and hypersonic
propulsion, has sites located at West Palm Beach, Fla. and San Jose, Calif.
P&W’s Web site address is P&W, a United Technologies company, is a world leader in the design, manufacture and service of
aircraft engines, space propulsion systems and industrial gas turbines.