Press Release

Shuttle Main Engine Test Investigation Points to Fuel Cell System Contamination

By SpaceRef Editor
October 26, 2000
Filed under

Kirsten Larson

Headquarters, Washington, DC

(Phone: 202/358-0243)

June Malone

Marshall Space Flight Center, Huntsville, AL

(Phone: 256/544-0034)

Lanee Cooksey

Stennis Space Center, MS

(Phone: 228/688-1957)

RELEASE 00-170

A detailed review of a Space Shuttle Main Engine test mishap,
June 16, at NASA’s Stennis Space Center, MS, has revealed that
special tape was left behind inside the engine during processing,
contaminating the system.

“Bob Sackheim and his team did an excellent job of getting to the
root cause of this incident,” said Joseph Rothenberg, NASA
Associate Administrator for Space Flight. “Clearly this incident
was preventable. We must be just as vigilant with our test
hardware as we are with our precious flight engines. Complacency
has no place in space flight.”

Rothenberg appointed Robert Sackheim, Assistant Director for Space
Propulsion at NASA’s Marshall Space Flight Center, Huntsville, AL,
to assess the main engine test mishap.

The investigation team found that nearly 24 square inches of tape,
routinely used as a temporary closure or protective barrier during
main engine processing and assembly, had been inadvertently
dropped into the fuel system. Despite normal processing
inspections, the tape went unnoticed before the engine was test
fired.

The tape came to rest on the fuel and oxygen preburner injectors,
with the majority of the tape in the fuel preburner. The tape
blocked the multiple fuel-inlet holes causing an oxygen-rich mix,
which rapidly increased temperatures beyond the engine’s normal
operating limits and melted some components upstream of the engine
fuel pump.

“The engine controller performed as designed, shutting down the
engine when it sensed a temperature that exceeded the safe limits
set by engineers for this test,” said Sackheim. “The purpose of
these types of ground demonstration tests is to discover any
issues prior to full certification that are related to
manufacturing, assembly, processing, or design so that they will
be prevented from occurring during flight, and that’s what
happened here.”

The test was intended to be a “temperature margin” demonstration
and was part of the developmental phase for a new, more robust
Pratt and Whitney Advanced Technology High Pressure Fuel
Turbopump.

About 5 seconds into a planned 200-second test, higher-than-
expected temperatures caused the shuttle main engine to shut
itself down using its own internal safety mechanisms. The engine
being tested was not a flight configuration, but a development
unit used to validate the engine’s capability to operate at
higher-than-normal temperature levels.

Sackheim’s team found the handling of, accounting for, and
inspecting for loose materials, used to process and rebuild
engines during normal operations, were inadequate. In addition,
his team concluded that the use of tape as a barrier against
contamination provides the opportunity for material to be left in
an engine.

Recommendations in the report to address the incident include:

* Verify all systems are free of foreign objects prior to
hotfire, limit the opportunity for contamination by minimizing the
use of tape and other potential contaminants, use permanent
closures on joints when possible and keep joints closed at all
times when not required to be open for work.

* Implement a better method of dealing with loose, non-
serialized materials to ensure full accounting.

* Investigate the possibility of using reusable barriers for
engine work, which can be controlled and accounted for.

The Space Shuttle Main Engine project and its prime contractor,
the Rocketdyne Propulsion & Power business of The Boeing Company,
are working on a plan to address the report’s recommendations.

In addition, as part of NASA’s emphasis on continued improvement
and safety for the Space Shuttle Program, NASA has initiated an
independent review of the Space Shuttle Main Engine Program and
engine processing at Rocketdyne, as well as operations at NASA’s
Kennedy Space Center, FL.

All Space Shuttle Main Engines have been inspected and cleared for
flight. No evidence of foreign-object damage or tape was found.
The full text of the report can be found at:

ftp://ftp.hq.nasa.gov/pub/pao/reports/2000/ssme_vol1.pdf

SpaceRef staff editor.