NASA Investigation Team Reports on Shuttle Engine Damage During June 2000 Test

By Keith Cowing
October 11, 2000
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SSME damage On 16 June 2000, testing of a Space Shuttle Main Engine (SSME) with a high-pressure fuel turbopump configuration at NASA Stennis Space Center had to be cut short. Higher than expected test temperatures caused the SSME to shut itself down 5 seconds into a planned 200-second test.

According to a NASA press release “the SSME being tested was a development unit being used to validate the engine’s capability to operate at higher-than-normal temperature levels. The test used a main combustion chamber smaller than those currently flown on the Shuttle, which increases temperatures in the pumps to test for different temperature limits. “

On 22 June 2000, NASA announced that Robert Sackheim, assistant director and chief engineer for propulsion at NASA Marshall Space Flight Center, would lead an investigative team to find out what happened.

An internal report at NASA dated 10 October 2000, the investigation team reported that there was “minor damage to the fuel preburner and standard throat main combustion chamber” and that “the majority of the damage occurred in the turbine-end. Damage incurred in the turbine downstream of the first
blades resulted from impact. Pump-end hardware was damaged by rub and the loss of roller bearing support.”

The Investigation Board also made the following findings:

Most probable failure scenario and Principle finding

  • During the processing and assembly of SSME 0523, Permacel P-670 tape contamination was
    introduced into the fuel system.

        – Despite normal inspections, the tape went unnoticed during the remainder of the assembly and
    pretest operations.

  • At engine start, the tape was forced downstream and came to rest as debris in the fuel manifold
    of the FPB, causing a localized high mixture ratio in the FPB.

  • The resulting hot streak impinged on the turbine inlet housing struts and first stage vanes.

  • A vane segment burned through and the inner section fell into the first stage blades.

        – This caused rotor imbalance and significant turbine and pump damage.

    Summary of Major Recommendations

  • Verify that all systems are free of foreign object debris prior to hotfire.

  • Limit the opportunity for contamination introduction by minimizing the use of potential
    contaminants and using permanent closures on joints where applicable.

  • Keep joints closed at all times when access is not required to perform work.

  • Implement an improved method of accountability for loose, non-serialized materials used in
    SSME processing.

  • Also, investigate the use of reusable barriers when a contamination barrier is required.”

    Related links

  • 10 October 2000: Summary of Engine Damage, SSME 0523 Test 902-772 Incident Investigation Summary, NASA [300K Adobe Acrobat document]

    Editor’s note: this document contains multiple diagrams and images depicting the damage done to this engine.

  • 10 October 2000: Damage to the HPFTP/AT, Space Shuttle Main Engine
    SSME 0523, 902-772 Incident Investigation
    , NASA [Adobe Acrobat document]

    Editor’s note: this document contains multiple diagrams and images depicting the damage done to the engine’s turbine as well as the investigation team’s findings.

  • 22 June 2000: NASA Forms Team To Review Space Shuttle Main Engine Test Incident, NASA HQ

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