NASA Gives Details on Critical Parts, Fail-Safe Review Data

NASA today released details on hundreds of parts regarded as vital to the safe operation of the space shuttle, and an engineer described the space agency’s elaborate procedure to “identify where a fail-safe design requirement was not met.”

Marion Merrell of the Johnson Space Center office of Safety, Reliability and Quality Assurance said the review process “started early in the design phase and has been continuously updated, reviewed and reevaluated to date.”

Failure of these critical items would cause “loss of mission, vehicle and crew.”

Among the documents released by the National Aeronautics and Space Administration are several hundred pages dealing with the solid rocket boosters. Seals on the right booster rocket are suspected of failing and contributing to the Jan. 28 destruction of Challenger and the death of its seven crew members.

The material covered potential failures ranging from lightning igniting the booster rocket’s solid fuel while it was on the launch pad--which would cause it to explode--to concerns about the rubber-like O-ring seals in the booster rockets.

Also provided were documents dealing with the external tank that fuels the orbiter’s main engines and with the three main liquid-fuel engines on the spaceplane.

Merrell said that two years ago, program managers for each component of the shuttle were given authority to allow the shuttle to fly with an item that wasn’t fail-safe. Previously, that decision had to be made by a senior official at NASA headquarters in Washington.

“Critical items” is a NASA term for all of the hardware and software components on the space shuttle that must function for safe operation of the craft.

Included on the list are the “criticality 1” items whose failure would cause the loss of the spacecraft and its crew.

A second level of items on the list are called “criticality 1-R,” which are essential systems protected from failure by redundant parts.