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NASA's Eroding Safety
 

The Columbia Accident Investigation Board will cite serious deficiencies in NASA's overall safety program as a root cause or significant contributing factor to the loss of the space shuttle Columbia and her crew.

 

Investigators believe these deficiencies involve a lack of effectiveness about how NASA has carried out the government's responsibility

for broader oversight, when it transferred more specific vehicle quality control duties to the United Space Alliance (USA) under the Space Flight Operations Contract (SFOC).

 

That will be a significant part of the Board's report," said accident board chairman Adm. (ret) Harold W. Gehman.

NASA will come in for greater criticism than the contractor and NASA's role will likely draw sharp Congressional and Bush administration interest.

The board has conducted about 60 interviews with line technicians in United Space Alliance all the way up through mid-level and senior management at NASA and USA. "And not a single person has said that the quality program is at 100% where it ought to be," said an investigator familiar with those interviews.

Another major problem is that investigators have found "there is no automatic program review" required periodically of NASA's own safety program performance.

"If someone sees something they raise their hand, but there is no overall 'step back to look at performance' to address what we are not doing that we should be doing," an investigator said.

An overemphasis or inappropriate reliance on International Standards Organization ISO 9000 processes is also a problem.

"Simply said, some things that work great for an airline industry that has thousands of flights per week may not be right for a research and development manned space system with only 113 flights under its belt," said board member USAF Brig. Gen. Duane Deal, commander of the 21st Space Wing at Peterson AFB, Col.

He said NASA has "moved toward some things that are in line with ISO 9000 and some operations where you are doing 'sampling' versus a continual look at something that only flies once or twice per year. We are looking very heavily at that, whether that is the right answer for a program like this," Deal said in Houston last week.

Gehman said that rather than safety being stiffened, safety margins on the shuttle have been eroding over the last several years. "We are going to try and restore those safety margins at least back to where we are comfortable with them."

NASA's own internal post-Columbia-accident reviews have also begun to reveal details on past safety-related issues that did not result in incidents, but could have. Those are being uncovered as part of a broad initiative begun in mid-March by former astronaut William Readdy, NASA associate administrator for space flight (AW&ST Mar. 24, p. 36).

In one case, the program failed to replace a Criticality-1-related component that had been showing anomalous behavior. The component in fact did fail during the launch of STS-112 last October, but a redundant system prevented a catastrophe.

The assessment involves a large launch pad cable that carries vital commands for the separation of solid rocket booster hold-down bolts and the retraction of the desk-sized "T-zero umbilicals" that pull out of the orbiter's side at booster ignition.

There are two redundant cables that are both supposed to carry the commands, but during the Oct. 7, 2002, launch of Atlantis on the STS-112 mission, only one of those cables carried the critical command--reducing a Crit-1 function to a single electronics string (AW&ST Nov. 4, 2002, p. 43).

Had the back-up cable failed at booster ignition, the aft sections of both boosters would have ripped off and the T-zero umbilicals would have stayed in the orbiter, resulting in a catastrophic liftoff accident.

The incident was intensively investigated at the time. But what the post-Columbia Crit-1 review has found is that the cable had been

showing anomalous behavior on non-critical low-voltage functions on more than one occasion, sources said. Those analyses, however, failed to adequately address the Crit-1 functions of the higher voltage portions of the cable--which eventually failed during a launch. Whether that process was proper is being re-examined by NASA.

By coincidence, STS-112 was also the same flight where a large section of external tank bipod foam separated and struck the aft skirt of the left booster, but without causing damage. Had managers stopped flights after STS-112 to fix the bipod foam problem, the Columbia accident might have been prevented.

The board last week once again revised the scorecard on bipod foam separation incidents. The new data adds an additional sixth bipod separation event (including Columbia's) and adjusts the total number of shuttle flights where the condition could not be verified photographically to 39 of 113 launches. The board believes that statistically, there were possibly three unseen bipod separation events.

This means that about nine missions in the program had the potential for the same impact suspected of breaching Columbia's wing. The data indicate that, statistically, there was chance for such bipod separations about once every 12-13 missions--about 10% of all shuttle flights.

The board and NASA last week jointly agreed on a working scenario for the Columbia accident that centers the breach in the left wing at reinforced carbon-carbon (RCC) Panels 8-9. But it leaves open for determination key questions such as whether the external tank launch debris impact caused the breach, whether materials deficiencies were involved and whether the breach itself involved separation or fracture of a piece of RCC or its adjoining T-seal.

Even this broad working hypothesis will better focus the complex text and analysis that needs to be completed, Gehman said.

The Board has not yet cited the foam impact as a direct factor in the accident because it still does not have direct physical evidence. "But the board is certainly suspicious that the foam had something to do with this," Gehman said.

That suspicion was again bolstered last week by additional data on Columbia's OEX recorder that showed a pressure spike--like that consistent with a transient shock event--on a pressure sensor mounted behind RCC Panel 9 just a moment after launch cameras captured the debris impact in that area.

"We are very careful that we do not have a scenario-based investigation," Gehman said. He noted the Columbia board findings will probe much deeper than did the presidential commission that investigated Challenger where the failure of a booster O-ring was the irrefutable hardware cause. Initial foam impact tests at the Southwest Research Institute on sections of belly tile last week created little damage to the tile. "If we find areas of safety, or risk assessment, or budgets or oversight or quality control that we think need to be improved in order to make shuttle safer to fly, our report will be rich and complete and cover all these subjects and not be dependent upon whether the foam broke the RCC or not," he said.

To account for the possibility that technical factors other than the debris hit may be involved and to capture the decision-process aspects of the accident, the board will structure its report in four different levels:

* Direct Cause: If, by foam impact tests or other means, the board is able to specifically identify the foam impact or materials or RCC attachment flaws that caused the accident, these will be cited as a direct cause.

* Contributing Factors: "Those would be such things as a weakening of the leading edge. They might be things such as quality control at the shop floor or the construction processes in building the bipod ramp in the first place," Gehman said.

* Root Causes: Gehman said the board is going to reserve this third category for perhaps "aging spacecraft" issues or "cultural kinds of things" like NASA budget impacts, manpower issues, the management system and the attitude of managers in the system.

* Significant Observations: This final category will be reserved for what board members believe are individual significant items they wish to highlight.

 

See Also:
More on the Columbia Investigation