HISTORY

¶Issue

¶Was there sufficient time to correct the problems with the Solid Rocket Motor?

¶Findings

Problems with the joints which connect the Solid Rocket Motor casings were recognized for many years. While attempts were made to correct these problems, the measures taken were insufficient to provide a reliable joint.
The joint seal problem was recognized by engineers in both NASA and Morton Thiokol in sufficient time to have been corrected by redesigning and manufacturing new joints before the accident on January 28, 1986. Meeting flight schedules and cutting cost were given a higher priority than flight safety. Discussion

¶At seven different times in the Shuttle Program, NASA and Thiokol managers made poor technical decisions that ultimately permitted continued flight of an unsafe Solid Rocket Motor design.

NASA's issuing of a performance specification that did not adequately take into account the known weather conditions that occur in Florida during the winter months.
Accepting the new joint design without sufficient certification and testing.
Failure to accept John Miller's recommendations to redesign the clevis joint on ail on-coming hardware at the earliest date.
Establishing a specific value for the upper limit of erosion that could be tolerated in flight on the basis of a "computer program model" instead of recognizing the erosion itself as a failure of the joint.
Proceeding through more than four years of Shuttle flights with continuing joint/seal problems without designing, testing and incorporating a new type of field joint and nozzle joint as well.
NASA's permitting Thiokol to continue making Solid Rocket Motors without conducting full scale tests as had been requested by NASA 14 months previously.
Mr. Mulloy's description of joint failures as being within "their experience base." In other words, if it broke before and the size of the recent break was no bigger than those before, then there was no problem. Even when the erosion surpassed all previous experience, NASA then went on and expanded its "experience base."

¶What follows is a list of events and documents which relate to the cause of the accident. They are included here to demonstrate that there was adequate experience and information available before the accident and that this information should have been sufficient to cause the initiation of corrective action before the launch of Flight 51-L. July IS, 19?3.-NASA issues a Request for Proposal (RFP) for the Space Shuttle Solid Rocket Motor project. Under "Scope of Proposal," the RFP stated in part:

NASA considers that a prime contractor's use of established expertise in the private sector is an essential approach toward the objective of maximum economic effectiveness. Proposals from joint ventures will not be accepted, and the development of new expertise by a prime contractor, either in-house or elsewhere in the private sector, is to be avoided to the extent possible, since the latter course detracts from the stated objective. This RFP is specifically directed toward the design, development, test, production, acceptance, operation, and refurbishment of the Solid Rocket Motor and its ancillary equipment, post-flight analysis, and support functions. It is imperative in all considerations of the proposal and its subsequent implementation, that effort be made to minimize production and operating costs while maintaining reasonable DDT&E costs. The minimization of these costs entails the utilization of design and production approaches that will result in the lowest possible cost per flight consistent with the Space Shuttle Program early year funding constraints and the design, performance and reliability requirements. l a

¶August 27, 1973.-Thiokol, in the Executive Summary to its response to the RFP, addressed NASA concerns regarding SRM reliability (Appendix N, RFP 8-1-4-94-98401). Among other failure modes identified by NASA, Thiokol described the steps it had taken to prevent O-ring seal failure. These included:

DESIGN FEATURES

¶Redundant seals;

¶Protection of mating surfaces;

¶Assure proper environment and capability.

TEST AND CONTROL FEATURES

¶Functional leak check of dual seals prior to test or use;

¶Material migration/compatibility tests to demonstrate suitability. *

¶November 19, 1973.-In its report to NASA Administrator James