I am pleased to be here this morning before such a distinguished international group. As a Member of the National Transportation Safety Board, I welcome this opportunity to share my thoughts on fuel system safety and let you know about the work that is being done by the Safety Board, as well as the FAA and the industry.

The NTSB is planning to hold a board meeting later this summer on the TWA 800 accident bringing to an end our investigation. This tragedy, where 230 people lost their lives, has emphasized the need for further understanding and action regarding fuel system safety. Today I'd like to share my views on what we have learned about aircraft fuel systems, the actions that have been taken and where we need to focus in the future.

First, Let me begin by saying that the safety record of fuel systems is good. The fundamental philosophy of precluding ignition sources in the fuel tank has a long history as the basis of fuel system safety. Nonetheless, there have been accidents. This indicates that perhaps we need to turn our focus from trying to eliminate all ignition sources to looking at other ways we can improve fuel system safety. An examination of the history shows that a fuel system related accident on a commercial jet transport has occurred about every 4 years according to the FAA ARAC. Furthermore, accidents have not been limited to one specific model or manufacturer. Where cause has been identified, actions designed to prevent or minimize the possibility of reoccurrence have been taken. Unfortunately, the most recent closed accident remains unexplained- the 737 that exploded on the ground in the Philippines in 1990. The TWA 800 accident is still an open investigation and therefore the cause has yet to be determined . The continuing occurrence of the accidents require that we work harder to further reduce the risk of fuel tank explosions and illustrate that eliminating sources of ignition has not been a successful approach.

In the aftermath of the TWA 800 accident, a tremendous amount of effort has been put forth to identify and address potential problem areas of existing fuel systems. This investigation will forever leave a legacy of three significant changes in aviation. Because of TWA 800, we now look differently at fuel tank protection, how systems age in service, and the protection of vulnerable circuits. The Safety Board, FAA and industry have devoted considerable effort to reevaluating current aircraft fuel systems to confirm their integrity. Chaffed power wires in conduits, malfunctioning fuel pumps, damaged fuel quantity gauging wires, degraded bonding straps are all evidence of the need for improved design and maintenance practices. Airworthiness directives requiring modifications to existing designs are further evidence that existing design practices can be improved.

Finally, the NTSB has long advocated pursuing a meaningful reduction in exposure to flammable vapors in aircraft fuel tanks as a further means of reducing risk of fuel tank explosion. The release of recommendations to this effect in December 1996, four and a half months after the TWA 800 accident, was only the latest in a series of such recommendations. The Safety Board previously recommended in November 1971 that the FAA initiate action to incorporate in its airworthiness requirements, a provision for fuel system fire safety devices which would be effective in the prevention and control of both inflight and postcrash fuel system fires and explosions. Prior to this, the predecessor to the NTSB, recommended in December 1963 that "every effort be expanded to arrive at a practical means by which flammable air/vapor mixtures are eliminated from fuel tanks." In fairness to the industry, a considerable amount of effort has been put forth over the years to evaluate the feasibility of approaches such as nitrogen inerting. To date, the commercial aviation industry has not been able to identify an effective approach that is practical. While the Safety Board recognizes there may be no simple solutions, we will continue to advocate progress in this area.

There are several significant lessons that we have learned from the TWA 800 investigation. Because fuel system accidents continued to occur, we must all work harder to further reduce the risk of fuel tank explosions. It is clear from the investigation and industry efforts that existing fuel system designs and existing fuel system maintenance programs can be improved. We must also continue to address the issue of fuel tank flammability as a means of further reducing the risk of fuel tank explosion.

Now let's turn to the actions that have been taken since the TWA 800 accident. For its part, the Safety Board continues to aggressively pursue the investigation of this accident. In addition, we have released a total of 11 recommendations to the FAA and we will continue to advocate the improvement of fuel system safety. The Safety Board has also conducted a series of fact finding inspections of numerous in-service aircraft, identifying deteriorated conditions in fuel system components. Additionally, the NTSB has sponsored testing and basic research of fuel/air vapor flammability characteristics to help expand the detailed understanding of fuel tank flammability.

Aircraft manufacturers, airlines and industry associations have joined together to voluntarily review the in-service condition of their aircraft fuel systems. Aircraft inspection data are being used to establish the current condition of these systems and to identify any necessary corrective actions. At this time, over one thousand aircraft have been inspected providing valuable data that will support an update to fuel system maintenance programs.

From discussions with Boeing, I am aware that they have a comprehensive program to review their existing fuel system designs across all of their aircraft models. These reviews include their current production and out-of-production aircraft. In addition, Boeing has been very active in evaluating means to reduce fuel tank flammability exposure.

The FAA has been active as well. The recently released notice of proposed rulemaking (NPRM 99-18) for a special FAR (SFAR) to formalize a requirement for all manufacturers to review the original compliance finding of their fuel system certification relative to ignition safety and report their findings to the FAA. This rule would also apply to supplementary type certificate (STC) holders. In addition, all manufacturers would be required to develop enhanced fuel system maintenance programs which the airlines would then be required to implement.

With regards to reducing the flammable vapors in aircraft fuel tanks, the FAA chartered an ARAC task group to evaluate potential ways to reduce fuel tank flammability. This report was published in July 1998. The working group proposed limiting exposure to flammable vapors for newly designed aircraft. The working group did not find a practical way to reduce fuel tank flammability for the current fleet but recommended follow-on activity to look at pack bay cooling evaluations and ground based inerting. The FAA has responded to the group's recommendation by including in the NPRM that defines the SFAR, a proposed rule aimed at reducing fuel tank flammability exposure for new airplane designs. The NTSB will continue to monitor these FAA and industry actions regarding fuel tanks.

The Safety Board recommended in A-98-37 that the FAA examine sulfidation of electrical parts in the fuel tanks. We have continued to work in this area, and are aware that low sulfur fuels are a topic of great interest to the fuel industry. Low sulfur fuels were tried in California and led to deterioration of elastomeric fuel system components, such as o-rings. The Safety Board has been examining the effects that these fuels can have on electrical parts and the results will be contained in our report.

The level of vigilance to correct fuel system related problems has increased. An example of this vigilance is indicated by the more than a hundred service bulletins and AD's that have been issued against various models of all the major jet transport manufacturers.

The Safety Board has long advocated a two-track approach to the fuel tank problem pointed out by the crash of TWA 800. This position is derived in part from lessons learned over the years. Thirty years of accident investigation experience has taught us the value of not relying on a single approach to resolving a serious safety problem.

We applaud the work that has been done to remove all potential ignition sources for fuel tank explosions. The Safety Board believes that additional measures to stabilize fuel tank vapors are necessary and prudent. However, we also recognize the need to proceed carefully in making changes to systems that, on the whole, have performed safely and reliably for extended periods of time. We want to make certain the fixes that are made are the right ones, that they are effective, and that new problems are not introduced.

In closing, I would like to direct your attention to an ARAC summary chart that shows the implementation of proposed changes for vapor protection and ignition prevention has reduced the current fuel tank explosion rate from 1 in 4 years to less than 1 in 32 years. Although these numbers have led to a lot of debate, it is clear that real improvements have been made by anybody's standards.