Portal:TWA Flight 800 investigation/Day2-1
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Portal:TWA Flight 800 investigation
NTSB Board Meeting on TWA 800
August 23, 2000
Jim Hall: Board discussion of the outstanding recommendations that have been made by the NTSB on this accident and then we will move in to a reading of the proposed conclusions of probable cause and recommendations before we vote on the final report.
Before we begin this morning, I would again welcome all of our guests and remind you that, in case of a fire or an emergency, that there are exits on either side of this dais and one in the rear of the room. There will be marshals to direct you out of the building and will also have restrooms and other facilities outside in the lobby area for the convenience of our guests.
I would like to begin this morning by acknowledging the presence of the former vice chairman, Bob Francis, who has been with us through this two-day hearing and who many know as the on-scene board member at the TWA 800 accident. Bob retired from federal service and from the Board at the end of last year. We also have representatives here that, again, I would like to acknowledge from the Transportation Safety Board of Canada and from the French government and we very much appreciate their attendance, as well as we appreciate all of the support and assistance that many other nations identified yesterday have provided to this investigation.
Also, we had present yesterday two individuals that I hold in great esteem that I want to acknowledge: former board member John Lauber who is here with us; John was my mentor when I joined the Board; and our former chairman, Carl Vogt. There are a number of distinguished people in this audience that were here yesterday and here today -- far too many for me to mention but people who are very important, obviously, in the area of aviation safety and we welcome their attention, their presence and their interest in this investigation.
Before I begin, again, let me acknowledge, of course, the presence of the family members of TWA 800 and, again, I will be available all day today if there are issues or areas that you want to speak to the chairman about. I will be available, obviously, during and after this meeting.
Mr. Campbell, I believe we will begin this morning, I guess, with Dr. Loeb and re-introduction of Mr. Swaim or maybe, if everyone can begin yesterday's introduction, then you can just begin with Mr. Swaim. Bob?
Bob Swaim: Thank you, sir. Good morning Mr. Chairman and members of the Board. In this presentation, I would to discuss with you what we learned about the TWA during the TWA Flight 800 investigation about maintenance and aging of aircraft wiring.
While examining wiring in the TWA records, the systems group found: damaged wire insulation, repairs and metal shavings along wire routes, including where the center wing tank fuel gauges would have been for the wires for the gauges, and repetitive repairs to the same re-fueling system, cabin-lighting and gallery squawks.
We also found repairs that were improper. They did not comply with the Boeing standard wiring practices manual. These included: improper hardware and practices used for attaching wires to a strain-release clamp on a left-wing tank compensator; numerous open-ended splices and areas that should have sealed splices, thus exposing the wires to water that could cause short circuits. We found concentrations of splices that could strain wires, an improperly repaired fuel quantity totalizer gauge that could bridge the wires inside an electrical connector, and we found this wire splice from within a left wing fuel tank that we showed at the public hearing.
In an attempt to evaluate whether the condition of the wiring in the accident airplane was typical, the systems group inspected more than 25 other transport category airplanes from various operators, countries and ages. As with the TWA wreckage, we found wiring conditions that did not comply with manufacturer or FAA documents.
For example, the following photograph was taken during the NTSB inspections. The picture shows center wing tank fuel gauge wires, indicated by the yellow arrow, that had sagged onto thicker electrical cables that provided power to the galley. The insulation on these wires were found worn. If left uncorrected, this could have resulted in a hazardous short circuit that could transfer high voltage to fuel gauge wiring that enters fuel tanks.
Even though our focus in this investigation has been on wires that lead into fuel tanks, short circuits can lead to other problems. For example, the pilots of the 767 that these wires were in had to make a precautionary landing after the airplane experienced short circuits in flight that led to system interruptions, misleading cockpit displays, and a small, in-flight fire.
My point is simply that short-circuiting of aircraft wiring can pose many different hazards beyond just the fuel tank ignition hazard that has been highlighted in connection with the investigation.
To prevent damage to adjacent wires, proper wire separation is critical. Our investigation found that there is no uniform standard among manufacturers regarding which wire systems are critical to safety, and the extent to which those wires must be separated from other wiring.
In addition, the Boeing standard wiring practices manual only calls for a quarter-inch of separation between different types of wire bundles. But, as illustrated by the bundle in this photo on the left in the aftermath of this arcing event in the 767, damage to nearby wiring bundles happened an inch-and-a-half away. Further, in some cases the separation of wires is not controlled at all. This photograph was taken over the center wing tank in an older 747 and it shows that the wires are simply laid into a tray. Included in this tray are fuel gauge wires for the center wing tank.
Therefore, because of our concern that there may be insufficient separation of critical wires, the draft report contains a proposed recommendation that the FAA review manufacturers' specifications to identify which systems ARE critical, and then to require revisions that ensure adequate separation exists.
Returning now to our examination of the electrical wiring in other airplanes, I'll continue to list some of the other problems that we found. This photo shows lint bridging circuit breakers in an Airbus Model A-300 that had been operated by an Asian airline, and this is a potential fire hazard. We learned that lint accumulates at different rates in different parts of an airplane but, in general, the newer airplanes have less lint build-up than the older airplanes have.
Another potential hazard that we found were the foreign objects in the electrical system. Also in the circuit breaker panels of the Airbus just shown, we found this metal washer next to the electrical connections. The washer could have either shorted the connections or created a source of ignition for the lint.
The object in the yellow oval is hard to recognize from this angle, but it's a dinner knife from the cabin, above, in the airplane. It apparently slipped down the sidewall. Other foreign objects we found on and around wire bundles included screw drivers, pocket combs, coat hangers and coins.
Here's a photograph of a drill shaving visible on top of a wire bundle and the ends are shown with red arrows. The yellow arrow shows another shaving that has worked its way through the bundle and is just starting to be visible from below. As in the laboratory test that I described yesterday, we found evidence in the airplanes that the drill shavings could, indeed, cut through wire insulation.
The most common sources for drill shavings that we found were structural repairs, and a repair is circled in this photograph of the underside of a 747 cabin floor. Immediately beneath this repair, were more shavings on a wire bundle. We have similar photos from 747's, the A-300 that I showed you, DC9s, and other airplanes.
Drill shavings can be found even in new airplanes. At the bottom of this photograph is a single drill shaving bent around; it's 2 3/4 inches long. This shaving was found on a FQIS wire in a new and undelivered 747-400. As with the lint, we found more shavings in older airplanes than in newer ones.
This photograph of a recently retired 747 with about 100,000 flight hours shows a large number of drill shavings and introduces another commonly found contaminant: fluids. The dark yellow on the surrounding structure is a paraffin-like anti-corrosion spray that had turned dark and sticky on the wires. Referring to the specifications for the manufacture of the wire, we could not find that the wire had been qualified to withstand exposure to this or some of the other chemicals found in the airplane.
This photo is of the same location in another airplane, but here we opened the clamp to examine the wires inside. The yellow arrow shows a hole that had worn through the black woven sleeve that protected one set of wires and through the wire insulation inside. We found exposed copper in other airplanes.
The reason that I am presenting this slide today is to show that there are many wires that simply cannot be visibly inspected, either in the sleeve or in the middle of the larger bundle. Testing has demonstrated that automated test equipment (or ATE) can detect many more discrepancies than visual inspection.
Examining the fuel pump electrical connector from another airplane, the Systems Group found that a rubber grommet exposed to fuel had totally hardened and crumbled out. A 1995 Boeing service letter was later found to contain this photograph and it described how hydraulic fluid in an electrical connector damages the rubber grommet that holds the electrical pins apart. The Boeing caption for the photo that you're looking at stated that, initially, a color change is observed, as we can see here, and that if the contamination is severe enough, all grommet material may be eroded, which we found in the fuel pump.
In this photo are blue stains in the avionics compartment of an airplane that had a lavatory overflow, above, and you can also see from the yellow arrows, points of damage in the wire bundles -- mechanical damage, in this case. Lavatory fluid was found to have caused a major short-circuiting event and a fire in an L1011 last year. But, fortunately, that airplane was on the ground and the passengers could quickly escape.
Another problem we found was corrosion. The wire being pointed to in this photograph has gotten hot enough to darken and have the insulation split away from the connector. Resistance in a wire from corroded connector pins can create heat.
The foam material used in this raceway clamp is clearly degrading. Although it cannot be seen from this angle, the wires are now chafing on hard surfaces. The reason for showing this photo is that it introduces the subject of how materials can degrade over time.
Boeing wrote in a 1995 service letter, the same I referred to previously as the service letter to 747 operators, that the principal causes of wiring degradation were: vibration, maintenance (proper and improper), indirect damage (damage resulting from events not directly related to wiring, such as pneumatic duct ruptures), chemical contamination, and heat.
Therefore, considering what was found in other airplanes and in the Boeing service letter, we concluded that the condition of the wiring in the TWA Flight 800 airplane was not, I repeat not, atypical of an airplane of its age, and that it had been maintained in accordance with prevailing industry practices.
After finding cracked wires and other degraded materials, the NTSB submitted complete wire bundles from two early 1970s 747s and a DC10 to a laboratory at Raytheon Corporation. The bundles were removed from the most protected areas of the fuselage to provide "best-case" examples, rather than looking for problem areas that we knew we could find.
We found wires like this that were cracked through the top layer, and we found wires cracked to the core in airplanes. However, finding cracks is extremely difficult in wiring that is installed, even when the wire can be easily seen.
The Raytheon laboratory confirmed earlier reports that the degradation rate was related to the environment. The same type of wire from different parts of an airplane exhibited different aging rates. With respect to the Poly-X type of wire used in the accident airplane, Raytheon found that the electrical properties were generally met when the wires were not damaged. However, not ONE of the Poly-X samples passed all of the acceptance criteria, and damage was common. A portion of the damage DID penetrate to the core of the wires.
The test results led to finding that the manufacturers and the FAA currently have no standards for providing guidance on allowable levels of degradation, beyond the physical damage criteria shown in the Standard Wiring Practices manuals. They also do not have requirements for periodically re-testing materials, even though we found that aging problems with Poly-X were documented as early as 1975.
Another problem that we discovered was a lack of user-friendly or non-existent maintenance instructions in the Standard Wiring Practices manual. The manual was an 8-inch thick pair of binders that Boeing uses to describe acceptable materials and practices for wiring systems. Although the airlines use the books as part of their approved maintenance documentation, we found that the sheer bulk made it difficult to use anywhere other than at a reference desk. Much of the volume in the manual is simply parts listings, adding numerous pages that would make repair instructions and data difficult to find and extract.
The Standard Wiring Practices Manual can reach extreme levels of detail, such as devoting pages to tying wires into bundles and procedures for specific wires on each airplane model that Boeing has built. One of those procedures describes how to clean specific types of fire detection wires, and another describes connectors. However, the Manual does not contain instructions for how to clean general-purpose wiring that are contaminated with lavatory fluid, metal shavings or lint such as I have shown you here.
As a result of the Safety Board examinations of 1998, an FAA group inspected five further airplanes and the results were similar to what the Systems Group had found. Following these examinations and receipt of a recommendation from the White House Commission on Aviation Safety and Security, the FAA developed the Aging Transport Non-Structural Systems Plan of 1998. The Aging Systems Plan contain the following tasks:
Task 1: Establish an Aging Transport Systems Oversight Committee to coordinate the various aging systems initiatives within the FAA.
Task 2: Conduct an in-depth review of the Aging Transport Fleet to make model-specific recommendations related to the systems.
Task 3: Enhance airplane maintenance to better address aging airplane systems.
Task 4: Add aging systems tasks to the Aging Airplane Research Program.
Task 5: Improve reporting of accident/incident and maintenance actions involving wiring systems components.
Task 6: Evaluate the need for additional maintenance of transport airplane fuel system wires and address any unsafe conditions.
Task 7: Improve wiring installation drawings and instructions for continuing airworthiness.
To assist in developing regulatory changes, the FAA established the Aging Transport Systems Rule-Making Advisory Committee, called ATSRAC, which includes representatives from governments, wire manufacturers, test-equipment providers, industry groups, the manufacturers, and the airlines.
The airlines performed inspections to support ASRAC and the FAA but the inspections were primarily done by airlines on their own airplanes. They recommended some maintenance changes but they have stated that no immediate safety-of-flight issues have been found.
The ATSRAC charter will expire in January, 2001, unless extended, but the FAA's research is expected to continue into future years. The FAA is also doing laboratory examinations on wire system materials that are similar to what we did.
Following an L-1011 in-flight fire in 1991, the Safety Board recommended to the FAA that wiring should be inspected and cleaned. The FAA agreed with this -- with the Board, and then wrote a new handbook for their inspectors and took other actions. As a result, the Safety Board closed Safety Recommendation A-91-70 as "Acceptable Action." However, the inspections conducted by the Systems Group found that the FAA implementation of the earlier recommendation, regarding wire cleanliness, has been ineffective...because the conditions found in 1991 were similar to what was found in 1998.
Staff believes that the Aging Systems Plan of the FAA could address each of the problems that have been shown today. However, staff also has concerns for the implementation of the Aging Systems Plan, due to finding the ineffective implementation of Safety Recommendation A-91-70 and the complexity of the issues that must be addressed in the limited time remaining before the ASRAC expires. Therefore, the proposed recommendation in the draft report states that the FAA should, regardless of the scope of the ATSRAC's eventual recommendations, address all of the issues identified in the Aging Transport Non-Structural Systems Plan, and provide the Safety Board with a progress report.
In summary, Sir, and with respect to TWA, the wiring in the accident airplane was typical for an airplane of its age, and insufficient attention has been paid to the condition of wiring until recently. Mr. Chairman, this concludes my presentation. Thank you, and I'm ready for your questions.
Jim Hall: Thank you Mr. Swaim. I guess the first thing is that your observation that this is typical for its age doesn't give me any "warm and fuzzies" since the plane had 93,000 hours. Could you please elaborate on that?
Bob Swaim: As mentioned, we had more findings in airplanes with increasing time. I'm not, at all, saying, "old is unsafe..."
Jim Hall: Well, we'll get to that in a minute. Page 78 and page 80 -- there seems to be no routine inspections of an aircraft's wiring. Given the difficulties inherent in getting to the wiring, are there any tasks that can be done to test the wiring?
Bob Swaim: There are a limited number of automated-type tests that can be done currently, and newer airplanes built since the mid-80s have built-in test equipment that can be of help, but it can also be a nuisance in giving false findings to mechanics. The big development, the oncoming development that the Aging Systems Plan of the FAA comes to, is that automated test equipment is coming on the scene and it is able to find many, many more discrepancies than can be found by a human and also find them where a human couldn't see in the first place.
Jim Hall: What's the status of that?
Bob Swaim: The FAA, in their research, has been evaluating some of the systems; Eclipse, ECAD, DITMICO, and some of the other companies have been providing equipment for the FAA to test.
Jim Hall: Does the military use any of this equipment at present?
Bob Swaim: The military, actually, is in the same place, almost, as the commercial world. Their problem is the opposite though. In the commercial world, any experienced mechanic can remember bringing up a trailer that was the test equipment and he needed a lot of experience to be able to use it. So the older mechanics have learned to get around it. The military has 19-year old mechanics who don't have the knowledge of the system and the airplane to be able to use it. I've talked at great length with specialists from the Air Force about this.
Jim Hall: Well, I'm aware, of course, I served on the White House Commission with General Loeb, and was extremely concerned about the military wiring and went over in some detail what had been done in the military, and I just want to be sure that we're doing as much on the civilian side as on the military side to address the subject of the wiring issues that are raised in this report. Page 81: you state that, according to the Boeing service letter dated January 25, 1995, that the general rule, wiring that is left undisturbed will have less degradation than wiring that is re-worked. As wiring and components become more brittle with age, this effect becomes more pronounced and I believe you said that all wiring doesn't age at the same rate which doesn't surprise me. Anybody who's been to a high school reunion knows that people age at different rates ... I guess you consider that a significant observation, but the question I have is, Boeing acknowledges that wiring becomes more brittle with age, do they have additional inspections or any replacement plan, or do they just wait `til failure?
Bob Swaim: Wiring has typically been regarded as an "on-condition" item. In other words, it's installed and it remains until there's a reason to remove or replace it. It's periodically part of an area inspection unless it's been a problem in a certain area. They might write a detailed inspection for that particular bundle such as engine pylons. Some airlines will go and actually remove the bundle preemptively from a pylon during a major check, but for the most part of the airplane, that is not the rule.
Jim Hall: Well, what about when you have these alterations? We all know that there's additional avionics, entertainment packages, things being added on the aircraft that obviously require disturbing the existing wiring and adding additional wiring. What is being done in that area? If there's somebody else who needs to respond on that, I'd be delighted ...
Bob Swaim: I asked the back row, I asked for photo 15. Typically, additional systems add wiring to existing wire and we can see the bright white wires in this photograph. There are the wires that were subsequently added. However, there are major modifications, such as Douglas (now Boeing) is doing to modify the DC10s as an MD10, where they are removing wiring for avionics and replacing them.
Jim Hall: Page 85 and page 4 of TWA submission ... this service bulletin, I guess 18194 [STEVE?] that was issued 8/3/95 was not accomplished on the aircraft, even though TWA's submission indicates that all applicable directives have been complied with. Could you please explain that to us?
Bob Swaim: Explain just simply about the service bulletin?
Jim Hall: Why was it not complied with and why was that acceptable?
Bob Swaim: The airline had a certain amount of compliance time and the airplane had not simply reached that time.
Jim Hall: Very well. OK, so it hadn't been done but it wasn't time for it to be done, therefore it was permissible to say that everything had been complied with.
Bernard Loeb: That's correct. At the time the service bulletin was put out, the FAA then was going to mandate it and there was a process that took some time, there, and they were, TWA had time to do that, they were going to do it, but the accident occurred before they were able to get to it and they were within the time limits ...
Jim Hall: Well, you might tell us what's the difference between a service bulletin and a directive? Who makes a decision on those two items?
Bob Swaim: A service bulletin is written by the manufacturer and an airworthiness directive is from the FAA and it's essentially a law that says you will comply with it. In this case, the service bulletin had been written by the manufacturer and the airplane had not gotten to the point that they were replacing it, yet ...
Jim Hall: Was there an AD pending on this?
Bernard Loeb: I think the report reflects that the AD became effective on March 14, 1997. Yes.
Jim Hall: Just an observation, having sat in this seat for six years, we keep seeing service bulletins that come out and then many times the operators wait until it becomes an AD in order to implement it and then you get into this sort of Catch-22 on this particular item, which we have no way of knowing whether it had anything to do with the accident but was an outstanding item that was to be corrected that had not been corrected at the time of the event.
Bernard Loeb: Occasionally, when the ... the service bulletin is recommended by a manufacturer; it does not carry the weight that an FAA requirement does. The AD is a requirement by the FAA. Occasionally, when the carrier knows that the FAA is going to mandate the action, but is uncertain as to whether the action will be mandated specifically the way the service bulletin calls for it, they will wait to see if there's going to be any change because they get concerned at times that they may have to do something slightly different ... they wait until that time comes and it may fit, first of all, into their scheduled maintenance practices better than the time schedule allowed.
Jim Hall: I understand that, I'm just trying to explore whether there should be a way of doing that better and more expeditiously. On page 93 and page 140, lines two to five, points out that there're wires in the accident aircraft that weren't on any Boeing or TWA documents. Now, is that unusual?
Bob Swaim: From our findings, not really. The airplanes go through many checks, modifications, repairs, and, to be able to say that you can find every wire in the airplane just simply from the paperwork, I think would at best be misleading. We also had problems where wires were not identified in the airplane -- they had no markings on them and so you couldn't go to the paperwork and say which wire they were.
Jim Hall: But I assume that it's common sense that the longer something's around, the more possibility it has to be modified, right, in terms of the wiring.
Bob Swaim: Yes, sir.
Jim Hall: I don't ask difficult questions .... (laughter) Dr. Ellingstad, on the subject of aging aircraft and in-flight fires, I think what Mr. Swain was getting ready to say was that he had an old car that still worked and I'm driving a 1992 Dodge Caravan with 196,000 miles. However, I'd like your office of Research and Engineering and your statistical people to review the commercial aviation accidents over the past 20 years to determine if there is any correlation between the age of the aircraft and the accident cause. In particular, as that pertains to catastrophic accidents and in-flight fires. And, I want you to determine, based on this information, whether there is a safety benefit to providing information on the age of the aircraft in commercial service to the American people. And I would appreciate that report by November 15th. I know you don't have anything else to do ...
Dr. Ellingstad: Of, of this year, sir.
Jim Hall: Yes, sir. (laughter) You made a mistake asking that question Mr. Ellingstad; I appreciate you clarifying that. Yes, this year. Member Hammerschmidt?
Mr. Hammerschmidt: Thank you. I have just a couple of questions concerning the issue of foreign material coming in contact with the wiring aboard airplanes and the ability that that could compromise the integrity and safety of that wiring. And Mr. Swaim's very, again, very comprehensive and superb presentation...he made reference to a safety recommendation that the Board issued some nine years ago, identified as safety recommendation A-91-70 and we referenced that in the factual portion of the report on page 325. Let me just read what we have at the bottom of that page, let's see ... on August 14, 1991 the Safety Board issued safety recommendation A-91-70, which recommended that the FAA require "specific quality control and inspection procedures for wire bundle installations on transport category aircraft to verify proper bends, radii, chafe protection and routing practices by aircraft manufacturers during fabrication and by airlines during maintenance operations that expose wire bundles." And, as Mr. Swaim also mentioned, the Safety Board in 1993 classified the FAA's response to our recommendation as "acceptable action." But, then, in the presentation, it was indicated that the FAA's implementation of this recommendation has been ineffective. We come to that conclusion because of the several aircraft inspections that were accomplished subsequent to the TWA Flight 800 accident. And I guess my question is, first, what has led to that FAA action being ineffective? Or, why has the FAA not accomplished what we were looking for? Where has the ball been dropped in the last nine years?
Bob Swaim: Well, the FAA did what they told us they would do. They wrote the operating handbook to their inspectors and they wrote to the airlines. Somewhere between stating what they would do and writing the paperwork, and the airplanes in the field, the implementation was lost. We did not go and look for exactly who was doing what and why they were not cleaning.
Member Hammerschmidt, I just realized something. Now, I personally made the slides that we had on the screen, and I just realized I typo'd that slide; it was the next recommendation A-91-71 which recommended that the FAA notify principal maintenance inspectors and operators, transport category aircraft, of the fire hazard posed by accumulations of lint and other debris on wire bundles. They subsequently issued Bulletin 91-15 and recommended that PMI's and operators comply. So, I did have the wrong number on the slide -- it's the next one -- but the direct answer to your question: we did not specifically go and research that.
John Hammerschmidt: Of course, the two recommendations that you cited are companion recommendations that were issued following a very interesting in-flight occurrence, and I think it might add to the discussion for someone to describe why we issued those safety recommendations -- what the circumstances were of the in-flight fire that led to these recommendations.
Barry Sweedler:: The incident that prompted these two recommendations that we have been discussing took place on March 17, 1991. A Delta Airlines Flight 15, an L-1011 was en route from Frankfurt, Germany to Atlanta, GA at flight level 330 when it experienced a fire below the aft cabin floor in the cabin. That had prompted, after the investigation, prompted these two recommendations that have been cited.
John Hammerschmidt: I remember that when we investigated that in-flight fire -- the cause -- it had the obvious potential for leading to a catastrophe over the ocean on a trans-Atlantic flight. Yet, a passenger reported the fire, which was on the inside of the fuselage wall on the left side as I can recollect, and reported it to flight attendants. The cabin crew, along with coordinating with the flight crew, responded as I can recollect in almost a textbook fashion, and they were able to extinguish the fire. Yet, although we had an occurrence that had a real safety potential associated with it and did not involve real injuries or loss of life, I was hoping that we were making a real impact when we issued those safety recommendations because, obviously what we discovered when we looked underneath the floor of the aircraft, was a surprising accumulation of lint around the wiring in that area, and it seemed to be something of a "wake-up call" to operators of airlines that may not appreciate the safety hazard that that posed. I guess what I'm saying, is in terms of the way the NTSB operates and the way we investigate incidents and non-fatal accidents, that particular investigation, at the time, occurred to be one that a lot of safety potential to it in terms of what could be accomplished, as I say without the loss of life, and in that regard, Mr. Sweedler could you review for us the history of the correspondence we have had with the FAA on those two safety recommendations.
Barry Sweedler:: Certainly. As I mentioned, the recommendation was actually issued, the two recommendations were issued in 1991 and the FAA's first response to us back in 1991 indicated that the FAA had reviewed both the Boeing and McDonnell-Douglas approved quality control and type design date for wire bundle installation as they applied to the proper bend radii, chafe protection and routing practices, and determined that the approved inspection criteria for the wire bundle installations were adequate. The FAA also reviewed, the review also indicated that the inspection acceptance records adequately maintained and documented .... we responded in April of 1992 indicating that we remained concerned that despite the existence of this FAA inspection criteria, that numerous deviations from the design data exist in operation of transport category aircraft, and for that reason, the Safety Board requested that the FAA ensure that effective quality control procedures be carried out also at operator facilities, and we said that we would like a further response from the FAA on that. What they responded in October of 1993, that they were again looking at the practices that I had mentioned...they had indicated that the certification directorate has been asked to evaluate his transport category manufacturer's wire bundle inspection requirements and place special emphasis on the systems during the next audit or evaluation, and they also indicated that to ensure that effective quality control procedures are carried out at the facilities of the individual operators, the FAA issued handbook bulletin 9115 that Mr. Swaim has been discussing, and this handbook bulletin is known as the origin and propagation of inaccessible aircraft fire under in-flight airflow conditions, and the bulletin requests that principle maintenance inspectors review their operators' maintenance programs to ensure that they included inspection of aircraft wiring, especially in inaccessible areas. The bulletin specifically referenced an advisory circular that was entitled, "Acceptable Methods and Techniques and Practices for Aircraft Inspection and Repair" and that particular section concerned wirebend radii. The bulletin has been incorporated into an FAA order in the air-worthiness inspector's handbook. The FAA sent us a copy of this. The staff reviewed what the FAA had done and was proposing, and based on what they had indicated to us, the staff prepared a response back to the FAA, the Board approved this response and sent it to the FAA in February of 1994, closing this recommendation as acceptable action.
John Hammerschmidt: Thank you for that explanation. I remember the details of that investigation and have even used that as an example of how we can make big inroads into aviation safety without injuries and loss of life and when Mr. Swaim had it in his presentation, it just kind of jumped up. The other interesting observation I would have, or at least it was interesting to me, upon reading this report, were the influences of fluids on wire, especially lavatory fluids that we had documented in the report. For instance, we cite a couple of examples in a footnote on page 324 ... we cite an instance that occurred back in 1985 where lavatory fluid was found to have contaminated the wire bundles in the vicinity of improper hot stamp markings resulting in an in-flight fire aboard a 757. We say, additionally, ten years later in 1995, lavatory fluid contaminated electrical components, specifically a connector in the yaw damper circuit resulted in uncommanded roll oscillations in a 737 and I would assume that's what you were referring to in your presentation that, not only do fluids in their contact with wiring present fire problems or potential fire problems, but they also have other consequences as well besides creating the possibility of an in-flight situation or some type of ignition. And, Mr. Swaim, you made reference to a lavatory fluid problem on some wiring on an L-1011 that was on the ground ... what was the result of that occurrence?
Bob Swaim: Well, sir, that was just this last winter and it was an L-1011 that was still on the ground that they were powering up for a departure and they had a leakage problem with toilet fluid that got down into a major wiring bundle in the mid-electronic service center, which is one of the main places that lots of wires and avionics come together in an L-1011. It had a very major arcing event that burned out a large raceway full of wires. The airline went and inspected their other airplanes, I believe they inspected 35 other airplanes, and they found the same problem: toilet fluid stains down in the same area, in the majority of the other airplanes. The one where we had the fire, there was smoke that came up through the sidewall and the passengers fortunately could exit the airplane right there.
John Hammerschmidt: OK. Thank you. One last point: back in the earlier factual portion of this report, we make reference to a maintenance write-up on the accident aircraft which noted, and we have this information on page 94, and it was proceeded by how we describe the flight and cabin crew of the previous flight entered several maintenance write-ups in the logbook which were addressed by TWA maintenance personnel at JFK before TWA Flight 800 departed. They included the drain and galley sea had leaked and the surrounding area of the floor was soaked. Maintenance personnel cleared an obstruction from the drain. Is there any more significance that we should attach to that piece of information?
Bob Swaim: Well, this is one area I showed in a graphic yesterday that we knew we had melted tips of two of the wires and what we did find which was notable because the rest of the bundle or the wires in that raceway had not melted. That is about five feet aft of where this galley leak would have been. If you could have seen some of the 737 toilet fluid leak that when you do have leakage up in the cabin, it has to find a place to get through and down underneath the floorboards even though they're taped at installation, the tape comes loose ...
Jim Hall: Could we possibly put this exhibit up that's in our books that shows aircraft where Galley C is so the audience can understand the significance of Mr. Hammerschmidtshmidt's question? It's a diagram between page 93 and 94 if we have it.
Bob Swaim: Galley C is between the second set of doors, known as L2 and R2, and the location of the wiring that we're talking about is only two or three seat rows behind that on the left side, and pretty much right under the aisle. John, if you could put your pen there, in toward the aisle -- there you go -- that's the location we're talking about, Member Hammerschmidt, and underneath of the pen you can see the stubs that are drawn for the roots of the wings.
John Hammerschmidt: Very good. That's all I have
Bob Swaim: Thank you, sir.
Jim Hall: Member Goglia?
John Goglia: Yes, sir. Just have a few questions. Before we go off that subject, most galleys have what they call a pan underneath them to contain those spills. Now, given it's an old airplane and I don't know the last time it had a heavy maintenance visit, it normally builds a seal and all those spills are kept contained in that area. Not to say that this one did have a good seal in that area or not to say that water didn't possibly affect the outcome that we have here, but normally those areas are sealed to prevent those leaks, which are pretty common, from getting down below. Just thought I would add that. Mr. Swaim, I have a number of questions for you and in your Slide #6, you mentioned wire abrasion and about standards. Are there any standards for the aviation industry for wire abrasion?
Bob Swaim: The advisory circulars have guidance, as you mentioned yourself yesterday, regarding stand-offs and holding wires away from structure and so forth. As far as wire on wire abrasion standards, we know there's a body of data out there -- Boeing has there own standard, Raychem has a test that has become somewhat of a standard, but there is no uniform standard, no.
John Goglia: Who is Raychem?
Bob Swaim: Raychem is a manufacturer of wire including Poly-X.
John Goglia: And, what about the engine manufacturers? Do they use the same wire?
Bob Swaim: They use variations on the same wire, yes, sir. And, as to whether each engine manufacturer has a standard, that I've not researched.
John Goglia: OK. And your Slide #8, you talked about the wire separation and you made a comment that it was not based on safety.
Bob Swaim: I made a comment that was what?
John Goglia: Well, that's what I remember you saying ... it was not based on safety -- the separation standard.
Bob Swaim: The separation is by functional type separation of bundles but in an area like this, the wires are almost randomly laid in the tray. And we found quite a difference between aircraft; we found one airplane where wires were bundled together and another where they were in a different configuration.
John Goglia: OK. You're saying that in manufacturing the airplane that they could be laid in any way -- just laid in the tray.
Bob Swaim: In a tray installation like that, it can happen that they wind up in any configuration. For the most part in the airplane, they are routed through what Boeing, in their case, calls production illustrations. Those say the bundles will be through this series of clamps and shows a series of illustrations through the aircraft. We found that, typically, the wires follow that but not always.
John Goglia: In your Slide #9 you show some lint. I'd just like to comment that that's not uncommon to find in airplanes -- all over the airplanes; I've seen it many, many times. Often, when you open areas that haven't been opened for a long time, you see it. Yesterday we talked about arc-fault circuit breakers a little bit and I'd like you to expand upon the whole concept that about circuit breakers and where we are today with that. Can you give a little explanation for folks in the room to understand the difference between that circuit breaker and a typical one?
Bob Swaim: A typical circuit breaker is basically a little heater that makes a switch move and that is really the long and short of it. To make the heater heat up enough to open the switch and interrupt the circuit, can take anywhere from 60 milliseconds to many, many minutes.
John Goglia: Now, how does it heat?
Bob Swaim: The amount of energy going through a metallic strip inside the circuit breaker makes the strip mechanically bend.
John Goglia: So the electricity passing through this metal strip actually generates the heat.
Bob Swaim: Yes, the resistance to it, yes.
John Goglia: And when that heat builds up to a certain point, it will trip the circuit breaker.
Bob Swaim: Right.
John Goglia: We talked yesterday about some of these ? and spocks that occur in 8 kilovolts which are an example for a lightbulb kilowatts -- a lightbulb growing 10 and a spock having the potential of growing 8,000 watts and that would not generate enough heat to trip the circuit breaker.
Bob Swaim: It's not a matter of the amount of wattage going through it, it's a matter of the time that the circuit breaker has to mechanically respond to it in that case.
Bernard Loeb: That's also a matter of understanding that power doesn't produce heat directly, energy produces heat, heat is a form of energy, and so if you have voltage or wattage, it's a time-dependent issue. You can pour a substantial amount of voltage or power into something for a very, very small period of time and not produce very much heat at all. Or, you can put a smaller amount in it and allow it to exist for a longer period of time, and produce significantly more heat. So, it's a matter of how much voltage you have and, given whatever the conductor is which produces the resistance, it's a matter of the voltage and the time that you have to produce the heat, and the normal circuit breakers are devices that are heat-dependent -- they activate after a certain amount of heat has been able to get into them, so you've got to look at time and voltage.
Bob Swaim: To put a human way you can understand this, if you walk up to a lightbulb, you can touch your finger to it for a second but if you hold your finger on the lightbulb, you'll burn it. Now, in the case of an arc-fault circuit interrupter, or arc-fault circuit breaker, we have those in our houses. However, we don't have them qualified yet to go into the airplanes and that is what is being developed. They will interrupt the circuit as soon as the little microprocessor inside this arc-volt circuit breaker recognizes the electrical characteristics of a short circuit. It says, "I recognize that, I've been programmed to interrupt the circuit," and it does so very quickly.
John Goglia: Thank you. The whole purpose of those questions was to try to explain to some folks that were here yesterday that did not understand what we were talking about, and I think both of you have done a good job of clearing that up for some people.
Bob Swaim: Thank you.
John Goglia: Abrasion and wind and metal shavings -- housekeeping, in general. You made a statement that the military was in about the same place as the industry was. Well, in that area, the industry is behind the military in regards to, as an example, the Navy hit-team. Can you explain that to all of us?
Bob Swaim: Certainly. I believe I was referring to the use of automated test equipment where the military and commercial industry are about the same. In the areas of lint, metal shavings and contamination, the military seems to be cleaner than the commercial fleet for the airplanes that I've looked at, and the military folks we've shared our information with.
As far as the Navy and their hit-team, the Electrical Power Quality Group from Patuxent River with the Navy has established a group that actually, physically goes out and examines airplanes at random. The FAA does not do this -- where they go out and physically inspect airplanes at random to see how they comply with established criteria, specifications in their case, so that's what the hit-team does.
John Goglia: OK, on your Slide #19, you show the overheated pin connector, and on that slide and several others, were not unfamiliar to me. I've seen that before and I've repaired those problems before. However, it's my recollection that I never once filled out a service difficulty report or any other document tracking that. Do you know of any requirements to record those kinds of findings?
Bob Swaim: There is a requirement the FAA has for tracking and for recording maintenance defects. The problem, sir, is that in the electrical world, the FAA has a difficulty in making "data-driven decisions" as they like to say, because there's no way to record this data. The service difficulty reports rely on Air Transport Association (ATO) codes and there currently is not an ATA code for wiring difficulties. So, how can the FAA collect the data if there's no code to collect it against?
John Goglia: Over the last couple of weeks, I've been reviewing the minutes of both the ARAC Committee for Wiring and the Aircraft Wiring and Inert Gas Generator Working Group, AWIGG, and there was a reference in there that the ATA was going to provide those codes, and that was some time ago ... do you know if that's been done?
Bob Swaim: Sir, I believe that came from better than two years ago. We did these inspections in January of 1998; I made my first presentations of our results to the ATA and to the FAA just months later and we heard they would be generating those codes and, to my knowledge, they don't yet exist.
Jim Hall: John, you might explain what the ATA is; I don't think we've gotten into that.
John Goglia: The Air Transport Association of America is a trade association that represents a number of air carriers; it's their technical organization, here in Washington, does develop chapter codes to different areas of the airplane and they have done some pretty good work over the years. I think this may have fallen through the cracks someplace. And I recognize the concern in some of what you said in the document, but it's not spelled out specifically. Without those wiring codes, without a way to report them, report any problems with airplane, that get collected in an orderly manner and fed up through the engineering chain, we would never see any engineering improvements, and, in looking at our findings and looking at the airplane as I have many times up on Long Island, it's clear to me that, I was actually proud of that, because, as I said earlier, I had never filled out any report of the findings. We just fixed what we found and moved on. And, without that closed loop in data that the SDR System and other internal systems are supposed to provide, we would never get to these issues.
Bernard Loeb: And Member Goglia, that's obviously one of the reasons for the recommendation and the way it's framed to the FAA to get at that data documentation is obviously critical to helping to fix this problem.
John Goglia: OK. On Slide 21, Mr. Swaim, you read the Boeing service letter and acknowledged that in the letter Boeing said that condition of wiring is good, yet wires degrade, and I was moved by that, because we know and we've said yesterday, that if you take an airplane like the 747 that has hundred and something of miles of wire, I think someone told me was on the airplane, there's lots of wire on a 747, maybe on average you could say that the airplane is good but there's certainly in certain areas that one needs to pay alot of attention to the wires and I didn't see that, even in the service letter, I didn't see that kind of emphasis put on it and yet we know that problems do exist in certain areas on airplanes.
Standard wiring practices on your slide -- you mention Boeing -- is there any differences between what Boeing's doing and the rest of the industry?
Bob Swaim: The Aging Systems Task Force of the Air Transport Association, the ATA put an ASTF together. The FAA has come with their ATSRAC as I mentioned, and they've acknowledged that there are places where the Standard Wiring Practices Manual could be improved, and made some recommendations. I believe that Boeing is looking at that very seriously right now, the recommendations that have come out of that, and some of our findings.
John Goglia: OK. You talked a little bit about the corrosive sprays. Again, in my past, I have applied those anti-corrosive materials to airplanes and, some of them have been changed because they caused some problems -- the material has changed. Was there an effort in the industry to go back and correct or remove those materials from the airplanes, or was there any action taken to ensure that they didn't cause other problems?
Bob Swaim: That we did not research, sir.
John Goglia: OK. What are your thoughts, Mr. Swaim, on the visual inspections? Very often, in the maintenance programs for wiring, or even for maintenance programs when you enter areas of the airplane that are not normally entered, such as fuel tanks, there'll be a one-liner in the maintenance instructions that will say, "give a general visual inspection to the area." Have you seen problems with that, do we have any thoughts on whether or not it's a good practice, bad practice, do we want to see more detail, etc.?
Bob Swaim: Well, I can relate what we physically found. Trying to leave personal opinions out, I think it's more important to stay with factual findings and we have found some factual findings in areas such as the lint build-ups having collected, as you mentioned yourself. The back of the circuit breaker panels is one area that is a, as you put it, a one-liner inspect for cleanliness and foreign objects in one airplane I looked at, and we found lint.
John Goglia: Now some people might say that it's easy to find problems if you look in enough airplanes and go in and cherry-pick from an airplane faults that are found. How many airplanes did you look at before you got these pictures? Did you have to look at more than a few? Did you have to look at 20?
Bob Swaim: What we put in the docket were the records of 25. We looked at more than that, I just didn't have good records to compile and put into the docket for the other ones. But of the 25, all had some kind of foreign materials except one brand new 737 and that includes the new 747. The difference was that in the new airplanes we had to hunt for findings where in the old airplanes they were readily evident.
John Goglia: Looking at wiring, just at the wire itself now, it's pretty clear that age does matter in the life of wiring, along with the environment ... would you agree with that?
Bob Swaim: It's a difference for each wire in each environment and I don't think we can make a blanket statement.
John Goglia: I wouldn't want to make a blanket statement.
Bob Swaim: OK, thank you. Yes, then.
John Goglia: I know training matters and I don't have that warm, fuzzy feeling the Chairman mentioned a minute ago about how work instructions and our training requirements for the people who are doing this work, and I think that we need to make sure that we help the FAA move along with that issue. You know, instructions are continuing here with airplanes, the FAA has the role of playing that with the carriers and we need to make sure that the FAA plays an active role in that. I've got a number here, but you've already answered some of these questions, so bear with me for a minute. In the course of your work, did you look at any possible replacements for wires? We didn't talk about that at all, but are there other technologies or emerging technologies that could be used in aircraft that could reduce the risk we have from wiring today?
Bob Swaim: Yes, we looked at that some. There are a couple of ways that are actually coming into practice for reducing the risk of wiring problems. I'll just cite two: one is to reduce the number of wires and the other is to come in with a different technology such as the fiber optic, so there are new technologies that are arriving.
John Goglia: Now, in today's modern airplane, we find much greater use of printed circuits than we have ever seen in any airplane flying before. Have we looked at the potential for problems with printed circuits, and sort of looking ahead to see if we're going to get ourselves in trouble in the near future or long-term future with printed circuits?
Bob Swaim: While we looked at that, it's not documented in this report. We've looked at that with the Air Force, because the Air Force has documented some problems. They had a KC-10 and a B1 bomber problem with printed circuit failures where they had electrical arcing jump from one track to another and caused the loss of the B1 and a problem with the KC-10. So, we've looked into it but I can't think of any accidents in the commercial world.
John Goglia: And we've probably had fires but we have no way of collecting that data or accessing it, because it's not collected. Almost all of the inspections I've seen call for a GVI with is a general visual inspection of the area. Would staff favor intrusive inspections to these wire bundle inspections or, to be determined.
Bob Swaim: I think staff would have to get together -- it would be inappropriate for me to give you Bob Swaim's view of the world and I think staff would have to get together and collectively discuss that before we gave an answer.
John Goglia: OK. No further questions, Mr. Chairman.
Jim Hall: Member Black?
George Black: We've been talking here primarily about fuel quantity indicating system wiring, but for instance, that slide you had from London 1998, that was a 767, was it not?
Bob Swaim: Yes, it was; and it was only about six years old.
George Black: And it also was some sort of control cabinet being forced into a slot against the wiring bundle and there was a friction-type thing from that being jammed into place, was there not?
Bob Swaim: It was the sharp corner of a chiller, yes.
George Black: I guess what I'm getting around to is, this is a larger problem than just the fuel quantity indicating system.
Bob Swaim: Yes, sir.
George Black: It has to do with every vital system on the airplane and we've spent all of our time talking because that's what's in this accident, but this applies to all other systems. I seem to recall some problems of a wire chafing on a hydraulic tube in a gear whirl on an airplane, I can't remember what kind it was or what it was that caused fairly severe problems sometimes, just one of our normal incident investigations. So this is a very large problem, it's not just associated with fuel tanks and fuel quantity indicating systems and tank explosions. Since the Chairman asked this question, I think it might need to be emphasized again that your conclusion was sort of benign about the wiring quality on this particular aircraft. You said it was consistent with other aircraft its age but we're certainly not saying that it was acceptable, are we?
Bob Swaim: Absolutely not.
George Black: The level of maintenance on this particular airplane or the fact these splices inside the tank were not meeting wiring standards -- that's certainly not an acceptable situation just because all of them are the same.
Bob Swaim: No, sir. And I had a slide that showed maintenance problems that were found so, no, we found similar problems and other problems in other airplanes.
George Black: And you found them in other models of airplanes -- you had some airbus 300 slides there and other airlines so it's not - we have a problem as a whole with this in aging aircraft.
Bob Swaim: I don't follow your question. continued on part 2
Part 2 | Agenda | Webcast