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Safety Recommendation Details

Safety Recommendation A-00-107
Details
Synopsis: On 7/17/96, about 2031 eastern daylight time, Trans World Airlines, Inc. (TWA) Flight 800, a Boeing 747-131, N93119, crashed into the Atlantic Ocean near East Moriches, New York. TWA Flight 800 was operating under the provisions of 14 Code of Federal Regulations (CFR) Part 121 as a scheduled international passenger flight from John F. Kennedy International Airport (JFK), New York, NY, to Charles de Gaulle International Airport, Paris, France. The flight departed JFK about 2019, with 2 pilots, 2 flight engineers, 14 flight attendants, and 212 passengers on board. All 230 people on board were killed, and the airplane was destroyed. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: Require the development and implementation of corrective actions to eliminate the ignition risk posed by silver-sulfide deposits on fuel quantity indication system components inside fuel tanks. (Supersedes Safety Recommendation A-98-037)
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: EAST MORICHES, NY, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA96MA070
Accident Reports: In-flight Breakup Over the Atlantic Ocean Trans World Airlines Flight 800, Boeing 747-141, N93119
Report #: AAR-00-03
Accident Date: 7/17/1996
Issue Date: 9/19/2000
Date Closed: 1/11/2011
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s): Fire,Wiring

Safety Recommendation History
From: NTSB
To: FAA
Date: 1/11/2011
Response: The FAA completed its research program investigating silver sulfide deposits on FQIS components and, in October 2003, published its findings in a report titled Silver-Sulfur Deposits on Fuel Quantity Indication System and Attendant Wiring. The research project successfully grew deposits and studied their properties. On September 19, 2008, the FAA issued advisory circular (AC) 25.981-1C, “Fuel Tank Ignition Source Prevention Guidelines,” which provides information on the possible degradation of airplane fuel tank system safety features caused by conductive or semi-conductive corrosion silver-sulfide deposits at electrical connectors inside fuel tanks. The AC also contains information on the results of the research conducted and advisory material on the use of silver in fuel tanks. The actions described above in response to Safety Recommendations A-98-38 and -39 require that the information on silver-sulfide deposits in AC 25.981-1C be included in actions to eliminate ignition risks in fuel tanks. Consequently, Safety Recommendation A-00-107 is classified CLOSED -- ACCEPTABLE ACTION.

From: FAA
To: NTSB
Date: 7/8/2010
Response: MC# 2100256 - From J. Randolph Babbitt, Administrator: The FAA research program established in response to safety recommendation A-98-037 (superseded by this recommendation) is complete. The FAA published its findings in DOT/FAA/AR-03/61, "Silver-Sulfur Deposits on Fuel Quantity Indication System and Attendant Wiring," dated October 2003 (see enclosure 7). The researchers were able to grow deposits and study the samples' properties. On April 18, 2001, the FAA issued Advisory Circular (AC), 25.981-1 B, "Fuel Tank Ignition Source Prevention Guidelines," which provided information on the possible degradation of airplane fuel tank system safety features caused by conductive or semi-conductive corrosion silver-sulfide deposits at electrical connectors inside fuel tanks. Based on the results of research conducted, additional advisory material on the use of silver in fuel tanks was included in revision C of this AC, issued on September 19, 2008 (see enclosure 4). Silver sulfide deposits resulting in arc gaps inside fuel tanks are one of a number of failure modes within the fuel tank system. Arc gaps can become an ignition source if power levels above intrinsically safe levels are introduced into the fuel tanks due to failures outside the tank, such as a "hot short" or induced currents from adjacent wires. The FAA required FQIS protection on certain Boeing Model 73 7 and 747 series airplanes by AD requiring separation of the FQIS wiring from other airplane wiring. I believe that the FAA has satisfactorily responded to this safety recommendation, and I look forward to your response.

From: NTSB
To: FAA
Date: 5/17/2002
Response: The Board believes that this research program has produced useful information and looks forward to the completion of the investigation of sulfide deposits and intrinsically safe electrical energy levels. The Safety Board points out that it has already cited examples of sulfide accumulations on in-service aircraft and notes that the laboratory-created samples have been used to create ignition. Pending the development and implementation of methods to eliminate the ignition risk posed by sulfide deposits on FQIS components inside fuel tanks, Safety Recommendation A-00-107 remains classified OPEN -- ACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 5/24/2001
Response: Letter Mail Controlled 05/31/2001 9:08:49 PM MC# 2010450: - From Jane F. Garvey, Administrator: This safety recommendation superseded Safety Recommendation A-98-37, which recommended that the FAA require research into copper-sulfide deposits on FQIS parts in fuel tanks to determine the levels of deposits that may be hazardous, how to inspect and clean the deposits, and when to replace the components. The actions initiated to respond to Safety Recommendation A-98-37 are the same actions that will address Safety Recommendation A-00-107. As stated in the FAA's letter dated May 17, 2000, in response to Safety Recommendation A-98-37, the FAA's research program is continuing to make progress in understanding the deposits and evaluating potential hazards that may be created by the copper-sulfide or silver-sulfide deposits. The researchers have grown deposits in a laboratory and have studied the properties of those laboratory samples. However, the team has not found any indication of significant levels of deposits occurring in in-service airplanes in order to compare them to the laboratory-grown deposits. The research program was extended from the original 12-month program to include a Phase 2 program so the team can complete its evaluation. Phase 2 of the research program will include testing of laboratory-grown deposits with low (intrinsically safe) electrical energy levels that are permitted in fuel tank fuel quantity gauging wires. A Phase 2 status review meeting was held on February 1, 2001, and a representative of the Board attended the meeting. The results of the initial testing conducted as part of the Phase 2 program were reviewed during the meeting. The testing using the intrinsically safe electrical energy levels had not been completed at that time, and it was agreed that those tests should be completed as soon as possible. The status of other Phase 2 research activities was also reviewed and future activities discussed. If the research shows that sulfide deposits create a hazard at intrinsically safe electrical energy levels, the FAA will require appropriate corrective action to eliminate the hazards. I will keep the Board informed of the FAA's progress on this safety recommendation.

From: NTSB
To: FAA
Date: 12/5/2000
Response: FAA and Safety Board staff met on 10/17/00, to discuss these recommendations. The meeting initiated a dialogue that will lead to mutually agreeable actions for each of these recommendations. The FAA anticipates providing the Board with a complete response to these recommendations by 1/31/01. Pending submission of that complete response, A-00-105 through -108 are classified OPEN – ACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 10/12/2000
Response: Letter Mail Controlled 10/16/2000 3:58:40 PM MC# 2001542 - From Jane F. Garvey, Administrator: Your staff has agreed to meet with FAA technical specialists on 10/17/00, to discuss these recommendations. This meeting will offer an opportunity to begin a dialogue between our agencies that can lead to mutually agreeable actions for each of these recommendations. After this meeting, the FAA will have a better understanding of the intent of these recommendations and be in a better position to provide detailed response to these recommendations. We anticipate providing the Board with a complete response to these recommendations by 1/31/01.