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Safety Recommendation Details

Safety Recommendation A-99-011
Details
Synopsis: ON 2/9/98, N845AA, A BOEING 727-223 (B-727), OPERATING AS AMERICAN AIRLINES FLIGHT 1340, LANDED 180 FEET SHORT OF THE RUNWAY 14R THRESHOLD AT THE CHICAGO O'HARE INT'L. AIRPORT WHILE ATTEMPTING A CATEGORY II INSTRUMENT LANDING SYSTEM APPROACH. OF THE 116 PASSENGERS AND 6 CREWMEMBERS ON BOARD, 22 PASSENGERS AND 1 CREWMEMBER REPORTED MINOR INJURIES. THE AIRPLANE WAS SUBSTANTIALLY DAMAGED.
Recommendation: THE NTSB RECOMMENDS THAT THE FAA: REEXAMINE THE DESIGN OF SEATBELTS INSTALLED ON PASSENGER SEATS ON AIR CARRIER, AIR TAXI, AND COMMERCIAL AIRPLANES TO DETERMINE THE REASON SOME HAVE BECOME UNHOOKED FROM THEIR SEAT ATTACHMENTS DURING TURBULENCE OR A HARD LANDING AND ESTABLISH A SUITABLE MEANS OF ENSURING THAT THE SEATBELTS REMAIN ATTACHED TO THEIR SHACKLES DURING ALL MODES OF FLIGHT.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Alternate Action
Mode: Aviation
Location: CHICAGO, IL, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA98MA023
Accident Reports: Ground Impact of American Airlines 1340
Report #: AAB-01-01
Accident Date: 2/9/1998
Issue Date: 2/19/1999
Date Closed: 4/15/2004
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Alternate Action)
Keyword(s): Weather, Restraint Systems

Safety Recommendation History
From: NTSB
To: FAA
Date: 4/15/2004
Response: At the October 3, 2003, meeting, the FAA noted that the problem this recommendation addresses is related to seat belts that use a D-ring anchor. The FAA stated that this design has not been manufactured since 1992 and that, according to the Air Transportation Association, the seat attrition rate is approximately 8 percent per year. In addition, the FAA estimates that the rate of seat belt failures is 1.9 x 10-10 incidents per seat-hour, which does not support regulatory action to require faster replacement. On December 22, 2003, the FAA issued Special Airworthiness Information Bulletin (SAIB) NM-04-37, which advises operators of transport category aircraft of the problem with D-ring seat belt anchors and urges expedited replacement of these anchors. Because the number of seats affected by this recommendation is continually declining, which reduces the exposure even further than the rate stated above, and because the SAIB urges expedited replacement of D-ring seat belt anchors, the FAA has completed the action recommended with an acceptable alternate approach. Consequently, Safety Recommendation A-99-11 is classified "Closed--Acceptable Alternate Action."

From: NTSB
To: FAA
Date: 8/23/2001
Response: The planned NPRM is responsive to the recommendation. The Safety Board urges the FAA to move expeditiously to implement the final action to replace the D-ring-type seatbelt attachments with the improved design. The FAA anticipates issuing the NPRM by December 31, 2001. Pending issuance of the NPRM by December 31, 2001, and adoption of the requirement, Safety Recommendation A-99-11 remains classified "Open--Acceptable Response."

From: FAA
To: NTSB
Date: 6/12/2001
Response: Letter Mail Controlled 06/26/2001 10:07:00 AM MC# 2010509 The Federal Aviation Administration (FAA) formed an industry team to investigate why the seatbelts become unhooked from their seat attachments during turbulence or hard landings. The team's investigation began with understanding the information gathered from two in-service incidents (Chicago B-727-223 and the Little Rock MD-82). In both incidents, the seatbelt hook end fittings and seatbelt attachment fittings on the seats were not damaged. Since . there was no damage, the industry team rationalized that the spring keeper on the seatbelt end fitting had moved to the open position (see Figure 1) at the same time the opening in the hook end of the seatbelt aligned with the seatbelt attachment fittings on the seat. A load in the direction of the hook end opening subsequently resulted in the seatbelt becoming detached from the seatbelt attachment fittings on the seat. The airplanes involved in the two incidents were configured with Weber Model 4000 seats and a D-ring-type seatbelt attachment (see Figure 2). Many seat manufacturers have used the D-ring-type seatbelt attachment on older seat designs. The team learned that about 10 years ago, most seat manufacturers stopped using the D-ring seatbelt design attachment fittings on new seat designs. Seat manufacturers that are currently manufacturing new seats to designs that are more than 10 years old, however, could still be using the D-ring-type seatbelt attachment. During an investigation into the seatbelt detachment, the team was able to demonstrate a repeatable method for the seatbelt to detach from a D-ring-type seatbelt attachment fitting. When the hook end of the seatbelt is near the seatbelt attachment fitting fastener (see Figure 3) that attaches the fitting to the seat, the hook end of the seatbelt (see Figure 4) can become aligned and contact two points on the attachment fitting. In this configuration, the spring keeper on the belt hook end is in alignment with the upper portion of the D-ring-type attachment fitting. Detachment occurs when an out-of-plane load is applied to the seatbelt end fittings by the seatbelt webbing. As the seatbelt attempts to align the end fitting with the load, the spring keeper is depressed and the seatbelt can become detached from the end fitting. The seat manufacturers have developed new seatbelt attachment fittings that are designed to prevent the seatbelt spring keeper from being loaded by contact with the seatbelt attachment fittings. The team has reviewed and evaluated new seatbelt attachment fittings. One such design is shown in Figure 5. None of the new designs that were evaluated could be manipulated into a configuration in which the seatbelt spring keeper would be positioned so that an applied load would move it into the open position. Therefore, the team concluded that only the D-ring-type seatbelt attachment fittings could be maneuvered into this undesirable configuration. In January 2001, the Society of Automotive Engineers' Seat Committee, along with several seat manufacturers, met to discuss the issue of seatbelt detachment from passenger seats. The seat manufacturers reported that most, if not all, of the seat manufacturers have used D-ring-type seatbelt attachment fittings in passenger seat designs in the past. They also reported that they stopped designing new seats with D-ring-type seatbelt attachment fittings between 10 and 12 years ago. However, they could not identify how many seats with the D-ring-type seatbelt attachment fittings remain in service. Based on the team's findings, the FAA has concluded that only the D-ring-type seatbelt attachment fittings can become unhooked from their seat attachments under certain conditions. Consequently, the FAA plans to issue a notice of proposed rulemaking (NPRM) proposing to require replacement of the D-ring-type seatbelt attachment fittings with seatbelt attachment fittings that reduce the possibility of the seatbelt becoming detached from the seat attachment fitting. It is anticipated that the NPRM will be issued by December 31, 2001. I will provide the Board with a copy of the NPRM as soon as it is issued.

From: NTSB
To: FAA
Date: 11/15/2000
Response: THE SAFETY BOARD IS PLEASED WITH THE FAA'S PROGRESS AND WOULD LIKE FURTHER INFORMATION ABOUT THE FAA'S EVALUATION PROCESS. THE SAFETY BOARD WOULD APPRECIATE LEARNING THE RESULTS OF THESE CONTACTS WITH THE SEAT MANUFACTURERS, AND ACTIONS THE FAA INTENDS TO TAKE TO ENSURE THAT SEAT BELTS THAT MAY BECOME DETACHED IN AN ACCIDENT ARE REPLACED WITH SEATS BELTS THAT ARE DESIGNED TO ELIMINATE THE POSSIBILITY OF THE SEAT BELTS DETACHING. PENDING THE RESULTS OF THE FAA'S CONTACT WITH THE SEAT MANUFACTURERS, THE DETERMINATION OF WHETHER ANY OTHER SEAT DESIGNS HAVE POTENTIAL PROBLEMS, AND THE RECEIPT OF THE REQUESTED INFORMATION, A-99-11 REMAINS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 9/15/2000
Response: Letter Mail Controlled 10/02/2000 3:20:34 PM MC# 2001439 THE FAA HAS TAKEN ACTION ON PREVIOUS RECOMMENDATIONS THAT INVOLVE SEATBELT ATTACHMENT ISSUES. THE WORK DONE BY THE FAA'S FLIGHT STANDARDS SERVICE AND THE CIVIL AEROMEDICAL INSTITUTE AND AIRPLANE-SPECIFIC DATA THAT HAVE BEEN DEVELOPED BY AIRCRAFT CERTIFICATION OFFICES WILL BE EXAMINED AS PART OF THE ACTION PLAN TO ADDRESS THIS RECOMMENDATION. IN RESPONSE TO THIS RECOMMENDATION, THE FAA SENT A REQUEST TO 13 MANUFACTURERS OF AIRPLANES MANUFACTURED UNDER 14 CFR PART 25 AND TO APPROPRIATE REGULATORY AGENCIES FOR INFORMATION REGARDING SEATBELTS DETACHING FROM THEIR SEAT ATTACHMENTS DURING FLIGHT, LANDING, AND ACCIDENTS. TO DATE, THE FAA HAS RECEIVED RESPONSES FROM 11 MANUFACTURERS AND FOUND NO ADDITIONAL REPORTS OF SEATBELT DETACHMENTS. THE FAA ALSO CONDUCTED A DATA SEARCH OF THE NASDAC FOR ANY OTHER REPORTS CONCERNING SEATBELTS BECOMING UNHOOKED FROM THEIR SEAT ATTACHMENTS DURING TURBULENCE OR HARD LANDING AND FOUND NO ADDITIONAL REPORTS CONCERNING THIS ISSUE. THE 11 AIRPLANE MANUFACTURERS EVALUATED THE SEATBELT DETACHMENTS THAT RESULTED IN THE BOARD'S CURRENT AND PREVIOUS RECOMMENDATIONS, AS WELL AS THE SUBSEQUENT ACCIDENT IN 6/1/99, INVOLVING AMERICAN AIRLINES FLIGHT 1420 AT LITTLE ROCK INT'L. AIRPORT. SEVERAL AIRPLANE MANUFACTURERS REPORTED THAT THEY DO NOT USE SEATBELTS THAT HAVE THE SPRING KEEPER DESIGN ELEMENTS, BUT USE SEATBELTS THAT HAVE AN ATTACHMENT FITTING WITH A HOLE AND A BOLT THAT GOES THROUGH THE HOLE TO ATTACH THE ATTACHMENT FITTING TO THE SEAT. THE FAA FORMED AN INDUSTRY TEAM TO INVESTIGATE WHY THE SEATBELTS BECOME UNHOOKED FROM THEIR SEAT ATTACHMENTS DURING TURBULENCE OR HARD LANDING. THE INDUSTRY TEAM HAS DEVELOPED A PROCESS FOR EVALUATING THE DESIGNS OF SEATBELT ATTACHMENT FITTINGS ON SEATS AND HAS REVIEWED SEVERAL SEAT MANUFACTURERS' DESIGNS OF SEATS THAT HAD BEEN SHIPPED TO BOEING FOR DELIVERY ON BOEING AIRPLANES. THE TEAM ALSO VISITED A LOCAL AIRLINE AND REVIEWED OLDER MODEL SEATS. THE TEAM FOUND THAT SOME OF THE OLDER MODEL SEATS HAD SEATBELT ATTACHMENT FITTINGS THAT WERE SIMILAR TO THE SEATBELT ATTACHMENT FITTINGS DOCUMENTED ON THE CHICAGO 727-200 AND LITTLE ROCK MD-82 ACCIDENTS. USING THE PROCESS FOR EVALUATING THE DESIGNS OF THE SEATBELT ATTACHMENT FITTINGS ON SEATS, THE TEAM WAS ABLE TO DETACH THE SEATBELTS FROM THE FITTINGS ON THESE OLDER MODEL SEATS. THE TEAM ALSO USED THE SAME PROCESS TO EVAULATE THE NEW DESIGNS OF THE SEATBELT ATTACHMENT FITTING. THIS EVALUATION DEMONSTRATED THAT THE SEAT INDUSTRY HAS CHANGED THE DESIGN TO ELIMINATE THE POSSIBILITY OF THE SEATBELTS DETACHING FROM THE SEATBELT ATTACHMENT FITTINGS ON THE SEATS. THE FAA WILL CONTACT THE SEAT MANUFACTURERS TO DISCUSS THE SEATBELT DETACHMENT ISSUE AND TO DETERMINE IF ANY OTHER SEAT DESIGNS HAVE SEATBELT ATTACHMENT FITTINGS ON SEATS THAT WOULD RESULT IN SEATBELT DETACHMENT WHEN EVALUATED USING THE PROCESS THAT HAS BEEN DEVELOPED. I WILL KEEP THE BOARD INFORMED OF THE FAA'S PROGRESS ON THIS RECOMMENDATION.

From: NTSB
To: FAA
Date: 2/3/2000
Response: SINCE ISSUING THIS RECOMMENDATION, THE SAFETY BOARD HAS INVESTIGATED ANOTHER ACCIDENT IN WHICH A SEATBELT BECAME UNHOOKED FROM ITS SEAT ATTACHMENT. THE SAFETY BOARD BELIEVES THAT THE INDUSTRY TEAM SHOULD EXAMINE ACCIDENTS AND INCIDENTS BEING INVESTIGATED BY THE BOARD TO GAIN INSIGHT ABOUT WHY SEATBELT DETACHMENTS OCCUR. ADDITIONALLY, THE BOARD BELIEVES THAT MORE SIGNIFICANT INFORMATION WOULD BE GATHERED BY QUERYING AIRPLANE OPERATORS; HOWEVER, THE SAFETY BOARD IS PLEASED THAT THE FAA HAS FORMED A TEAM TO INVESTIGATE WHY SEATBELTS BECOME UNHOOKED AND IS HOPEFUL THAT THE TEAM WILL ESTABLISH A SUITABLE MEANS OF ENSURING THAT SEATBELTS REMAIN ATTACHED TO THEIR SEAT ATTACHMENTS. THE SAFETY BOARD IS WILLING TO OFFER ANY SUPPORT AND INFORMATION IT CAN TO SUPPORT THIS EFFORT. PENDING FURTHER INFORMATION FROM THE FAA, A-99-11 IS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 12/20/1999
Response: Letter Mail Controlled 12/27/1999 8:09:27 AM MC# 991513 THE FAA HAS TAKEN ACTION ON PREVIOUS SAFETY RECOMMENDATIONS THAT INVOLVE SEATBELT ATTACHMENT ISSUES. THE WORK DONE BY THE FAA'S FLIGHT STANDARDS SERVICE AND THE CIVIL AEROMEDICAL INSTITUTE AND AIRPLANE-SPECIFIC DATA THAT HAVE BEEN DEVELOPED BY AIRCRAFT CERTIFICATION OFFICES WILL BE EXAMINED AS PART OF THE ACTION PLAN TO ADDRESS THIS RECOMMENDATION. THE FAA HAS ALSO SENT A REQUEST TO MANUFACTURERS OF AIRPLANES MANUFACTURED UNDER 14 CFR PART 25 AND TO THE APPROPRIATE REGULATORY AGENCIES REQUESTING INFORMATION REGARDING SEATBELTS DETACHING FROM THEIR SEAT ATTACHMENTS DURING FLIGHT, LANDING, AND ACCIDENTS. TO DATE, THE FAA HAS RECEIVED RESPONSES FROM SAAB, EMBRAER, AND THE BOEING COMPANY. OBTAINING RESPONSES FROM ALL OF THE PARTIES IS TAKING LONGER THAN EXPECTED. THE FAA PLANS TO CONTACT THOSE MANUFACTURERS AND REGULATORY AGENCIES THAT HAVE NOT YET RESPONDED AND REQUEST THAT THEY PROVIDE A SCHEDULE FOR COMPLETION OF THIS EFFORT. THE FAA ANTICIPATES COMPLETING WORK ON THIS PROGRAM BY AUGUST 2000. THE FAA HAS FORMED AN INDUSTRY TEAM, INCLUDING REPRESENTATIVES FROM THE BOEING COMPANY AND WEBER AIRCRAFT, TO INVESTIGATE WHY THE SEATBELTS BECOME UNHOOKED FROM THEIR SEAT ATTACHMENTS DURING TURBULENCE OR HARD LANDING. THE TEAM WILL PROPOSE APPROPRIATE CORRECTIVE ACTIONS BASED ON THE RESULTS OF THE INVESTIGATION. THE FAA IS ALSO CONDUCTING A DATA SEARCH OF THE NASDAC FOR ANY OTHER REPORTS CONCERNING SEATBELTS BECOMING UNHOOKED FROM THEIR SEAT ATTACHMENT DURING TURBULENCE OR HARD LANDING.

From: NTSB
To: FAA
Date: 6/2/1999
Response: A-99-11 ASKED THE FAA TO REEXAMINE THE DESIGN OF SEATBELTS INSTALLED ON PASSENGER SEATS ON AIR CARRIER, AIR TAXI, AND COMMERCIAL AIRPLANES TO DETERMINE THE REASON SOME HAVE BECOME UNHOOKED FROM THEIR SEAT ATTACHMENTS DURING TURBULENCE OR A HARD LANDING AND ESTABLISH A SUITABLE MEANS OF ENSURING THAT THE SEATBELTS REMAIN ATTACHED TO THEIR SHACKLES DURING ALL MODES OF FLIGHT. PENDING RECEIPT OF FURTHER INFORMATION FROM THE FAA AS A RESULT OF ITS REVIEW, A-99-11 IS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 4/14/1999
Response: Letter Mail Controlled 5/3/99 4:30:52 PM MC# 990466 THE FAA HAS TAKEN ACTION ON PREVIOUS SAFETY RECOMMENDATIONS THAT INVOLVE SEATBELT ATTACHMENT ISSUES. THE WORK DONE BY THE FAA'S FLIGHT STANDARDS SERVICE AND THE CIVIL AEROMEDICAL INSTITUTE AND AIRPLANE-SPECIFIC DATA THAT HAVE BEEN DEVELOPED BY AIRCRAFT CERTIFICATION OFFICES WILL BE EXAMINED AS PART OF THE ACTION PLAN TO ADDRESS THIS RECOMMENDATION. THE WORK ON THIS PROGRAM SHOULD BE COMPLETED BY NOVEMBER 1999. I WILL INFORM THE BOARD OF THE FAA'S COURSE OF ACTION TO ADDRESS THIS RECOMMENDATION BY SEPTEMBER 1999.