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Safety Recommendation Details

Safety Recommendation A-12-003
Details
Synopsis: This letter discusses the circumstances of several survivable accidents1 that have occurred in the last 3 years in which overhead bins and passenger service units (PSU)2 on Boeing 737 airplanes became separated from their attachments during the accident sequences, likely increasing the number of reported occupant injuries, particularly injuries to the head and face. In addition to this occupant safety hazard, the negative-g strap3 attachment bracket (used as part of the flight crew five-point restraint assembly) failed in two cases, possibly contributing to back injuries to the flight crewmembers. Findings in these investigations (some of which are ongoing) suggest that current crashworthiness test requirements do not provide an adequate basis on which to evaluate how these items will withstand impact forces during survivable accidents.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: Review the designs of manufacturers other than Boeing for overhead bins and passenger service units (PSU) to identify designs with deficiencies similar to those identified in Boeing’s design, and require those manufacturers, as necessary, to eliminate the potential for PSUs to separate from their attachments during survivable accidents.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Unacceptable Action
Mode: Aviation
Location: Denver, CO, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA09MA021
Accident Reports: Runway Side Excursion During Attempted Takeoff in Strong and Gusty Crosswind Conditions Continental Airlines Flight 1404, Boeing 737-500, NN18611
Report #: AAR-10-04
Accident Date: 12/20/2008
Issue Date: 2/23/2012
Date Closed: 11/20/2014
Addressee(s) and Addressee Status: FAA (Closed - Unacceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 11/20/2014
Response: In your letter, you reiterated that available data indicate (1) that falling PSUs had a negligible effect on evacuation and resulted in no fatalities and (2) that the risk of severe injury from falling PSUs is so low that you would not be justified to require a higher design standard for their attachments in the existing transport airplane fleet. Although falling PSUs may have caused injuries to passengers on Boeing 737s, you state that these injuries were not sufficient to justify your changing the existing regulations or initiating a retroactive action for the transport airplane fleet. We continue to believe that our investigations have identified sufficient evidence of a problem to merit FAA action. Because you plan no further action to address Safety Recommendations A-12-1 or -3, however, these recommendations are classified CLOSED—UNACCEPTABLE ACTION.

From: FAA
To: NTSB
Date: 9/23/2014
Response: -From Michael P. Huerta, Administrator: The data available to the Federal Aviation Administration (FAA), in the form of National Transportation Safety Board {NTSB) accident reports, indicates that the falling PSUs had a negligible effect on evacuation and resulted in no fatalities. The Board provided photographs of the interior of the Continental Airlines flight 1404, Boeing 737-500 accident in Denver, Colorado, on December 20, 2008. The NTSB accident report on this accident, dated July 13, 2010, states: Flight attendant statements indicated that passengers seemed frightened but were responsive to instructions, and the evacuation progressed quickly and smoothly. The flight attendants and deadheading flight crewmembers ensured that all of the passengers were safely evacuated before they exited the airplane themselves ... all airplane occupants had exited and moved away from the airplane before the fire entered the airplane cabin. We have no data from accidents that indicated the PSUs caused any fatalities or impeded egress. The FAA performed a risk assessment of this issue. As the risk severity due to falling PSUs is extremely low, as evidenced by the accidents cited by the Board, the FAA would not be justified in requiring a higher design standard for PSU attachments in the existing transport airplane fleet. We acknowledge there were head and shoulder injuries attributable to the PSUs. These injuries led to Boeing's decision to incorporate a new design into certain Boeing model 737 PSUs, as discussed in our response to A-12-2. However, these injuries do not justify a change to the existing regulations or a retroactive action for the transport airplane fleet in the absence of data indicating the PSUs caused fatalities or impeded egress to an extent that would cause fatalities in a post-crash fire. I believe that the FAA has effectively addressed these recommendations and consider our actions complete.

From: NTSB
To: FAA
Date: 11/6/2012
Response: Thank you for the Federal Aviation Administration’s (FAA) May 18, 2012, letter to the National Transportation Safety Board (NTSB) regarding Safety Recommendations A-12-1 through -6, stated below. We issued these recommendations to the FAA on February 23, 2012, as a result of our investigations of several survivable accidents that have occurred over the past 3 years in which overhead bins and passenger service units (PSU) on Boeing 737 airplanes have separated from their attachments during the accidents and the negative-g strap attachment bracket (used as part of the flight crew five-point restraint assembly) failed. In its letter, the FAA indicated that it had reviewed the related accident data and found no data to indicate that the PSUs or the negative-g strap bracket failure had contributed to serious injury of either passengers or crewmembers. On the basis of its review, the FAA planned not to take the recommended actions; however, the FAA suggested that representatives of both our agencies meet to discuss additional data that could indicate these issues had contributed to passenger or crewmember injury. That meeting took place on August 31, 2012. The FAA’s review of related accident data, described in its May 18, 2012, letter, found that the bins and PSUs that separated from their attachments had been subject to loads that greatly exceeded their certification standards. As stated above, the FAA’s review found no data to indicate that the PSUs attachment failures had contributed to the serious injury of either passengers or crewmembers, and accordingly, the FAA planned not to take the recommended actions. During the August 31, 2012, meeting, we indicated that, although the accident airplanes had experienced fuselage breaks, we did not believe this indicator alone to be an appropriate metric to determine that the accidents were not survivable. FAA staff replied that the FAA’s position was not that the accidents were not survivable, simply that the fuselage breaks made the certification standards for survivability no longer applicable. FAA staff further stated that they could not find data from any of the accidents on which we had based these recommendations to support the need for the actions we recommended. We responded that the accident data that we had described showed the presence of a problem, but the FAA would need to do the appropriate research and analysis to fully understand why the PSUs came down, and what could be done to address the issue. FAA staff again replied that they did not have enough information to justify such an investigation. Although the agency does not plan any further work in response to these recommendations, the FAA’s response to Safety Recommendation A-12-2, discussed above, indicates that the agency is working to understand what caused the PSU attachment failures. That work is in progress, and we believe it will provide the FAA with important information needed before a decision can be made regarding what actions are appropriate in response to Safety Recommendations A-12-1 and 3. In the meantime, until action to implement Safety Recommendation A-12-2 has been completed, enabling the FAA to complete action to address Safety Recommendations A-12-1 and 3 as well, the latter recommendations are classified OPEN—UNACCEPTABLE RESPONSE.

From: NTSB
To: FAA
Date: 6/20/2012
Response: The FAA indicated that it had reviewed the related accident data and found that the bins and PSUs that separated from their attachments had been subject to loads that greatly exceeded their certification standards. The FAA’s review found no data to indicate that the PSUs or the negative-g strap bracket failure had contributed to serious injury of either passengers or crewmembers. On the basis of this review, the FAA does not plan to take the recommended actions; however, the FAA suggested that representatives of both our agencies meet to discuss additional data that could indicate PSUs or overhead bins had contributed to passenger or crewmember injury. We agree that such a meeting would be beneficial, and this meeting is currently being scheduled. Accordingly, the NTSB will classify these recommendations after we have had an opportunity to evaluate the results of the meeting.

From: FAA
To: NTSB
Date: 5/18/2012
Response: -From Michael P. Huerta, Acting Administrator: We reviewed the recommendations and available accident reports. We determined that the aircraft were compliant with applicable regulations regarding the PSU retention and the pilot seat negative-g strap bracket. Load factors experienced during the accidents referenced in the Board's report greatly exceeded certification standards. All the referenced accidents had fuselage breakups, and in these cases we would expect interior items to have some damage as well. Our search found no data to indicate that the PSUs or the negative-g strap bracket failure directly contributed to serious injury of passengers or crew. We welcome the opportunity to meet and discuss additional data that may indicate PSUs or overhead bins contributed to passenger or crew injury. In the absence of such data, we are unable to find the basis for continuing the evaluation. I believe that the FAA has effectively addressed these safety recommendations, and I consider our actions complete.