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Safety Recommendation Details

Safety Recommendation A-99-022
Details
Synopsis: On 9/8/94, about 1903:23 eastern daylight time, USAir (now US Airways) flight 427, a Boeing 737-3B7 (737-300), N513AU, crashed while maneuvering to land at Pittsburgh Int'l. Airport, Pittsburgh, PA. Flight 427 was operating under the provisions of 14 code of federal regulations (CFR) part 121 as a scheduled domestic passenger flight from Chicago-O'Hare Int'l. Airport, Chicago, Il, to Pittsburgh. The flight departed about 1810, with 2 pilots, 3 flight attendants, and 127 passengers on board. The airplane entered an uncontrolled descent and impacted terrain near Aliquippa, PA. All 132 people on board were killed, and the airplane was destroyed by impact forces and fire. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: Ensure that future transport-category airplanes certificated by the FAA provide a reliably redundant rudder actuation system.
Original recommendation transmittal letter: PDF
Overall Status: Open - Unacceptable Response
Mode: Aviation
Location: ALIQUIPPA, PA, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA94MA076
Accident Reports: Uncontrolled Descent and Collision With Terrain, USAir Flight 427, Boeing 737-300, N513AU
Report #: AAR-99-01
Accident Date: 9/8/1994
Issue Date: 4/16/1999
Date Closed:
Addressee(s) and Addressee Status: FAA (Open - Unacceptable Response)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 1/25/2018
Response: We note that, on May 11, 2010, you received the final recommendations of your Aviation Rulemaking Advisory Committee (ARAC) for revisions to 14 CFR sections 25.671 and 25.1309, and in the 7½ years since then, you have been preparing a notice of proposed rulemaking (NPRM) for these revisions. We further note that your ARAC recommended concurrent issuance of a revision to AC 25.1309-1A, “System Design and Analysis.” The revised AC will provide guidance for showing compliance with the proposed revisions to sections 25.671 and 25.1309, as well as guidance to justify assumptions, data sources, and analytical techniques in safety assessments, and it will advise that extra conservatism be built into the analysis or design when the analytical process is variable or uncertain. The revised AC will also emphasize the importance of including safety critical assumptions in safety assessments to address new technologies that involve intrinsically hazardous equipment. Although you originally intended to publish the NPRM in December 2012, assessing the costs and benefits of the proposed rule has taken considerably longer than you originally expected; as a result, the NPRM and AC revisions have been delayed. We note from your current letter that you are not able to provide an estimated publication date for the NPRM and draft changes to AC 25.1309-1A and that, as an interim measure, you will continue to use issue papers, as you have for many years, to apply the analysis techniques that will be in the NPRM and revised AC to assess failure conditions for all new type certification programs. Although we believe that the NPRM, the resulting final rule, and the revisions to AC 25.1309 1A will satisfy Safety Recommendations A-99-22 and -23, we remain disappointed with the slow pace of progress. Using issue papers to apply the revisions has been an effective interim step, but these recommendations are now 19 years old and there is still no NPRM scheduled for publication to address them, let alone a final rule. Pending publication of the NPRM and a resulting final rule, and of revisions to AC 25.1309 1A that include the recommend requirements, Safety Recommendations A 99 22 and 23 remain classified OPEN--UNACCEPTABLE RESPONSE. Similarly, although the revisions to AC 25.1309-1A will likely satisfy Safety Recommendation A 02 51, it is 15 years old. Pending prompt issuance of the final rule and appropriate revisions being made to the AC, Safety Recommendation A-02-51 remains classified “Open—Unacceptable Response.” In your February 24, 2015, letter about Safety Recommendation A-14-119, you indicated that paragraph 11.h of AC 25.1309 (Arsenal draft) provides guidance to justify assumptions, data sources, and analytical techniques in safety assessments and also advises that extra conservatism be built into the analysis or design when there is variability or uncertainty in the analytical process. You also indicated that the draft AC did not specifically emphasize the importance of including all safety critical assumptions in a safety assessment. At that time, you planned to review the guidance to determine what revisions were necessary to specifically address new technologies that also involve intrinsically hazardous equipment, and you planned to train your engineers and engineering designees about the revised guidance once the revision was finished. Pending release of the revised AC with guidance on including the safety-critical assumptions in safety assessments and on new technologies that also involve intrinsically hazardous equipment, and the provision of adequate training on the revisions for all of your certification engineers and engineering designees, Safety Recommendation A 14 119 remains classified “Open—Acceptable Response.”

From: FAA
To: NTSB
Date: 11/16/2017
Response: -From Michael P. Huerta, Administrator: As noted in our previous letters to the Board, the Federal Aviation Administration (FAA) tasked the Aviation Rulemaking Advisory Committee (ARAC) with recommending refinements to safety rules and guidance concerning these four recommendations. In 2010. the ARAC made recommendations to the FAA to revise Title 14. Code of Federal Regulations§§ 25.671and25.1309, and associated guidance material to further mitigate the risk from latent failures, including control systems jams, as well as the risk of wear-related failures. The ARAC recommendations address the issues raised in all four safety recommendations for future new airplane designs. For existing airplane designs, we have addressed these systems failures through airworthiness directives and continuously monitor this fleet to correct any new issues that arise through our continued operational safety process. For future airplanes and those currently being certified, the FAA applies the analysis of failure conditions to all new type certification programs through issue papers, and will continue this practice on new certification projects, as applicable, until publication of our fin al rule and guidance. We initiated a rulemaking project in 20 11 to incorporate the ARAC recommendations for revising §§ 25.671 and 25.1309, applicable to new airplane designs and significant changes to existing designs. Assessing costs and benefits of the proposed rule took longer than expected and issuance of the Notice of Proposed Rulemaking (NPRM), entitled System Safety Assessments, and associated guidance was delayed. As a result, we cannot provide an estimated publication date for the NPRM and draft changes to Advisory Circular (AC) 25.1309- l A at this time. We continue to work toward issuance of a NPRM to revise §§ 25.67 l and 25.1309. The NPRM is in internal executive level coordination. The ARAC has recommended concurrent issuance of a revision to AC 25.1309-1 A, System Design and Analysis. In addition to providing guidance for showing compliance with the proposed revisions to §§ 25.671 and 25.1309. the revised AC will include guidance to justify assumptions. data sources, and analytical techniques in safety assessments, and advise that extra conservatism be built into the analysis or design when there is variability or uncertainty in the analytical process. The AC will also emphasize including safety-critical assumptions in the safety assessment to address new technologies that involve intrinsically hazardous equipment. The FAA will train our engineers and engineering designees accordingly once there is a final published version of the revised AC. I will keep the Board informed of the FAA's progress on rulemaking and the AC to address these recommendations and provide an update by October 31, 2018.

From: NTSB
To: FAA
Date: 6/12/2015
Response: We note that, on May 11, 2010, you received the final recommendations of your Aviation Rulemaking Advisory Committee for revisions to 14 CFR Sections 25.671 and 25.1309, and since then have been preparing a notice of proposed rulemaking (NPRM) for these revisions. We further note that, although you had intended to publish the NPRM in December 2012, this date has been revised to July 2015 so that you can address concerns about the potential costs and benefits of implementing the recommended requirement. Your letter discussed how the NPRM would address issues related to aging and wear, which are not the subject of either Safety Recommendation A-99-22 or -23; your staff clarified that the NPRM will also address rudder reliability and continued safe flight after the jamming of a flight control. Although we believe that the NPRM and resulting final rule will satisfy Safety Recommendations A-99-22 and -23, we remain disappointed with the slow pace of progress. These recommendations are 16 years old without an NPRM being published to address them, let alone implementation of a final rule. In view of the continuing delay, pending publication of the NPRM and a resulting final rule that includes the recommend requirement, Safety Recommendations A 99-22 and -23 remain classified OPEN—UNACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 3/23/2015
Response: -From Michael P. Huerta, Administrator: As stated in our May 13, 2011, letter, the Federal Aviation Administration (FAA) received the final Aviation Rulemaking Advisory Committee (ARAC) recommendations for changes to 14 CFR §§ 25.671 and 25.1 309. The ARAC determined that aging and wear were covered by § 25.1309, Equipment, systems, and installations, and recommended changes to Advisory Circular (AC) 25.1309-1 A, System Design and Analysis, to clarify how aging and wear should be addressed to meet this regulation. The FAA initiated a Notice of Proposed Rulemaking (NPRM) to address the Board's recommendations. However, due to concerns about the potential costs and benefits of the proposed rule, the NPRM was delayed from its original expected issue date of December 2012. We expect to publish the NPRM for public comment by July 31, 2015, and the updated AC with the subsequent final rule. I will keep the Board informed of the FAA's progress on these safety recommendations and provide an update by October 31, 2015.

From: NTSB
To: FAA
Date: 7/12/2011
Response: The NTSB notes the FAA’s ongoing efforts to address these recommendations. We are aware that, on May 11, 2010, the FAA received the Aviation Rulemaking Advisory Committee’s (ARAC) final recommendations for changes to the CFRs and that the FAA intends, in light of the ARAC’s recommendations, to revise the CFRs. Although we are pleased that the FAA plans to act as recommended, these recommendations are now over 12 years old, and we remain disappointed with the slow pace of progress. Accordingly, pending the completion of these revisions, Safety Recommendations A-99-22 and -23 remain classified OPEN—UNACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 6/13/2011
Response: CC# 201100210: - From J. Randolph Babbitt, Administrator: As noted in our October 3, 2010 response to the Board, we received on May 11, 2010 the final Aviation Rulemaking Advisory Committee (ARAC) recommendations for changes to 14 CFR 25.671 and 25.1309. We also indicated previously that the ARAC recommendations would serve as the basis for a rulemaking action to address these safety recommendations. We are currently developing a notice of proposed rulemaking, which we plan to issue by December 2012. I will keep the board informed of the FAA's progress on these recommendations and provide an updated response by June 30, 2012.

From: NTSB
To: FAA
Date: 2/16/2011
Response: The FAA originally referred these recommendations to two Aviation Rulemaking Advisory Committees (ARAC), one concerned with 14 CFR Section 25.1309, “Equipment, Systems, and Installations,” and the other with 14 CFR Section 25.671, “Control Systems–General.” On April 29, 2003, the FAA published a notice of availability of the ARAC-recommended changes to the airworthiness standards for transport-category airplanes. This notice of availability also indicated that the ARAC-recommended changes could be used in current airplane certification programs. The ARACs also proposed revisions to advisory circular (AC) 25.1309-1A, “System Design and Analysis,” which provides guidance on how to analyze the reliability of aircraft systems. In an October 24, 2008, letter, the FAA stated that it had not yet incorporated the ARACs’ recommendations into the CFRs because it wanted to gather further information and recommendations from the ARACs regarding a number of regulations that involve system safety, to establish standardized criteria and guidance for conducting airplane-level safety assessments of “specific risks.” Although the ARACs’ recommendations had not yet been incorporated into the CFRs, the FAA stated that airplane manufacturers had been applying these standards to the analysis of failure conditions on all new type certificates, and the FAA expected that airplane manufacturers would continue to do so. Therefore, the FAA believed that the intent of Safety Recommendations A-99-22 and -23 had been fully addressed through application of the revised guidance material. The FAA did not believe that the rulemaking that awaited further ARAC recommendations would revise any of the standards and guidance developed by the ARACs in response to these recommendations. On May 12, 2009, the NTSB replied that, although we were disappointed that it had taken 10 years to reach this point, the revisions recommended by the ARACs were responsive to these recommendations, and the application of these standards and practices to new certification programs before the CFRs could be revised constituted a responsive interim action. However, we stated that the revisions would also need to be incorporated into the CFRs before the recommendations could be closed. On May 11, 2010, the FAA received the final ARAC recommendations for changes to the CFRs and has indicated that it intends, in light of the ARAC recommendations, to address these safety recommendations by revising the CFRs. Although the NTSB is pleased that the FAA plans to take the recommended actions, we are very disappointed with the slow pace of progress. Accordingly, pending the completion of these revisions, Safety Recommendations A-99-22 and -23 are classified OPEN -- UNACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 10/3/2010
Response: CC# 201000379: - From J. Randolph Babbitt, Administrator: In previous responses we outlined our plans for changes to 14 CFR 25.671 and 25.1309. We noted that we were awaiting further recommendations from the Aviation Rulemaking Advisory Committee (ARAC). On May 11, 2010, we received the final ARAC recommendations for changes to these and other rules (enclosed). Based on the ARAC recommendations, the FAA intends to address these safety recommendations via rulemaking. I will keep the Board informed of the FAA's progress on these safety recommendations and provide an update by July 2011.

From: NTSB
To: FAA
Date: 5/12/2009
Response: On October 23, 2000, the FAA informed the NTSB that it had referred the issues in these recommendations to two Aviation Rulemaking Advisory Committees (ARACs), one concerned with 14 CFR Section 25.1309, Equipment, Systems, and Installations, and the other with 14 CFR Section 25.671, Control Systems General. On April 25, 2001, the NTSB responded that referral of an issue to an ARAC did not necessarily indicate that the recommended action was being taken and that, without knowing the ARACs’ recommendations or whether the FAA would adopt the ARACs’ recommendations, the NTSB was unable to determine the status of these recommendations. Pending further correspondence and action to address the recommendations, Safety Recommendations A-99-22 and A-99-23 remained classified Open Unacceptable Response. In its current letter, the FAA stated that it had received material from the ARACs regarding revisions to Sections 25.1309 and 25.671 as well as a proposed revision to Advisory Circular (AC) 25.1309-1A, System Design and Analysis. The AC provides guidance on how to analyze the reliability of aircraft systems. On April 29, 2003, the FAA published a notice of availability of the ARAC-recommended changes to the airworthiness standards for transport-category airplanes. This notice of availability indicated that the ARAC-recommended changes could be used on current airplane certification programs. The FAA further indicated that the proposed revision to AC 25.1309-1A has been, and continues to be, widely used in recent certification programs. The AC indicates that aircraft systems are not acceptable if they have a single?point catastrophic failure mode such as a rudder system that is not reliably redundant. The ARAC recommendations for Section 25.671 include changes to the current failure and jamming criteria for flight controls. The FAA stated that it has not yet made the ARACs’ recommendations part of the CFRs because it wants to gather further information and recommendations from the ARACs on a number of regulations that involve system safety, to establish standardized criteria and guidance for conducting airplane-level safety assessments of specific risks. Although the ARAC recommendations in response to these recommendations have not yet been incorporated into the CFRs, the FAA stated that transport airplane manufacturers have applied these standards to the analysis of failure conditions on all new type certificate programs since the Embraer ERJ-170. The FAA expects that airplane manufacturers will continue to apply the standards developed by the ARACs for future airplane certification programs. Therefore, the FAA believes that the intent of Safety Recommendations A-99-22 and -23 have been fully addressed through application of the revised guidance material. The FAA does not believe that the rulemaking that awaits further ARAC recommendations will revise any of the standards and guidance developed by the ARACs in response to these recommendations. Although the NTSB is disappointed that it has taken 10 years to reach this point, the revisions recommended by the ARACs are responsive to these recommendations. Application of these standards and practices to new certification programs before the CFRs can be revised is also responsive. However, these revisions must also be incorporated into the CFRs before the recommendations can be closed. Pending inclusion of the ARAC-recommended changes to 14 CFR Sections 25.1309 and 25.671, Safety Recommendations A-99-22 and -23 are classified OPEN -- ACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 10/24/2008
Response: Letter Mail Controlled 11/6/2008 12:13:58 PM MC# 2080675: - From Robert A. Sturgell, Acting Administrator: On October 23, 2000, the Federal Aviation Administration informed the Board that the FAA was working in cooperation with the Aviation Rulemaking Advisory Committee (ARAC) to revise FAA regulations and guidance material to address the Board’s safety recommendations. The two primary regulations associated with the issues raised by the Board are Q 25.1309, Equipment, systems, and installations, which addresses all systems, and Q 25.67 1 , Control systems - General, which specifically addresses flight control systems. Through the ARAC process, the Systems Design and Analysis Harmonization Working Group, and the Flight Controls Harmonization Working Group, were established to provide recommendations necessary to revise the rules and advisory material for QQ 25.1309 and 25.671 , respectively. The FAA has received the recommendations from these two working groups. These recommendations are available at the following Web address: http://www.faa.gov/regulationsqolicies/rulemaking/committees/arac/issue-areas/ The FAA believes the ARAC recommendations and the FAA’s planned rulemaking and advisory material will address the Board’s recommendations. On April 29,2003, the FAA published a notice of availability of the ARAC-recommended proposed changes to the airworthiness standards for transport category airplanes regarding equipment, systems, and installations, and Advisory Circular (AC) 25.1309-1A (68 FR 22636). This notice of availability indicates that the ARAC-recommended proposed changes may be used on current airplane certification programs through a request for an equivalent level of safety finding. The proposed revised version of AC 25.1309- 1 A, System Design and Analysis, (often referred to as the “Arsenal” version) has been and continues to be widely used by industry during recent certification programs, and specifically prohibits single catastrophic failures. The ARAC recommendations for 3 25.671 include changes to the current failure and jamming criteria for flight controls, as well as a new advisory circular. Although the above ARAC recommendations have not been codified, transport airplanes manufacturers have recognized their value as improved standards. As a result, these standards have been applied to failure conditions on all new type certificate programs since the Embraer ERJ-170, and we expect this will continue to be the case for future programs. With respect to jamming of a flight control, the FAA has been applying a jam criterion of 3 25.671(~)(3t)h at ensures continued safe flight and landing for jam conditions regardless of flight control surface position, unless the jam condition is shown to be extremely improbable. Thus, we believe the safety issues raised by Safety Recommendations A-99-22 and A-99-23 are being addressed through application of revised guidance material. Prior to codifying these ARAC recommendations, we want to gather further ARAC inputs n a number of regulations that involve system safety (such as $3 25.1309,25.671,25.901, 25.933, and 25.981) to help us establish standardized criteria and guidance for conducting airplane-level safety assessment of “specific risks.” However, this rulemaking activity is not expected to change the aforementioned practices related to the subject Safety Recommendations.

From: NTSB
To: FAA
Date: 4/25/2001
Response: The Safety Board notes that referral of an issue to ARAC does not necessarily indicate that the recommended action is being taken. Without knowing ARAC's recommendations or whether the FAA will adopt ARAC's recommendations, the Board is unable to determine the status of the Board's recommendations. Pending receipt of further correspondence, and FAA action to address the recommendations, Safety Recommendations A-99-22 and A-99-23 remain classified OPEN -- UNACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 10/23/2000
Response: Letter Mail Controlled 10/26/2000 4:59:28 PM MC# 2001592 - From Jane F. Garvey, Administrator: The FAA agrees with this recommendation. Existing regulations are intended to ensure reliability and redundancy in all flight control systems. The two primary regulations that apply are 14 CFR 25.1309, which addresses all systems, and 14 CFR 25.671, which specifically addresses flight control systems. The basic objective of these regulations is to ensure that an airplane is capable of continued safe flight and landing following any single failure, and following any combination of failures not shown to be extremely improbable. The FAA is currently working to revise 14 CFR 25.671 and 14 CFR 25.1309 in cooperation with the Aviation Rulemaking Advisory Committee (ARAC). Through this process, the Systems Design and Analysis Harmonization Working Group and the Flight Controls Harmonization Working Group were established to provide rule and advisory material recommendations for 14 CFR 25.1309 and 14 CFR 25.671, respectively. While the basic objective of the requirements will not change, the FAA believes that with improved rules and advisory material, it will be better able to ensure that this objective is met. The Systems Design and Analysis Harmonization Working Group has provided its recommendations to the ARAC, which has forwarded them to the FAA. This includes changes to 14 CFR 25.1309, as well as extensive corresponding advisory material. The FAA is currently developing a notice of proposed rulemaking (NPRM) to amend 14 CFR 25.1309, and associated advisory material. The system safety assessment performed under 14 CFR 25.1309 includes the flight control system and may also be used in demonstrating compliance to 14 CFR 25.671©(1) and ©(2). The flight control system must also meet other requirements like the flight control jams criteria of 14 CFR 25.671©(3). The FAA's activity with regard to these criteria is outlined in the FAA response to A-99-23. I will keep the Board informed of the FAA's progress on this safety recommendation.

From: NTSB
To: FAA
Date: 4/12/2000
Response: In response to each of these three Safety Recommendations (A-99-20, A-99-21, and A- 99-22), the FAA notes that it has convened an engineering test and evaluation board to conduct an in-depth failure analysis of the 737 rudder system. The FAA states that the engineering board will examine all of the issues specified in A-99-21 and, in addition, will also focus on any malfunction that could affect lateral/directional control. The FAA states that the engineering board consists of representatives from the FAA, Boeing, the Safety Board, the National Aeronautics and Space Administration, the Department of Defense, the Air Line Pilots Association, the Air Transport Association of America, and also includes engineers from the Ford Motor Company and from Iluyshin Aviation Complex (a Russian aircraft manufacturing company). The Safety Board supports the establishment of the engineering board and has been impressed with the results of its work to date. The engineering board has developed a substantial amount of additional information about failure modes in the 737 rudder system that were previously identified by the Safety Board, and has identified numerous additional potential failure modes. The engineering board's identification of these additional potential failure modes confirms the validity of the concern, expressed by the Safety Board in its report on the USAir flight 427 accident, that although two identified failure modes associated with rudder reversal had been eliminated by design changes to the 737 rudder system, additional unidentified failure modes might still exist. Therefore, pending receipt of the engineering board's final report, Safety Recommendation A-99-21 is classified "Open Acceptable Response." The engineering board's findings have reinforced the fact that the current 737 rudder system, even with its recent modifications, is not reliably redundant and that design changes are necessary. With regard to Safety Recommendation A-99-20, the FAA states that the engineering board will provide valuable insights, information, and data to determine an appropriate course of action. The Safety Board recognizes that some of the information being developed by the engineering board may be useful in connection with redesigning the 737 rudder system. However, the engineering board was not charged with and has not been, developing a reliably redundant rudder system for the 737 and, therefore, the establishment of the engineering board does not meet the intent of this recommendation. Waiting until the engineering board completes its work and publishes a report will only unnecessarily delay action that has already been demonstrated to be needed and that should have been undertaken as a parallel effort: the provision of a reliably redundant rudder actuation system on 737s. The Safety Board indicated in its report on the USAir flight 427 accident that reliable redundancy could be achieved by developing a multiple-panel rudder surface or providing multiple actuators for a single rudder surface. The Board also suggested two other possible methods by which redundancy might be achieved through use of the standby rudder system. Although the FAA states that it is working closely with Boeing to explore various design options for existing and future 737s, the FAA has not provided any information about progress on the design of a reliably redundant rudder system for the 737. Pending receipt of information about the design options being explored with Boeing and an approximate date when these options could be made available for existing and future 737s, Safety Recommendation A-99-20 is classified "Open Unacceptable Response." Regarding Safety Recommendation A-99-22, the FAA states that it expects that information developed by the engineering board will determine an appropriate course of action for certification of future transport-category airplanes. However, it is unclear how information about the specific failure modes of the rudder system on the 737 (which is the only transport-category airplane with wing-mounted engines that has a single actuator/single rudder surface design) will assist the FAA in ensuring that transport-category airplanes certificated in the future will provide a reliably redundant rudder actuation system, as specified in Safety Recommendation A-99-22. The establishment of the engineering board does not meet the intent of this recommendation. Therefore, because the FAA has not yet taken action to directly address Safety Recommendation A-99-22, pending further appropriate action, it is classified OPEN -- UNACCEPTABLE RESPONSE.

From: FAA
To: NTSB
Date: 6/25/1999
Response: Letter Mail Controlled 6/30/99 3:02:35 PM MC# 990699: - From Jane F. Garvey, Administrator: The FAA has convened an engineering test and evaluation board to conduct a failureanalysis of the Boeing 737 rudder system. It is expected that this group will provide the FAA with valuable insights, information, and data for the Boeing 737 and other rudders of similar design to determine an appropriate course of action. I will keep the Board informed of the FAA's progress on this safety recommendation.