Source: https://ntsb.gov/investigations/AccidentReports/_layouts/ntsb.recsearch/Recommendation.aspx?Rec=A-10-065
Timestamp: 2019-06-16 06:49:14
Document Index: 753237433

Matched Legal Cases: ['§ 33', '§ 33', '§ 33', '§ 33', '§ 33', '§ 33']

Safety Recommendation A-10-065
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: During the bird-ingestion rulemaking database (BRDB) working group‘s reevaluation of the current engine bird-ingestion certification regulations, specifically reevaluate the 14 Code of Federal Regulations (CFR) 33.76(d) large flocking bird certification test standards to determine whether they should 1) apply to engines with an inlet area of less than 3,875 square inches and 2) include a requirement for engine core ingestion. If the BRDB working group‘s reevaluation determines that such requirements are needed, incorporate them into 14 CFR 33.76(d) and require that newly certificated engines be designed and tested to these requirements.
Keyword(s): Engine,Rulemaking,Wildlife
Response: You previously told us that a joint FAA and Aerospace Industry Association working group (1) completed its update of the BRDB, (2) reevaluated the large flocking bird certification requirements of section 33.76(d), and (3) found that engines with an inlet area of less than 3,875 square inches are currently operating near the safety objective of the current rule, and that it believed no further revisions are appropriate at this time. We told you that these actions satisfied part (1) of Safety Recommendation A-10-65, and that the ARAC would address part (2) by considering large flocking bird species and whether a new core ingestion requirement is necessary. We note that the ARAC found that (1) the existing medium flocking bird test is at least as stringent for this size engine as the large flocking bird test is for larger engines and (2) a new climb condition medium flocking bird test will further assure the robustness of the engine core. We also note that, based on these findings, the ARAC determined that a new engine core ingestion requirement is not needed. We believe that the ARAC’s consideration of whether a requirement for engine core ingestion is needed satisfies the final part of Safety Recommendation A-10-65, which is classified CLOSED—ACCEPTABLE ACTION.
Response: -From Michael P. Huerta, Administrator: A dedicated FAA and Aerospace Industry Association (AIA) working group updated the BRDB and re-evaluated the large Flocking bird certification requircn1ents of § 33.76(d). As noted in our previous letters, the final report of the AIA working group found that Class D size engines with inlet area less than 3,875 square inches are currently operating near the safety objective of the current rule, even though only 22 percent of engines represented in the updated database are designed to the latest regulations. The AIA found the same for core ingestion events. However, this class of engine is the most statistically significant bird risk category because it accrues the highest number of total flights within the transport category world fleet. The ARAC working group, therefore, considered large flocking bird species and specifically whether a new core ingestion requirement is necessary. The ARAC working group found that the existing medium flocking bird test, including the additional integrity requirement, is at least as stringent for this size engine as the large flocking bird test is for larger engines. In addition, the new climb condition medium flocking bird test proposed in our response to Safety Recommendation A-10-64 will fut1her assure the robustness of the engine core. For these reasons, the working group agrees that no new large nocking bird requirement is needed. I believe that the FAA has effectively addressed Safety Recommendation A- 10-65 and consider our actions complete.
Response: We note that a joint FAA and Aerospace Industry Association working group (1) completed its update of the BRDB, (2) reevaluated the large flocking bird certification requirements of Section 33.76(d), and (3) found that engines with an inlet area of less than 3,875 square inches are currently operating near the safety objective of the current rule and no further revisions are appropriate at this time. This completes part (1) of Safety Recommendation A-10-65. As part of its work described above in response to Safety Recommendation A-10-64, the ARAC will address part (2) by considering large flocking bird species and whether a new core ingestion requirement is necessary. Pending completion of part (2) of Safety Recommendation A-10-65, the recommendation remains classified OPEN—ACCEPTABLE RESPONSE.
Response: -From Michael P. Huerta, Administrator: As noted in our previous response, a dedicated FAA and Aerospace Industry Association (AIA) working group has completed its task to update the BRDB and to reevaluate the large flocking bird certification requirements of§ 33.76(d). The working group detem1ined whether the existing requirements could be relied upon to provide the intended level of safety over time with respect to the large flocking bird threat observed in service. In its final repot1, the AIA working group found that engines with an inlet area of less than 3,875 square inches are currently operating near the safety objective of the current rule. This class of engine statistically has the most significant bird risk because it accrues the highest number of total flights within the transport category world fleet. As part of the ongoing task, the ARAC working group (noted in the response to A-1 0-64) will consider large flocking bird species, and specifically, whether a new core ingestion requirement is necessary. The FAA believes our planned actions are consistent with the general intent of these recommendations and would help keep our engine type certification regulations relevant. I will keep the Board informed of the FAA's progress on these safety recommendations and provide an updated response by December, 2014.
Response: We note that the FAA working group has updated the BRDB and has reevaluated the large flocking bird certification requirements of 14 CFR 33.76(d). The FAA reported that Class D–size engines do not need to be included in the large flocking bird engine test requirements; however, it believes that additional conservatism within the type certification requirements would be wise. To address this concern, the FAA stated that it is considering a rulemaking project in 2012 that would identify a reasonable means to ensure that the world fleet of Class D engines meets the intended safety objective of the current rule. In addition, the FAA reported that a core ingestion test specific to large flocking birds is not necessary, but the FAA plans to strengthen the medium bird core ingestion element, which it believes will result in an increased core ingestion capacity for all bird threats. Pending our review of the FAA’s plan for ensuring that the world fleet of Class D engines meets the intended safety objective of the current rule, Safety Recommendation A-10-65 remains classified OPEN—ACCEPTABLE RESPONSE.
Response: -From Michael P. Huerta, Acting Administrator: A dedicated FAA and AIA working group has completed its task to update the BROB and to reevaluate the large flocking bird certification requirements of § 33 .76(d). The goal of the reevaluation was to determine whether the existing requirements can be relied upon to provide the intended level of safety over time with respect to the large flocking bird threat observed in service. The FAA has reviewed the working group interim report and has the following comments: 1. Class D size engines (inlet area less than 3,875 square inches) are currently operating near the safety objective of the currel1l rule. However, only 22 percent of engines represented in the updated database are designed to the latest regulations, while older engines are designed to less stringent requirements. The FAA expects that overall fleet capability and safety margins will increase markedly in the future as engines designed to the current rule become more prominent in the world fleet. Therefore, there is no current need to include this class engine in the large flocking bird engine test requirement. Nevertheless, this class of engine is the most statistically significant bird risk category because it accrues the highest number of total flights within the transport category world fleet. This is an important consideration as exposure to bird ingestion events primarily occurs during the takeoff and landing phases of flight. Based on these observation s, the FAA believes additional conservatism within the type certification requirements is prudent for these engines to ensure their continued acceptable performance in the future. Therefore, the FAA plans to initiate a rulemaking project in 2012 to identify a reasonable means to ensure that the world fleet of Class D engines meets the intended safety objective of the current rule. 2. Core ingestion of large flocking birds is a relatively small percentage of the overall risk of multi-engine power loss. Because power losses are predominately driven by fan blade fracture and damage, the current engine certification test is considered the best demonstration of overall engine capability against this threat. Also, previous rulemaking efforts revealed that fan ingestions make up the majority of related risk, and that the safety objective of the rule is met without a core ingestion test. Therefore, the FAA does not see the need to add a core ingestion test specific to large flocking birds. However, as discussed above, the FAA plans to initiate a rulemaking project in 2012 to revise and strengthen the medium bird core ingestion element of current § 33.76(c) to make future engine models more tolerant to the general core ingestion threat. Large flocking bird species will be considered in this rulemaking. The strengthened medium bird test will result in increased core ingestion capability for all bird threats. The FAA believes its planned act ions are consistent with the general intent of these recommendations and plans to keep its engine type certification regulations modern and relevant. I will keep the Board informed of the FAA's progress on these safety recommendations and provide an update by July 2013.
Response: From J. Randolph Babbitt, Administrator: A dedicated FAA and AIA working group was formed and is evaluating § 33.76(d). The Pat1 33 BROB was last updated in 2000. The latest update is nearing completion, and has added about 12,000 new bird ingestion records for the 2000-2009 time period. A preliminary review of the data shows that the in-service, multi-engine ingestion rates for this time period are not significantly greater than the rates from the 2000 data, and are close to the predicted rates for 2010. The current regulation is based on the predicted rates for 2010. Also, the new data shows that engine power loss rates for a given ingestion have generally improved over this time period. This is likely because the world-wide fleet now includes a greater number of newer, more capable engine models. These preliminary observations tell us that the overall large flocking bird threat has not significantly worsened in this time period. However, much work remains to determine whether the current regulation will continue to meet our overall safety objective or if new rulemaking, policy, or method of compliance guidance is required. I will keep the Board informed of the FAA's progress on these safety recommendations and provide an update by August 2012.
Response: CC# 201000368: - From J. Randolph Babbitt, Administrator: The FAA/ AIA working group referenced in our response to recommendation A-10-64 will also re-evaluate § 33.76(d). New rulemaking, policy, or method of compliance guidance could result from this effort.