Safety Recommendation A-10-064

We note that, on April 4, 2023, you published the final rule, “Medium Flocking Bird Test at Climb Condition,” which revised Title 14 CFR 33.76 to include an additional test element for certifying turbofan engines that will ensure these engines can ingest the largest medium flocking bird required for bird ingestion testing into the engine core at climb or approach conditions. We continue to believe that this additional test element is an acceptable alternate solution to using the lowest expected fan speed, as recommended. Consequently, Safety Recommendation A-10-64 is classified CLOSED--ACCEPTABLE ALTERNATE ACTION.

-From Kathryn Thomson, Deputy Administrator: The Federal Aviation Administration (FAA) published the Medium Flocking Bird Test at Climb Condition Final Rule (88 FR 19801) on April 4, 2023, which is effective on June 5, 2023. This final rule revises §?33.76 to create an additional bird ingestion test for turbofan engines. This new test ensures that engines can ingest the largest medium flocking bird required for bird ingestion testing into the engine core?at climb or approach conditions.

To obtain certification of a turbofan engine, a manufacturer must show the engine core can continue to operate after ingesting such a bird while operating at a lower fan speed associated with climb or approach.

I believe the FAA has effectively addressed Safety Recommendation A-10-64 and consider our actions complete.

We note that the final rule associated with the July 6, 2018, notice of proposed rulemaking (NPRM), “Medium Flocking Bird Test at Climb Condition,” has been delayed again. We continue to believe a final rule that is consistent with the NPRM would be an acceptable alternate solution to this recommendation; however, the continued delays associated with this rulemaking are unacceptable. Pending the publication of the final rule with the revisions to 14 CFR 33.76(c) proposed in the NPRM, Safety Recommendation A-10-64 is classified OPEN--UNACCEPTABLE RESPONSE.

-From Billy Nolen, Acting Administrator, Federal Aviation Administration: As stated in our previous letters, the Federal Aviation Administration (FAA) published the “Medium Flocking Bird Test at Climb Condition” notice of proposed rulemaking (83 FR 31479) on July 6, 2018, and informed the Board that other rulemaking priorities delayed the final rule.

Publication of the final rule continues to be delayed due to other rulemaking priorities. The draft final rule is currently in executive-level review, and we anticipate publishing the final rule by September 30, 2022.

I will keep the Board informed of the FAA’s progress on Safety Recommendation A-10-64 and anticipate providing an update following the publication of the final rule, but no later than August 31, 2023.

-From Steve Dickson, Administrator: As previously stated, the Federal Aviation Administration (FAA) published the Medium Flocking Bird Test at Climb Condition Notice of Proposed Rulemaking (83 FR 31479) on July 6, 2018, and informed the Board that we expected to publish the final rule by summer 2021. However, the final rule is further delayed due to other rulemaking priorities and is anticipated to be published by April 30, 2022.

I will keep the Board informed of the FAA’s progress on Safety Recommendation A-10-64 and anticipate providing an update by July 31, 2022.

We note that, because of other, higher priority rulemaking projects, the final rule associated with the July 6, 2018, notice of proposed rulemaking (NPRM), “Medium Flocking Bird Test at Climb Condition,” has been delayed until later this year. Pending the published final rule with the revisions to 14 CFR 33.76(c) proposed in the NPRM, Safety Recommendation A-10-64 remains classified OPEN-- ACCEPTABLE ALTERNATE RESPONSE.

-From Steve Dickson, Administrator: On July 6, 2018, the Federal Aviation Administration (FAA) published the Medium Flocking Bird Test at Climb Condition Notice of Proposed Rulemaking to revise § 33.76 to include an additional certification test, run at a higher airspeed and lower fan speed than the current core ingestion test (83 FR 31479). We expected to publish the final rule by summer 2020, but other rulemaking priorities caused unexpected delays in the rulemaking process. We are scheduled to issue the final rule for publication in summer 2021.

I will keep the Board informed of the FAA’s progress on this recommendation and anticipate providing an update by December 31, 2021.

We are aware that, on July 6, 2018, you published a notice of proposed rulemaking (NPRM), “Medium Flocking Bird Test at Climb Condition,” which proposed, for turbofan engines, an additional bird ingestion test run at a higher airspeed and lower fan speed than the current medium bird core ingestion test. We are also aware that your Aviation Rulemaking Advisory Committee working group recommended the test that you included in the NPRM. In our August 24, 2018, comments responding to the NPRM, we said the proposed rule, when implemented, would be an acceptable alternate solution to Safety Recommendation A-10-64.

We note that a final rule has been drafted and is currently undergoing legal and regulatory cost evaluation. Pending the published final rule, with the NPRM’s proposed revisions to 14 CFR 33.76(c), Safety Recommendation A-10-64 remains classified OPEN--ACCEPTABLE ALTERNATE RESPONSE.

-From Steve Dickson, Administrator: On July 6, 2018, the Federal Aviation Administration (FAA) published the Medium Flocking Bird Test at Climb Condition Notice of Proposed Rulemaking to revise § 33.76 to include an additional certification test, run at a higher airspeed and lower fan speed than the current core ingestion test (83 FR 314 79). The FAA reviewed and responded to public comments received, and a draft final rule is undergoing legal and regulatory cost evaluation. We anticipate the final rule to publish in summer 2020.

I will keep the Board informed of the FAA 's progress on this recommendation and anticipate providing an update by December 2020.

The National Transportation Safety Board (NTSB) has reviewed the Federal Aviation Administration’s (FAA) notice of proposed rulemaking (NPRM) titled, “Medium Flocking Bird [MFB] Test at Climb Condition,” which was published at 83 Federal Register 31479 on July 6, 2018.

The NTSB investigated the January 15, 2009, accident involving US Airways flight 1549, an Airbus A320-214, which experienced an almost total loss of thrust in both engines after encountering a flock of birds and was subsequently ditched on the Hudson River about 8.5 miles from LaGuardia Airport (LGA), New York City, New York. The flight had departed LGA about 2 minutes before the bird encounter occurred; the airplane was at an altitude of 2,818 ft above ground level and a distance of about 4.5 miles north-northwest of the departure end of runway 4 at LGA.

The NTSB determined that the probable cause of this accident was the ingestion of large birds into each engine, which resulted in an almost total loss of thrust in both engines and the subsequent ditching on the Hudson River.2 As a result of its investigation, the NTSB issued numerous safety recommendations, including the following two recommendations to the FAA:

Modify the 14 Code of Federal Regulations 33.76(c) small and medium flocking bird certification test standard to require that the test be conducted using the lowest expected fan speed, instead of 100-percent fan speed, for the minimum climb rate. (A-10-64)

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. (A-10-65)

In its NPRM, the FAA indicated that, as a result of the accident, it began studying how to improve engine durability with respect to engine core bird ingestion. The Aviation Rulemaking Advisory Committee (ARAC) working group produced a report titled,

We previously noted that your aviation rulemaking advisory committee (ARAC) identified potential changes you could make to section 33.76, including adding another test run at a higher airspeed and lower fan speed than the current medium bird core ingestion test, which we said was an acceptable alternative that may satisfy Safety Recommendation A-10-64.

We note that your publication of a notice of proposed rulemaking (NPRM) to revise section 33.76 was delayed because of the executive orders placing a moratorium on new regulations and requiring all pending regulations to be reviewed. You now anticipate the NPRM to be published by September 2018. Pending revisions to Title 14 CFR 33.76(c) that satisfy Safety Recommendation A 10 64, it remains classified OPEN--ACCEPTABLE ALTERNATE RESPONSE.

-From Daniel K. Elwell, Acting Administrator: As noted in our previous letters to the Board dated November 6, 2015, and September 12, 2016, the Federal Aviation Administration (FAA) tasked the Aviation Rulemaking Advisory Committee (ARAC) in March 2013 to review and assess the standards and advisory material for bird ingestion requirements, particularly to determine if the core ingestion element of current§ 33.76(c) is adequate.

Our previous correspondence also discussed the ARAC accepting a report from its sub-committee on February 19, 2015, identifying changes the FAA may make to§ 33.76, including an additional test run at a higher airspeed and lower fan speed than the current medium bird core ingestion test.

We previously noted that the FAA expected to publish by the end of2016 a notice of proposed rulemaking (NPRM) to revise§ 33.76. However, the FAA's rule schedules were revised to account for review, re-prioritization, and evaluation in accordance with Executive Orders 13771 and 13777. Therefore, we now anticipate publication of the NPRM by September 2018. I will keep the Board informed of the FAA's progress on this recommendation and provide an update by April 2019.

We continue to believe that the test element that your aviation rulemaking advisory committee proposed, which is critical for core ingestion in terms of ingested bird mass and rotor and bird speeds, addresses our concerns, and your plan to revise section 33.76(c) to include this additional test constitutes an acceptable alternate solution to this problem. Pending our review of the proposed revisions to 14 CFR 33.76(c) contained in the published notice of proposed rulemaking, Safety Recommendation A 10 64 remains classified OPEN--ACCEPTABLE ALTERNATE RESPONSE.

-From Michael P. Huerta, Administrator: As discussed in our letter dated November 6, 2015, the Federal Aviation Administration (FAA) tasked the Aviation Rulemaking Advisory Committee (ARAC) in March 2013 to review and assess the standards and advisory material for bird ingestion requirements, particularly to determine if the core ingestion element of current§ 33.76(c) is adequate. The ARAC accepted a report from its sub-committee dated February 19, 2015, identifying changes to § 33.76 that include an additional test run at a higher airspeed and lower fan speed than the current medium bird core ingestion test.

We expect to publish a notice of proposed rulemaking by the end of2016 revising§ 33.76 to add this test.

I will keep the Board informed of the FAA ·s progress on this recommendation and provide an update by October 2017.

We note that your aviation rulemaking advisory committee (ARAC) has completed its review of the standards and advisory material for bird ingestion requirements and identified changes to section 33.76(c) that include an additional test run at a higher airspeed and lower fan speed than what is used for the current medium bird core ingestion test. We previously indicated that, as an acceptable alternate solution, you could include an additional test element that you believe would be more critical for core ingestion in terms of ingested bird mass and/or rotor speeds and bird speed. We believe that the test element proposed by the ARAC addresses these concerns.

Therefore, we believe that your plan to include the additional test in section 33.76(c) constitutes an acceptable alternate solution to this problem. Pending the completion of these revisions to 14 CFR 33.76(c), Safety Recommendation A 10 64 remains classified OPEN—ACCEPTABLE ALTERNATE RESPONSE.

-From Michael P. Huerta, Administrator: As discussed in our letter dated December 24, 20 13. the Federal Aviation Administration (FAA) tasked the Aviation Rulemaking Advisory Committee (ARAC) in March 2013 to review and assess the standards and advisory material for bird ingestion requirements, particularly to determine if the core ingestion element of current§ 33.76(c) is adequate. The ARAC accepted a report from its sub-committee dated Februaryl9, 2015, identifying changes to§ 33.76 that include an additional test run at a higher airspeed and lower fan speed than the current medium bird core ingestion test. A copy of this document is enclosed.

The FAA intends to revise§ 33.76 to add this test. I will keep the Board informed of the FAA's progress on Safety Recommendation A-10-64 and provide an update by October 2016.

You have previously stated that you do not believe the test required in 14 CFR Section 33.76(c) should be conducted using the lowest expected fan speed, as recommended. We have replied that your plan for addressing this safety issue (with an additional test element that you believe would be more critical for core ingestion in terms of ingested bird mass and/or rotor speeds and bird speed) could constitute an acceptable alternate solution if the additional test element is effective in solving the problem.

At the present time, your aviation rulemaking advisory committee (ARAC) is reviewing the standards and advisory material for bird ingestion requirements, particularly to determine whether the core ingestion element of Section 33.76(c) is adequate and the need for development of an additional test element that is more critical for core ingestion in terms of ingested bird mass and/or rotor speeds and bird speed. In the meantime, Safety Recommendation A 10 64 remains classified OPEN—ACCEPTABLE ALTERNATE RESPONSE pending issuance of an additional test element for core ingestion that alternately satisfies the recommendation.

-From Michael P. Huerta, Administrator: In March 2013, the Federal Aviation Administration (FAA) tasked an Aviation Rulemaking Advisory Committee (ARAC) to review and assess the standards and advisory material for bird ingestion requirements, particularly to determine if the core ingestion element of content § 33.76(c) is adequate. We expect the ARAC's review will identify changes to make future engine models more tolerant of this threat (e.g., include an additional test element that is more critical for core ingestion in terms of ingested bird mass and/or rotor speeds and bird speed). Scheduled completion for the ARAC's final report is no later than March 31, 2015.

We note that, based on the FAA working group’s review of the safety objectives and test methods for the core ingestion element of the small and medium flocking bird certification test standard, the FAA is considering rulemaking to revise and strengthen the core ingestion element of 14 CFR 33.76(c). The FAA stated that it does not believe that the test should be conducted using the lowest expected fan speed, as recommended. However, we note that the FAA intends to address this safety issue with an additional test element that the FAA believes would be more critical for core ingestion in terms of ingested bird mass and/or rotor speeds and bird speed.

We believe that the FAA’s plan could constitute an acceptable alternate solution if the additional test element addresses these concerns. In the meantime, pending our review of the FAA’s additional test element, Safety Recommendation A-10-64 is classified OPEN—ACCEPTABLE ALTERNATE RESPONSE.

-From Michael P. Huerta, Acting Administrator: A dedicated Federal Aviation Administration (FAA) and Aerospace Industry Association (AIA) working group has completed its evaluation of the safety objective and test methods for the core ingestion element of § 33.76(c), small and medium flocking bi rd. The goal of this evaluation was to determine whether we should apply more critical test conditions to the core element of the current rule. The FAA has reviewed the working group interim report and has concluded that the current medium bird core ingestion certification requirements may not be as rigorous as originally intended.

While the FAA does not agree with the specific details of this safety recommendation (for example, the lowest expected fan speed criteria), we are considering rulemaking to revise and strengthen the core ingestion element of current § 33.76(c). This action would make future engine models more tolerant of this threat by including, for example, an additional test clement that is more critical for core ingestion in terms of ingested bird mass and/or rotor speeds and bird speed.

I will keep the Board informed of the FAA's progress on these safety recommendations and provide an update by July 2013.

The NTSB notes the continued efforts of the working group to evaluate these two recommendations, and we look forward to reviewing the group’s findings. Pending completion of that evaluation and appropriate FAA action to implement the recommended revision, Safety Recommendations A-10-64 and -65 remain classified OPEN—ACCEPTABLE RESPONSE.

- From J. Randolph Babbitt, Administrator: While slower fan speeds may result in greater bird mass into the core for certain designs and under certain circumstances, the Board's recommendation appears to address only the core ingestion sub-element of § 33.76(c). However, the requirement in § 33.76(c) applies to the entire engine, not just the core. Both fan and core ingestion elements of the rule are important, and reducing the fan speed requirement across the board to some minimum value to primarily address core ingestions, will result in a less severe demonstration or overall engine capability.

This is especially true for the takeoff phase, where a power loss due to fan damage is most likely. A multi-engine power loss during this phase, with the airplane low and slow, would allow little time for the crew to respond. Therefore, the Federal Aviation Administration (FAA) believes the takeoff phase is most critical overall for bird ingestion considerations. We agree with the Board's recommendation and have established a working group to further evaluate this recommendation. A dedicated FAA and Aerospace Industry Association (AlA) working group was formed.

The working group is evaluating our test methods and safety objectives for § 33.76(c) to determine if they should apply more critical test conditions to the core ingestion element of the current regulation. At this time, the working group has agreed thaI the core ingestion clement of the overall threat needs closer evaluation against the safety objective and our standard methods of compliance. The working group will conduct this evaluation, which may result in new rulemaking, policy, or method of compliance guidance.

The NTSB looks forward to reviewing the findings of the working group led by the FAA and the Aerospace Industries Association (AIA) that is evaluating these two recommendations. Pending completion of that evaluation and appropriate FAA action to implement the recommended revision, Safety Recommendations A-10-64 and -65 are classified OPEN – ACCEPTABLE RESPONSE.

CC# 201000368: - From J. Randolph Babbitt, Administrator: This recommendation focuses on the core ingestion sub-element of § 33.76(c), even though the requirement in this section applies to the entire engine rather than just the core. For turbofan engine fan stages, high fan rotor speeds at takeoff are more critical to the test outcome in terms of fan damage than the lower fan speeds during climb-out. However, we agree slower fan speeds may result in greater bird mass entering into the core for certain designs and under certain circumstances.

Both elements of § 33.76(c) - fan damage and core ingestion – are important, and reducing the fan speed requirement across the board to primarily address core ingestions would result in a less severe demonstration of overall engine capability. A working group led by the Federal Aviation Administration and Aerospace Industries Association (AIA) plans to evaluate the test methods and objectives of § 33.76(c) to determine if we should apply more critical test conditions to the core ingestion element of the existing rule. New rulemaking, policy, or method of compliance guidance could result from this effort.