NTSB and ARAC provide input
Turbine Test for Climb
One commentator made the fair comment that the above Notice of PROPOSED Rule Making was issued nine years after the Miracle on the Hudson. The NTSB issued its findings on US Airways 1549 in 2013 and they included :
Modify the small and medium flocking bird certification test standard in Joint Aviation Regulations Engines to require that the test be conducted using the lowest expected fan speed, instead of 100-percent fan speed, for the minimum climb rate
The Administrator, in 2013, assigned the task of studying Engine Bird Ingestion Requirements to the Aviation Rulemaking Advisory Committee; in 2015, working group produced a report titled, ‘‘Turbofan Bird Ingestion Regulation Engine Harmonization Working Group Report’’. This document reflected a thorough safety risk analysis and recommended, from a list of six options, a test to identify the capacity of the core of the turbine to ingest a flock of birds without stalling:
“Conduct the existing test; then add a new and separate core test using a single bird at climb conditions.”
The amendment to 14 CFR § 33.76, proposed by the FAA after the ARAC and NTSB inputs, added another phase to the testing:
“The first test condition is at a speed of 250-knots, with the engine fan set at the speed associated with the lowest expected climb setting for the engine while the airplane is climbing through 3,000 feet above ground level.
The second test condition, should the applicant determine that no bird mass will enter the core during the test at the climb condition, must be successfully conducted at a speed of 200-knots indicated airspeed, with the engine fan set at the lowest expected mechanical fan speed while the airplane is descending through 3,000 feet AGL on approach to landing. The post-test runon requirements would consist of the final seven minutes of the existing LFB 20-minute post-ingestion run-on requirement (§ 33.76(d)(5)) based on the assumption that the airplane would already be lined up with the run.”
The new condition better replicates the conditions of a bird strike in the climb condition
This video provides an excellent explanation of the impact of a flock ingestion—
Obviously, the time required to better articulate the certification standard.
This change, once the final rule is issued, will apply to prospective certification of engines. In that the development of this regulation has involved experts, OEMs, operators and the JAA, the review process may not require 2-5 years of comments, revisions, reissuance, help from DoT and OMB and finally the promulgation of the “perfect” § 33.76.
While this prospective certification basis will reduce the risk of turbine engines stalling for the next generation of powerplants, the regulation does not apply to the existing fleet, like the US Airways A-320. Industry and the aviation authorities will have to design procedures—engine control/lift management, new technology for detection of birds, zoning (prohibiting location of bird attractions near airports [i.e. garbage dumps] and wildlife management—which will minimize these hazardous bird-plane interactions. The costs of retrofitting all of these powerplants will not meet the OMB B/CA test; so these collateral tactics will need to be developed.
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