By now, everyone has heard about the Southwest Airlines aircraft accident (flight 1380).
The media is reporting that one fan blade was released. Resulting shrapnel appears to have entered the fuselage through a passenger window.
The good news is that this sort of thing is very rare. The bad news is that it happened at all. The important follow-up is that we as an industry must use the data from this tragedy to make aviation even safer.
Whenever this sort of thing happens, PMA holders will want to investigate whether any of their parts were on the aircraft. NTSB officials have told stories about absent parties who were blamed in a probable cause finding because they were absent from the investigation, and it was politically easy to assign blame to an absent party. If your parts were on that engine anywhere then you should already have technical experts assigned to be part of (or to follow) that investigation. And even if you had no parts on that engine, you should be analyzing the root cause to identify what can be learned from this accident, and how we can prevent a future accident from occurring for any related reasons.
The media is also reporting that fan blade had suffered metal fatigue. The FAA has regulations and guidance directing the industry to consider these sort of issues during the design and to mitigate against any damage. If metal fatigue is ultimately identified as a probable cause, then the entire aviation manufacturing industry should be considering strategies for protecting against such failures in the future (and not just in this particular installation).
The engine is identified in the FAA’s registry database as a “CFM56 SERIES” engine, but it is identified more precisely in the media as a CFM56-7B. A review of the FAA’s database suggests that Chromalloy has been approved to make PMA fan blade platforms for this engine, but that no one appears to have been approved to make PMA fan blades for this engine.
At least one prior fan blade failure has occurred in this engine model, resulting in CFM service bulletins (CFM CFM56–7B Service Bulletins Nos. 72–1019, and 72-1024) a proposed FAA Airworthiness Directive that would require an ultrasonic inspection of the CFM56-7B fan blades, and replacement of fan blades that failed the inspection, and an EASA Airworthiness Directive that was issued on March 26, 2018 to implement the CFM service bulletin inspections for European-registered aircraft (it also permits eddy-current inspection as an alternative). The FAA Airworthiness Directive appears to still be pending.
The last U.S. airline fatality occurred on Feb. 12, 2009, when Colgan Air Flight 3407 experienced an aerodynamic stall that was attributed by the NTSB to the captain’s inappropriate response to the activation of the stick shaker.
U.S. commercial aviation has such a great safety record that the entire industry feels the loss deeply whenever there is a fatality. We need to do what we can to ensure that this sort of loss does not recur.
