Incident: Boeing 737 NG Pickle Fork Cracking Investigation and Grounding

Published Date: 2019-10-09

Postmortem Analysis
Timeline 1. The software failure incident involving cracks in the pickle fork component of Boeing's 737 Next Generation (NG) aircraft happened in October 2019 [Article 90467].
System unknown
Responsible Organization unknown
Impacted Organization 1. Southwest Airlines [Article 90467] 2. Boeing [Article 90467]
Software Causes unknown
Non-software Causes 1. The failure incident involving Boeing's 737 Next Generation (NG) aircrafts was caused by cracking in a critical component known as the 'pickle fork' that attaches the wings to the plane's fuselage [90467].
Impacts unknown
Preventions 1. Implementing more rigorous quality control measures during the manufacturing process to detect potential defects in critical components like the pickle fork before they are installed on aircraft [90467]. 2. Conducting more thorough and frequent inspections of aircraft components, especially those critical for flight safety, to identify issues like cracking early on [90467]. 3. Enhancing communication and collaboration between aircraft manufacturers like Boeing, regulatory bodies like the FAA, and airlines to ensure prompt reporting and investigation of potential safety concerns [90467].
Fixes 1. Conducting detailed inspections on the affected aircraft to identify and address cracks in the pickle fork component [90467]. 2. Implementing repair plans provided by Boeing to address the issue with the pickle fork component [90467]. 3. Providing necessary parts and technical support to customers for fixing the problem with the pickle fork component [90467]. 4. Following the instructions provided by Boeing for conducting inspections and reporting the results to ensure the safety and quality of the aircraft [90467].
References unknown

Software Taxonomy of Faults

Category Option Rationale
Recurring unknown The articles do not mention any software failure incident related to either one_organization or multiple_organization.
Phase (Design/Operation) design Unknown
Boundary (Internal/External) within_system (a) within_system: The software failure incident related to the cracks in the pickle fork component of Boeing's 737 Next Generation (NG) aircraft is primarily within the system. The cracks were found in a critical component of the aircraft, which is an internal part of the plane's structure designed to manage stress, torque, and aerodynamic forces [90467]. The failure was detected during inspections of the aircraft, indicating an internal issue with the component itself rather than an external factor causing the cracks. The incident led to the grounding of several 737 NGs for inspection and repair, highlighting an internal system failure within the aircraft.
Nature (Human/Non-human) non-human_actions (a) The software failure incident occurring due to non-human actions: - The software failure incident involving the cracking in the pickle fork component of Boeing's 737 Next Generation (NG) aircraft was not directly attributed to human actions but rather to the stress, torque, and aerodynamic forces that the component is designed to manage [90467]. - The cracks in the pickle fork were discovered during inspections, prompting the grounding of some aircraft and an emergency investigation by the Federal Aviation Administration (FAA) [90467]. (b) The software failure incident occurring due to human actions: - The article does not mention any specific human actions that directly contributed to the software failure incident involving the cracking in the pickle fork component of Boeing's 737 Next Generation (NG) aircraft [90467].
Dimension (Hardware/Software) hardware (a) The software failure incident occurring due to hardware: - The article reports that Boeing's 737 Next Generation (NG) aircrafts were grounded due to cracking in a critical hardware component known as the 'pickle fork' which attaches the wings to the plane's fuselage [90467]. - The cracks were found in the outer chord of the rear pickle forks and the behind lying safety straps, indicating a hardware issue in the aircraft structure [90467]. (b) The software failure incident occurring due to software: - There is no mention of the software failure incident being attributed to contributing factors originating in software in the provided article.
Objective (Malicious/Non-malicious) non-malicious The software failure incident related to the Boeing 737 Next Generation (NG) aircrafts grounding was non-malicious in nature. The failure was attributed to cracks found in a critical component known as the 'pickle fork,' which attaches the wings to the plane's fuselage. This issue was discovered during an emergency investigation by the Federal Aviation Administration (FAA) and was not caused by any malicious intent [90467].
Intent (Poor/Accidental Decisions) unknown The articles do not mention any software failure incident related to poor decisions or accidental decisions. Therefore, the intent of the software failure incident in the provided articles is unknown.
Capability (Incompetence/Accidental) unknown The software failure incident related to the Boeing 737 Next Generation (NG) aircrafts being grounded was not due to development incompetence or accidental factors. The incident was primarily caused by cracks found in a critical component known as the 'pickle fork' that attaches the wings to the plane's fuselage. The cracks were discovered during inspections, prompting an emergency investigation by the Federal Aviation Administration (FAA) [Article 90467].
Duration unknown The software failure incident related to the Boeing 737 NG aircrafts being grounded due to cracks in the pickle fork component is not directly related to a software failure. The issue with the pickle fork component is a structural problem rather than a software-related one. Therefore, the duration of the incident cannot be classified as either permanent or temporary based on the information provided in the articles [90467].
Behaviour other (a) crash: The articles do not mention any software crashes as the cause of the failure incident. Therefore, the incident is not related to a crash in the software system [Article 90467]. (b) omission: The incident is not related to the system omitting to perform its intended functions at an instance(s) [Article 90467]. (c) timing: The incident is not related to the system performing its intended functions correctly, but too late or too early [Article 90467]. (d) value: The incident is not related to the system performing its intended functions incorrectly [Article 90467]. (e) byzantine: The incident is not related to the system behaving erroneously with inconsistent responses and interactions [Article 90467]. (f) other: The failure incident in this case is related to a physical issue with the aircraft's pickle fork component, which is not directly related to software behavior. Therefore, the failure does not fall into the categories provided [Article 90467].

IoT System Layer

Layer Option Rationale
Perception None None
Communication None None
Application None None

Other Details

Category Option Rationale
Consequence death, theoretical_consequence (a) death: People lost their lives due to the software failure - The article mentions that Boeing was forced to ground its entire global fleet of the 737 NGs successor, the 737 Max aircraft, following two fatal crashes in Indonesia and Ethiopia that left 346 dead [Article 90467]. (h) theoretical_consequence: There were potential consequences discussed of the software failure that did not occur - The article discusses the dire consequences that could occur if the cracked pickle forks in the 737 NGs were to fail mid-flight, although no crashes or incidents have yet been attributed to the issue [Article 90467].
Domain transportation The failed system in the reported incident was related to the transportation industry, specifically the aviation sector. The software failure incident involved Boeing's 737 Next Generation (NG) aircraft, where cracks were discovered in a critical component known as the 'pickle fork' that attaches the wings to the plane's fuselage [Article 90467]. This incident led to the grounding of several 737 NG aircraft and prompted an emergency investigation by the Federal Aviation Administration (FAA) [Article 90467]. Southwest Airlines confirmed that two of its 737 NGs were grounded due to cracking in the pickle fork component [Article 90467]. Additionally, the article mentions that the 737 NG models are operated by airlines such as American Airlines, United, and Delta [Article 90467].

Sources

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