ANALYSIS OF WING SEPARATION AND MID-AIR BREAKUP IN LIGHT TRAINING AIRCRAFT

Despite increasing discussions concerning the recently published wing spar airworthiness directive (AD) that affects many training aircraft and several current ADs for wing struts, there remains limited objective literature on incidents of wing separation or mid-air breakup. This paper attempts to report and analyse instances of wing separation and mid-air breakup of light training aircraft. A careful review of the United States National Transportation Safety Board (NTSB) aircraft accident database revealed that wing separations were more likely occur as mid-air breakup in PA28s than 172s/182s (OR: 3.06, 95 % CI: 1.3682 to 6.8536, p = .008). Additionally, wing separations were less likely to occur as mid-air breakups in the strutted 172s/182s than 177s/210s that don’t have a wing strut (OR: 0.11, 95 % CI: 0.04 to 0.29, p = <.001). This implies that non-strutted wing designs may be more susceptability to mid-air breakup than the strutted design of similar aircraft.

Oil Fumes, Flight Safety, and the NTSB

During its investigations into a series of ten aircraft crashes from 1979 to 1981, US National Transportation Safety Board (NTSB) officials were presented with a hypothesis that “several” of the crashes could have been caused by pilot impairment from breathing oil fumes inflight. The NTSB and their industry partners ultimately dismissed the hypothesis. The authors reviewed the crash reports, the mechanics of the relevant engine oil seals, and some engine bleed air data to consider whether the dismissal was justified. Four of the nine aircraft crash reports include details which are consistent with pilot impairment caused by breathing oil fumes. None of the tests of ground-based bleed air measurements of a subset of oil-based contaminants generated in the engine type on the crashed aircraft reproduced the inflight conditions that the accident investigators had flagged as potentially unsafe. The NTSB’s conclusion that the hypothesis of pilot incapacitation was “completely without validity” was inconsistent with the evidence. Parties with a commercial conflict of interest should not have played a role in the investigation of their products. There is enough evidence that pilots can be impaired by inhaling oil fumes to motivate more stringent design, operation, and reporting regulations to protect safety of flight.

Installation Errors in Polyethylene Pipe for Natural Gas Service: Recent Case Histories by the National Transportation Safety Board (NTSB)

The National Transportation Safety Board investigated numerous accidents involving the release of natural gas from polyethylene pipelines. The industry manufactures polyethylene pipes and fittings in many shapes and they can be installed/joined in a variety of ways. New grades with improved material properties, such as high-density polyethylene (HDPE) and ultra-high-molecular-weight polyethylene (UHMWPE) have been introduced that show improved material properties compared to their medium-density polyethylene (MDPE) predecessors. However, improved material properties by themselves do not guarantee extended service life of an installed pipe or fitting. Simple errors, whether unintentional, unknown, or unaware by the installer, can lead to a gas leak and possibly a serious accident that causes injury or loss of life. These errors can significantly reduce the service life of a pipe or fitting. The NTSB Materials Laboratory examined several polyethylene service tees that were involved in an accident as a result of a natural gas leak. Examples of gas leakage resulting from failure to follow best practice at installation will be mentioned. Certain service tee assemblies are joined to pipe segments by mechanical methods while others are joined by fusion methods, such as heat fusion or electrofusion process. An example is cited where a manufacturer of a mechanical tapping tee made several versions of the same design that required specific installation instructions that were different from their predecessors. When several versions of the same tee assembly are manufactured by the same company, one should be aware of identifiable features that differentiate one version from another and then carefully use installation instructions that apply to the model that will be installed. Another example is cited where a service tee that was joined by the heat fusion process had been contaminated prior to bonding. Learning from mistakes that are made during installation, through examples, provides a foundation from which we can correct our procedures and avoid repeating the same mistakes in the future.

Adjudication of Symbolic & Connectionist Arguments in Autonomous Driving AI

This paper discusses the tragic accident in which the first pedestrian was killed by an autonomous car: due to several grave errors in its design, it failed to recognize the pedestrian and stop in time to avoid a collision. We start by discussing the accident in some detail, enlightened by the recent publication of a report from the National Transportation Safety Board (NTSB) re. the accident. We then discuss the shortcomings of current autonomous- car technology, and advocate an approach in which several AI agents generate arguments in support of some action, and an adjudicator AI determines which course of action to take. Input to the agents can come from both symbolic reasoning and connectionist-style inference. Either way, underlying each argument and the adjudication process is a proof/argument in the language of a multi-operator modal calculus, which renders transparent both the mechanisms of the AI and accountability when accidents happen.

U.S. Statement of Demonstrated Ability Aeromedical Waivers

INTRODUCTION: The Statement of Demonstrated Ability (SODA) is a type of U.S. aeromedical waiver used for disqualifying conditions that are not expected to change. About 21,000 (2%) U.S. pilots possess a SODA waiver.METHODS: We matched all pilot medical exams from the FAA’s medical certification database from 2002 through 2011 to their respective accidents in the National Transportation Safety Board accident database. The association of SODA waivers and SODA conditions with the odds of an accident were explored using logistic regression techniques.RESULTS: For 3rd class flight exams, the presence of a SODA waiver was not associated with the odds of an accident. For the 1st and 2nd class exams, the accident odds ratio (OR = 1.45) was statistically significant. Crop dusting operations accounted for 17 of the 40 accidents where SODAs were present and returned a significant accident OR = 1.68. SODAs were not associated with the odds of accidents during other commercial operations. Six SODA conditions (amputation, internal eye, external eye, visual fields, bone and joint, and miscellaneous) were also found to have elevated ORs but were based on very small accident counts. NTSB investigators and the authors reviewed all accidents and none thought the SODA condition to be contributory.DISCUSSION: SODA waivers were not associated with increased accident odds except for crop dusting operations. Six specific SODA conditions also had elevated odds of an accident, but there was no evidence they contributed to the accidents. Overall, U.S. pilots with SODA waivers appear to have a satisfactory safety record.Mills WD, Davis JT. U.S. Statement of Demonstrated Ability aeromedical waivers. Aerosp Med Hum Perform. 2019; 90(12):1034–1040.

KERUNTUHAN JEMBATAN AKIBAT KEGAGALAN PELAT BUHUL PADA SAMBUNGAN JEMBATAN RANGKA BAJA (Studi Kasus: Jembatan I-35W MISSISIPI)

ABSTRACTThe collapse of Minnesota Bridge number 9340 or I-35W bridge on August 1, 2007, is indeed surprising considering the maintenance of the bridge conducted regularly. The bridge was designed in the early 1960s using AASHO "Standard Specification for Highway Bridges" 1961 edition with the allowable stress method. Materials used HSLA (high-strength low-alloy) steel. The data on the I-35W bridge obtained from the NTSB (National Transportation Safety Board) report. The analysis to identify the cause of the collapse of the I-35W bridge derived from the results of a review of previous research.The method of analysis referred to is a simple method of Holt and Hartman (2008), FEM by Hao (2010), Liao (2010), and Lora (2013).The finding of the I-35W bridge indicates that the cause is due to the lack of U10 gusset plate capacity, because the thickness of the gusset plate at the joint is the other thinnest gusset plate and its failure due to buckling, and the condition of the gusset plate has been deformation in the construction period. The further adds a substantial buckling.The result of evaluation using simple and FEM method proves that the gusset plate capacity of the U10 joint is inadequate so that the gusset plate overstressed. The collapse pattern of the gusset plate at the U10 joint has similarities between the analysis with FEM and the damage of the real bridge.Keyword: Steel truss bridge, joint, gusset plateABSTRAKKeruntuhan jembatan Minnesota no. 9340 atau jembatan I-35W pada 1 Agustus 2007 sangat mengejutkan mengingat perawatan jembatan ini dilakukan teratur secara berkala. Jembatan ini didesain pada awal tahun 1960an menggunakan peraturan AASHO “Standard Specification for Highway Bridges” edisi 1961 dengan metode tegangan ijin. Material yang digunakan baja mutu tinggi HSLA (high-strength low-alloy). Data-data mengenai jembatan I-35W diperoleh dari laporan NTSB (National Transportation Safety Board). Sedangkan analisis untuk mengidentifikasi penyebab keruntuhan jembatan I-35W diperoleh dari hasil kajian dari penelitian terdahulu. Metode analisis yang diacu adalah metode sederhana dari Holt dan Hartman (2008), metode FEM oleh Hao (2010), Liao (2010), dan Lora (2013).Hasil analisis terhadap keruntuhan jembatan I-35W menunjukkan bahwa penyebab keruntuhan disebabkan kapasitas pelat buhul U10 yang kurang karena ketebalan pelat buhul pada sambungan tersebut paling tipis dibanding pelat buhul yang lain dan keruntuhannya akibat tegangan tekuk yang besar, serta kondisi pelat buhul sudah mengalami deformasi pada saat masa pengkonstruksian. Hal ini makin menambah tekuk yang besar.Hasil evaluasi dengan metode sederhana maupun FEM membuktikan bahwa kapasitas pelat buhul pada sambungan U10 tidak memadai sehingga pelat buhul mengalami overstress. Pola keruntuhan pelat buhul pada sambungan U10 mempunyai kesamaan antara analisis dengan FEM dengan kerusakan jembatan aslinya.Kata Kunci: Jembatan rangka baja, sambungan, pelat buhul