民机燃油箱防爆闪电防护新适航要求研究

民用飞机燃油箱系统防爆设计是飞机设计的一个重要方面,其中适航对燃油箱系统闪电防护设计要求作为燃油箱防爆设计及验证的一个重要组成部分,历来受到航空工业界及美国联邦航空局(FAA)的普遍关注。通过研究FAA 关于民用飞机燃油箱系统防爆方面闪电防护的最新适航要求,总结了相关条款的变化内容及相应的符合性验证方法,并预判了未来航空工业界由此产生的影响,对民用飞机适航验证有一定借鉴意义。     

3D visualization to support airport security operations

In the summer of 2000, the National Safe Skies Alliance awarded a project to the Applied Visualization Center at the University of Tennessee to develop a 3D computer tool to assist the US Federal Aviation Administration security group, now the Transportation Security Administration, in evaluating new equipment and procedures to improve airport checkpoint security. At the time of this writing, numerous detection equipment models, three specific airports, and a placement and passenger flow simulation tool for airport security planners have been developed. Similar tools have been constructed for simulating cargo/baggage inspection and other airport security operations. An extension of the original effort to consolidate the tools is currently underway.     

民用飞机燃油箱系统闪电防护分析方法研究

民机燃油箱系统的闪电防护是燃油箱安全的重要研究范畴,本文依据FAA的25-146号修正案和咨询通告AC25.954-1,介绍了民用飞机燃油箱系统闪电防护分析方法。在点火源防护分析思路的基础上,针对闪电引起的点火源,在明确飞机闪电分区后,可通过容错类设计或非容错类设计分别开展分析。针对容错类设计,可仅通过证明防护设计特征有效且可靠来表明符合性,无需进一步分析失效概率。针对非容错类设计,通过定性和定量分析法进行评估。在定性分析时,需评估非容错特征失效且引起点火源的概率小于1E-5。在定量分析中,可结合燃油箱可燃性、关键闪电和防护特征失效概率确保闪电引起燃油蒸气点燃的概率为极不可能。同时,根据闪电环境定义的电流振幅和波形对防护设计特征进行有效性验证。     

Highly efficient computation method for hazard quantification of uncontained rotor failure

Uncontained Engine Rotor Failure (UERF) can cause a catastrophic failure of an aircraft, and the quantitative assessment of the hazards related to UERF is a very important part of safety analysis. However, the procedure for hazard quantification of UERF recommended by the Federal Aviation Administration in advisory circular AC20-128A is cumbersome, as it involves building auxiliary lines and curve projections. To improve the efficiency and general applicability of the risk angle calculation, a boundary discretization method is developed that involves discretizing the geometry of the target part/structure into node points and calculating the risk angles numerically by iterating a particular algorithm over each node point. The improved efficiency and excellent accuracy for the developed algorithm was validated through a comparison with manual solutions for the hazard quantification of the engine nacelle structures of a passenger aircraft using the guidance in AC20-128A. To further demonstrate the applicability of the boundary discretization method, the proposed algorithm was used to examine the influence of the target size and the distance between the target and rotor on the hazard probability.     

民用飞机飞行操纵系统对CCAR25.671(d)条款符合性的适航验证方法分析

CCAR25.671(d)规定飞机的设计必须使其在所有发动机都失效时仍可操纵.针对中国民用航空总局颁发的运输类飞机适航标准(CCAR25部)的上述要求,某民用飞机对其飞行操纵系统提出了采用试飞(MOC6)和工程模拟器(MOC8)试验验证的方法.首先阐述了美国FAA航空规章制定咨询委员会(ARAC)对CCAR25.671...     

飞机设计中发动机转子碎片非包容性设计

基于一种双发常规布局飞机进行飞机设计中发动机转子碎片非包容失效设计的研究,通过研究相关适航规章,以及相关咨询通告等文件,得出第3节到第7节所描述的对咨询通告AC20-128A适当裁剪的工程方法和步骤,并在实例机型设计中进行验证,缩短了飞机研制周期的同时,也表明在发动机转子碎片非包容失效事故发生后,飞机系统及机体结构等采取的设计措施、防范措施符合相关适航条例要求,也即结构剩余的强度、灾难性事件发生概率等满足AC20-128A第10条c中的定性和定量要求,表明该型实例飞机完全满足相关适航条例的要求,并获得中国民用航空局(CAAC)和美国联邦航空局(FAA)的认可。     

大型民用飞机货舱哈龙替代品抑制及灭火系统研究

基于美国联邦航空局休斯研究中心环保型飞机货舱哈龙替代品抑制及灭火的研究,阐释了飞机货舱哈龙替代品抑制及灭火系统最低性能标准,总结了氮气、气溶胶、细水雾等三种机载灭火系统最新研究成果,剖析了大型民用飞机货舱哈龙替代品抑制及灭火系统的最新发展趋势,分析了三种哈龙替代品抑制及灭火系统用于飞机货舱的可行性,旨在为我国大型民用飞机货舱哈龙替代品抑制及灭火系统研究提供工程技术参考。     

运输类飞机动力装置溅水试验技术

基于对中国民用航空局（CAAC）运输类飞机适航标准和美国联邦航空管理局（FAA）咨询通告的分析、解读,分别从工程试验与适航验证两个方面,研究了溅水试验程序、试验水池方案设计与滑行速度测量与控制技术,制定了符合适航标准体系的运输类飞机动力装置溅水试验审定程序,以ARJ21-700型支线飞机合格审定试飞为平台,完整进行了相关试验验证。结果表明:所设计的溅水试验程序合理可行,能够完整地验证运输类飞机在机场跑道积水环境下动力装置对适航标准体系的符合性;试飞结果表明CF34-10A发动机配装ARJ21-700型飞机在机场积水环境下起飞构型临界滑行速度为166.6 km/h,发动机风扇、压气机及动力涡轮前温度最大波动值分别为5.1%、1.7%和39 ℃;在飞机着陆构型下,发动机慢车状态相对于最大反推力状态工作稳定性较好,能够满足适航标准规定;项目形成溅水试验程序和技术为后续C919、C929等运输类飞机动力装置相关试验提供了直接的支持。      

运输类飞机防止广布疲劳损伤的新规章解读

 针对运输类飞机结构广布疲劳损伤(WFD),跟踪和总结了国内外所开展的一些重要行动及其结果,客观地分析了现行的有关疲劳损伤的适航规章在执行中存在的不安全因素,指出现行的适航要求和长期依赖已有检查手段对维持飞机超出某一期限后的持续适航是不充分的,会产生不可接受的结构破坏和相关事故的危险性,需要对WFD在其发生之前采取主动的预先解决方法。对WFD检查的革新性的改变导致了针对WFD的适航条例的修正。对美国联邦航空管理局(FAA)提议的针对WFD的规章修正案草案中关于设计批准书持有人的行动及其相关的符合性方法作了分析和解读,重点阐明了新规章对WFD的适用性以及在新规章下要求的飞机WFD评定的方法和过程,包括WFD开始检查点和结构更改点的确定、飞机使用限制（初始使用限制和延伸使用限制）的建立、适航限制条款的建立和修订等。在此基础上,提出了当前乃至今后中国民机结构损伤容限设计和分析新的研究方向。     

中美航空市场自由化进程及其对市场的影响研究

中国-美国航空市场的自由化进程,是中国国际航空市场政策演变的典型代表,其发展趋势对远程宽体客机的市场走向也具有重大影响。2003年,中国民航局提出逐步开放航空市场的目标,并开始融入国际航空市场自由化的潮流,自此,中国民航开始调整国际政策以支持航空自由化和国际合作。但是,中国枢纽的发展目标仍然受到了来自邻国—首尔和东京枢纽的激烈竞争。2004年和2007年签署的协议对中美航空市场产生了深远的影响,旅客运输量有了惊人的增长,市场竞争也显著加强。     

Data-driven reliability analysis of Boeing 787 Dreamliner

The Boeing 787 Dreamliner, launched in 2011, was presented as a game changer in air travel. With the aim of producing an efficient, mid-size, wide-body plane, Boeing initiated innovations in product and process design, supply chain operation, and risk management. Nevertheless, there were reliability issues from the start, and the plane was grounded by the U.S. Federal Aviation Administration (FAA) in 2013, due to safety problems associated with Li-ion battery fires. This paper chronicles events associated with the aircraft’s initial reliability challenges. The manufacturing, supply chain, and organizational factors that contributed to these problems are assessed based on FAA data. Recommendations and lessons learned are provided for the benefit of engineers and managers who will be engaged in future complex systems development.     

Application of Ground/Air Data Link to General Aviation Operations

The Federal Aviation Administration (FAA) is currently upgrading secondary surveillance radars with systems which will have an integral data link capability, the Mode Select (Mode S) beacon system. These new systems will allow two-way data communications between ground systems (e.g., weather databases and Air Traffic Control (ATC) systems) and aircraft that are equipped with data link compatible Mode S transponders and suitable display and input devices. Initial data link services include both weather information and ATC advisories. The MITRE Corporation* is developing an in-house capability to perform end-to-end operational evaluation of data link services. Initially, a low-cost, portable pilot position man-machine interface is being developed for use in general aviation operations. The objective is to explore operational issues in laboratory and limited flight test environments, and to demonstrate these services on a data link I/O device, a laptop portable personal computer (PC) with touch panel. A group of pilots will bench test the interface design, and the results will be incorporated into the design used in flight testing. This paper describes the project's objectives and results to date, including implementation details and pilot test results.     

Microstructural characterization and mechanical behavior analysis of 7075-T6 aluminum subjected to simulated lightning strikes

Aircrafts damages caused by lightning strikes have been known since the early days of aviation. However, the physical effects on the aircraft structure are still being investigated. This work seeks to evaluate the lightning strike effects in the aluminum alloy 7075-T6. Samples were submitted to lightning strike simulation in laboratory and the damages evaluated through characterization techniques. Ultrasound and profilometry tests have shown material loss to 0.272 mm depth in the damaged region. In addition, it was detected the material accumulation occurrence in the damage vicinity of the region. Below the damage, it was found a region where metallurgical changes were identified. The tensile and microhardness tests results have shown reduction in the percentage elongation and hardness increasing in the material affected by lightning. These results are corroborated by the X-Ray Diffraction (XRD) and Rietveld Method (red line) that indicated an increasing in dislocation density and micro-deformation in the material matrix. Optical microscopy results have shown the presence of microcracks on the normal and cross-section surface of the samples damaged. The Energy Dispersive X-Ray Spectroscopy (EDXS) and Electron Backscattered Diffraction Test (EBSD) found coarse intermetallic phases and precipitates compounds with dimensions greater than 1 μm in length. They were responsible for nucleation of the microcracks that propagate along the material grain boundaries.     

Full-scale crash test and FEM simulation of a crashworthy helicopter seat

Crashworthy seat structure with considerable energy absorption capacity is a key component for aircraft to improve its crashworthiness and occupant survivability in emergencies.According to Federal Aviation Administration(FAA) regulations,seat performance must be certified by dynamic crash test which is quite expensive and time-consuming.For this reason,numerical simulation is a more efficient and economical approach to provide the possibility to assess seat performances and predict occupant responses.A numerical simulation of the crashworthy seat structure was presented and the results were also compared with the full-scale crash test data.In the numerical simulation,a full-scale three-dimensional finite element model of the seat/occupant structure was developed using a nonlinear and explicit dynamic finite element code LS-DYNA3D.Emphasis of the numerical simulation was on predicting the dynamic response of seat/occupant system,including the occupant motion which may lead to injuries,the occupant acceleration-time histories,and the energy absorbing behavior of the energy absorbers.The agreement between the simulation and the physical test suggestes that the developed numerical simulation can be a feasible substitute for the dynamic crash test.      

A discrete event systems approach to discriminating intermittent from permanent faults

Almost all work on model-based diagnosis （MBD） potentially presumes faults are per- sistent and does not take intermittent faults （IFs） into account. Therefore, it is common for diag- nosis systems to misjudge IFs as permanent faults （PFs）, which are the major cause of the problems of false alarms, cannot duplication and no fault found in aircraft avionics. To address this problem, a new fault model which includes PFs and IFs is presented based on discrete event systems （DESs）. Thereafter, an approach is given to discriminate between PFs and IFs by diagnosing the current fault. In this paper, the regulations of （PFs and IFs） fault evolution through fault and reset events along the traces of system are studied, and then label propagation function is modified to account for PFs and the dynamic behavior of IFs and diagnosability of PFs and IFs are defined. Finally, illustrative examples are presented to demonstrate the proposed approach, and the analysis results show the fault types can be discriminated within bounded delay if the system is diagnosable.