MAX将在复飞前进行机身面板检查
定于2月26日发布的美联航指令草案要求波音737 MAX在复飞之前进行检查和修改，以确保发动机控制线路具有足够的电磁干扰防护能力。
An FAA draft directive set for publication Feb. 26 calls for Boeing 737 MAXs to undergo inspections and modifications before further flight to ensure engine-control wiring has adequate protection from electromagnetic interference.
这是波音在两次致命事故以及该机型于2019年3月停飞后对MAX进行的审查中发现的问题，该问题影响了复合材料发动机机舱面板。在生产过程中，位于发动机顶部的一些缩略图整流罩和中间支柱整流罩板面板内部的保护性箔衬里留有空隙，用于屏蔽底层线路。
The issue, discovered during Boeing’s review of the MAX following two fatal accidents and the model’s March 2019 grounding, affects composite engine nacelle panels. During production, gaps were left in protective foil lining inside some thumbnail and mid-strut fairing panels, located on top of the engine, meant to shield wires located just below.
波音于2019年12月11日发布了特别注意服务公告，建议运营商在六个月内检查该区域并修改缩略图整流罩组件。美国联邦航空局（FAA）的适航指令草案（AD）要求“在进一步飞行前”完成这项工作，这使得MAX运营商很可能会选择在该机型获准复飞前解决这一问题，即使其他监管机构预计将采用的指令尚未最终敲定。
Boeing issued a special-attention service bulletin on Dec. 11, 2019 recommending that operators inspect the areas and modify the thumbnail fairing assembly within six months. The FAA’s draft airworthiness directive (AD) calls for the work to be done “before further flight,” making it likely that MAX operators will opt to tackle it before the model is cleared to fly again, even if the mandate—which other regulators are expected to adopt—is not finalized.
美联航的指令将适用于所有MAX飞机。波音的公告按顺序列出了2018年2月至2019年6月制造的一部分飞机，该公司认为这些飞机存在问题。
The FAA directive will apply to all MAXs. Boeing’s bulletin listed a subset of aircraft by serial number built from February 2018 through June 2019 that it believes have the issue.
美联航的草案解释说：对整流罩的“过度返工”可能会导致整流罩内部的铝箔被割破。“该金属层用作飞机布线屏蔽层的一部分，包括与发动机控制系统相关的布线。根据金属层的大小和位置，对金属层进行切割可能导致[高强度辐射场]暴露或闪电附着的可能性，从而通过飞机布线（包括与发动机控制系统相关的布线）发出“假信号”。这种假信号可能会导致发动机推力控制丧失。”
“Excessive rework of the surface of the metallic (aluminum foil) inner layer of those panels can result in cuts to that layer,” the FAA draft rule explained. “This metallic layer functions as part of the shielding for aircraft wiring, including wiring associated with the engine control systems. Cuts to the metallic layer, depending on their size and location, could create the potential for [high intensity radiated fields] exposure or lightning attachment to induce spurious signals onto the underlying airplane wiring, including wiring associated with the engine control systems. Such spurious signals could cause a loss of engine thrust control.”
波音将按保修条款负责所有工作。该制造商还计划修改其库存的准备交付给客户的飞机。
Boeing is covering all work under warranty. The manufacturer also plans to modify aircraft it has in storage awaiting delivery to customers.
该制造商说：“在飞机的缩略图整流罩和中间支柱整流罩面板上发现问题的运营商将需要用波音提供的新面板替换旧面板。”“波音还要求所有MAX运营商更换复合面板上的缩略图连接组件，并涂抹密封剂，以建立所需的电气粘接路径。波音将提供零件，以确保粘结路径按预期工作。我们现在正在与客户协调，以便在预计恢复服务（RTS）时间线之前完成工作。”
“Operators who find the issue on the airplane’s thumbnail and mid-strut fairing panels will need to replace the panels with new ones provided by Boeing,” the manufacturer said. “Boeing is also asking all MAX operators to replace the thumbnail landing assemblies on the composite panels and apply a sealant to establish a required electrical bond path. Boeing will provide the parts to ensure the bond path works as intended. We are now coordinating with our customers to complete the work prior to our estimated return to service (RTS) time line.”
最早由《西雅图时报》报道的机舱面板问题是波音和监管机构在审查MAX的设计和认证时指出的几个问题之一。机舱面板的修改将增加复飞前的一系列维修工作，其中包括修改后的飞行控制计算机软件和飞行员培训。
The nacelle panel problem, first reported by the Seattle Times, is one of several that Boeing and regulators have flagged during their reviews of the MAX’s design and certification. The nacelle-panel modification adds to a list of pre-service-return fixes that includes modified flight-control computer software and pilot training.
监管审查以及对狮航610航班2018年10月坠机事件和2019年3月埃航302航班事故的持续调查提示要进行软件和培训变更，具体日程有待最终确定。波音错误地假设飞行员将如何应对MAX未经机动特性增强系统（MCAS）飞行控制法则授权的俯冲输入，以及该功能依赖于单一迎角传感器馈送的数据，是造成两起事故的罪魁祸首。修改MCAS软件是波音修复工作的主要重点，但是错误的假设促使美联航要求对MAX进行广泛的评估，而不仅限于与事故相关的因素。
The software and training changes, which still must be finalized, were prompted by regulatory reviews as well as the investigation into the October 2018 crash of Lion Air Flight 610 and a still-ongoing probe of the March 2019 Ethiopian Airlines Flight 302 accident. Boeing’s erroneous assumptions about how pilots would react to uncommanded nose-down inputs by the MAX’s maneuvering characteristics augmentation system (MCAS) flight control law, and the function’s reliance on a single angle-of-attack sensor feed, set the stage for both accidents. Modifying the MCAS software is the primary focus of Boeing’s fixes, but the erroneous assumptions prompted the FAA to order an extensive evaluation of the MAX that went beyond factors linked to the accidents.
波音正在解决的另一个问题：检查MAX燃油箱和其他安全关键区域是否有异物碎片（FOD）。该问题在例行检查期间浮出水面，并在随后的检查中发现了更多实例，于是决定将其应用于整个库存机队。波音表示，将对其MAX生产工艺进行更改，以纳入更多FOD预防措施，特别是在燃料电池领域。波音拒绝透露FOD检查结果。
Another issue that Boeing is addressing: inspections of MAX fuel tanks and other safety-critical areas for foreign object debris (FOD). That issue surfaced during routine inspections and are being applied to the entire stored fleet after subsequent checks turned up more instances. Boeing said that its MAX production process will be changed to include more precautions to prevent FOD, particularly in fuel-cell areas. Boeing declined to provide an update on the FOD inspections’ findings.
波音在第二次事故发生后立即停止了MAX的交付，并于1月份暂停了MAX的生产。目前已经制造了约800架MAX，其中有387架在客户手中，还有400架是波音停止交付后生产的。
Boeing halted MAX deliveries just after the second accident, and in January suspended MAX production. About 800 MAXs have been built, including 387 in customers’ hands and 400 that Boeing produced after it stopped deliveries.
这条消息是Sean Broderick在Aviation Daily发表的文章。《Aviation Daily》为关注商业航空的高管提供真知灼见。每天获取航空公司和机场策略、主要航空公司的数据快照、票价数据以及国际覆盖率。点击此处查看有关Aviation Daily更多消息 ，并申请产品样品。