美國聯邦航空管理局發布緊急適航指令，要求各航空公司利用熱聲成像技術檢查波音777飛機上普惠引擎是否存在裂紋。
全文共567個詞，by Claire Bushey in Chicago
US aviation regulators have ordered airlines to inspect certain Pratt & Whitney engines on Boeing jets for invisible cracks before the planes are flown again.
美國航空監管機構下令，要求各航空公司檢查波音(Boeing)飛機的普惠(Pratt & Whitney)引擎是否存在肉眼難以發現的裂紋，然後再讓這些飛機重新執飛。
The US Federal Aviation Administration issued an emergency airworthiness directive on Tuesday related to the PW4000-112, an engine used in about 8 per cent of Boeing’s 777 aircraft. The order came three days after an engine on a 777 broke apart four minutes after take-off, scattering debris over a Denver suburb.
美國聯邦航空管理局(FAA)周二發布了一項關於PW4000-112引擎的緊急適航指令。約8%的波音777飛機使用該引擎。在下達這一命令3天前，一架使用該引擎的波音777飛機在起飛4分鐘後引擎破裂，碎片飄落到丹佛郊區。
Photo credit: Getty Images
No one aboard United Airlines flight 328 or on the ground was injured, but planes using the engines from P&W, a division of Raytheon Technologies, were effectively grounded in the wake of the incident.
美國聯合航空公司(United Airlines) 328航班機上人員與地面人員均未受傷，但事故發生後，使用這款普惠引擎的飛機實際上均已停飛。普惠是雷神技術(Raytheon Technologies)的子公司。
Investigators from the National Transportation Safety Board said on Monday that a fan blade in the turbine showed signs of 「metal fatigue」, which appeared to have caused it to snap off at the root. The severed blade hit a second blade, cutting it in half.
美國國家運輸安全委員會(National Transportation Safety Board)的調查人員周一表示，該渦輪的一片扇葉顯示出「金屬疲勞」的跡象，這似乎是導致其從根部斷裂的原因。斷裂的扇葉擊中另一片扇葉，將其切成兩半。
The order called for aircraft operators to conduct a thermal acoustic image inspection of the titanium fan blades at the front of each engine. The 「technology can detect cracks on the interior surfaces of the hollow fan blades or in areas that cannot be seen during a visual inspection」, the FAA said.
這一命令要求各航空公司對每個引擎前端的鈦扇葉進行熱聲成像檢查。美國聯邦航空管理局說，這項「技術可以檢測到空心扇葉內表面或肉眼無法看到的區域的裂紋。」
Regulations currently require the engine to be inspected every 6,500 flight cycles — defined as one take-off and one landing. The FAA said it might establish a shorter inspection interval based on the results from airlines』 initial engine checks.
目前監管規定要求每6500個飛行周期檢查一次這款引擎，一個飛行周期包括一次起飛和一次著陸。美國聯邦航空管理局表示，可能會根據航空公司的初步引擎檢查結果縮短檢查間隔。
Photo credit: Getty Images
The PW4000-112 debuted in 1995 as the launch engine for the 777, but the engine has not been used in the Boeing wide-body jets since the mid-2000s.
PW4000-112於1995年作為波音777的引擎首次亮相，但自2000年代中期以來，該引擎一直未被用於這款波音寬體客機。
Saturday’s incident in the skies above Colorado was not the first alarming episode involving the engine. Fan blades broke off of a turbine in December on a Japan Airlines flight, and in 2018 on a United flight to Hawaii.
上周六科羅拉多州上空發生的事故並不是第一起關於這款引擎的警示事件。去年12月，一架日本航空(Japan Airlines)飛機的渦輪葉片脫落；2018年，一架飛往夏威夷的美聯航飛機也發生此類事故。
Photo credit: Getty Images
NTSB investigators found in the Hawaii incident — where no one was injured — that fatigue had made a tiny crack inside the hollow core fan blade. The crack was noted during an inspection in 2010 and then again in 2015, when it was larger.
美國國家運輸安全委員會的調查人員在夏威夷事故（該事故中無人受傷）中發現，空心葉片內部由於金屬疲勞而出現了一條微小的裂縫。2010年的一次檢查和2015年的一次檢查分別都發現了這種裂縫，但2015年那次發現的裂縫更大。
「The inspectors attributed the indication to a defect in the paint that was used during the [thermal acoustic imaging] process and allowed the blade to continue the overhaul process and be returned to service,」 the NTSB report said.
國家運輸安全委員會的報告顯示：「檢查人員認為這一現象的成因是（熱聲成像）過程中使用的油漆存在缺陷，他們允許葉片繼續進行檢修，然後恢復使用。」
The report found that inspectors primarily received on-the-job training, which 「could adversely impact the inspection. P&W has advised that it was working to correct those issues」.
報告發現，檢查人員主要接受的是在職培訓，這「可能對檢查造成不利影響。普惠公司已表示，正在努力糾正這些問題」。
本文2月24日發布於FT中文網，英文原題為 FAA orders Pratt & Whitney engines be inspected for cracks
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