{"id":32148289,"date":"2026-11-10T16:33:18","date_gmt":"2026-11-10T15:33:18","guid":{"rendered":"https:\/\/migflug.com\/afterburner\/full-scale-fatigue-test-boeing-777-9-limit-of-validity-wfd\/"},"modified":"2026-11-10T16:33:59","modified_gmt":"2026-11-10T15:33:59","slug":"full-scale-fatigue-test-boeing-777-9-limit-of-validity-wfd","status":"publish","type":"post","link":"https:\/\/migflug.com\/afterburner\/fr\/full-scale-fatigue-test-boeing-777-9-limit-of-validity-wfd\/","title":{"rendered":"Boeing 777-9 Fatigue Test: The Rig That Runs for Years"},"content":{"rendered":"<style>.et_pb_title_container h1.entry-title { padding-top: 40px !important; }<\/style>\r\n<!-- mfsh:top -->\r\n\r\n<style>\r\n.mfsh-trigger{display:inline-flex;align-items:center;gap:10px;height:44px;padding:0 18px;margin:0 0 26px;border:2px solid 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It will never leave the ground. It has no engines, no paint and no passengers. It is the fourth 777-9 Boeing built, and it was rolled out of the factory and straight into a rig that will spend years pretending to be the sky.<\/p>\r\n\r\n<p>Most people know about the other test, the one that makes the news: wings bent upward until they snap, a bang, applause from engineers in high-visibility vests. That test lasts minutes and answers one question, which is how hard you can pull before something breaks. This rig answers a different and much harder one. Not how hard. How many times.<\/p>\r\n\r\n<p>And unlike the static test, the fatigue rig is not a demonstration. Under 14 CFR 25.571(b) it is the only acceptable way to establish the number that decides how long the entire fleet may legally keep flying.<\/p>\r\n\r\n\r\n<div style=\"background:#f8f9fa;border-left:4px solid #5C91FF;padding:18px 22px;margin:26px 0 30px;font-size:15px;line-height:1.7\"><p style=\"margin:0 0 10px;font-weight:600;color:#0d1117;font-size:17px\">Quick Facts<\/p><ul style=\"margin:0;padding-left:20px\"><li style=\"margin:4px 0\"><strong>The rule:<\/strong> 14 CFR 25.571(b) requires a limit of validity to be established, and states that the demonstration must be by full-scale fatigue test evidence<\/li><li style=\"margin:4px 0\"><strong>The guidance:<\/strong> FAA Advisory Circular 25.571-1D, Damage Tolerance and Fatigue Evaluation of Structure, dated 13 January 2011<\/li><li style=\"margin:4px 0\"><strong>What the LOV is:<\/strong> the period, in flight cycles or flight hours or both, up to which it has been demonstrated that widespread fatigue damage will not occur in the airplane structure<\/li><li style=\"margin:4px 0\"><strong>The current example:<\/strong> the fourth Boeing 777-9 built is being cycled to 120,000 complete simulated flights, and had passed 63,000 cycles when Boeing published its account in July 2026<\/li><li style=\"margin:4px 0\"><strong>Rate:<\/strong> the rig averages roughly 160 simulated flights in 24 hours, according to Boeing<\/li><li style=\"margin:4px 0\"><strong>Safe-life scatter factor:<\/strong> AC 25.571-1D gives base scatter factors of BSF1 equal to 3.0 and BSF2 of 3.0 or greater for safe-life determination<\/li><li style=\"margin:4px 0\"><strong>What happens afterwards:<\/strong> teardown inspection, in which the test article is disassembled and inspected destructively to find cracks nobody could see from outside<\/li><\/ul><\/div>\r\n\r\n\r\n<h2 style=\"padding-top:22px\">The problem the rig exists to solve<\/h2>\r\n\r\n<p>Fatigue damage is progressive. AC 25.571-1D puts it plainly: it begins as minute cracks, and those cracks grow under repeated stresses. It can start from normal operation and design attributes, or from a material defect, poor fabrication, a corrosion pit, a ding or a scratch. Dealt with one crack at a time, it is a maintenance problem and inspection handles it.<\/p>\r\n\r\n<p>Widespread fatigue damage is a different animal. It is what happens when the same detail, repeated across a large area at similar stress levels, starts cracking everywhere at once. A single rivet line of a lap splice has hundreds of identical holes under identical loads. When that structure goes, it does not go at one hole. The FAA&rsquo;s position on this is uncompromising, and it is the reason the whole regulatory apparatus exists: inspection methods cannot be relied on solely to ensure the continued airworthiness of airplanes indefinitely.<\/p>\r\n\r\n<p>Which creates an unbounded problem. If the only way to prevent widespread fatigue damage forever is to keep modifying and replacing structure forever, then establishing every modification an airframe will ever need is a question with no end. The FAA&rsquo;s answer was to bound it: stop asking how to keep an aeroplane flying indefinitely, and start asking how long the engineering data behind its maintenance programme can be trusted. That number is the limit of validity.<\/p>\r\n\r\n\r\n<div style=\"background:#f8f9fa;border-left:4px solid #1565c0;padding:20px 22px;margin:18px 0 24px;font-size:16px;line-height:1.7;display:flex;gap:20px;align-items:flex-start\"><div><em>&ldquo;An LOV must be established that corresponds to the period of time, stated as a number of total accumulated flight cycles or flight hours or both, during which it is demonstrated that widespread fatigue damage will not occur in the airplane structure. This demonstration must be by full-scale fatigue test evidence.&rdquo;<\/em><div style=\"margin-top:10px;font-size:14px;color:#555\"><strong>14 CFR 25.571(b)<\/strong> &mdash; Damage-tolerance and fatigue evaluation of structure<\/div><\/div><\/div>\r\n\r\n\r\n<p>Two sentences, and the second one is why the rig is built. Not analysis. Not a similar aeroplane. Test evidence, from a full-scale article.<\/p>\r\n\r\n\r\n<figure class=\"wp-block-image size-large\" style=\"margin:0 0 24px;width:100%\"><img decoding=\"async\" class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" width=\"1024\" src=\"https:\/\/migflug.com\/afterburner\/wp-content\/uploads\/sites\/4\/2026\/11\/boeing-777-9-fatigue-test-rig-aerial-everett.jpg\" alt=\"Aerial view of the Boeing 777-9 full-scale fatigue test rig at Everett\" style=\"width:100%;height:auto;max-width:100%;display:block\"><figcaption style=\"font-size:13px;color:#777;text-align:center;margin-top:6px;font-style:italic\">The 777-9 fatigue rig seen from above at Everett, Washington. The airframe inside is the fourth 777-9 built, delivered from the factory straight into the structure. Photo: Boeing \/ Patrick Rodwell<\/figcaption><\/figure>\r\n\r\n\r\n<h2 style=\"padding-top:22px\">What the test actually does<\/h2>\r\n\r\n<p>Appendix 2 of AC 25.571-1D describes it as a laboratory test in which structure representative of the type design is subjected to loading that simulates typical service operation. The test article may be the entire airframe or a portion of it, and it should be a production article, conformed under 14 CFR 21.23, with every attribute that could affect crack initiation reproduced as closely as possible: material types and forms, dimensions, joining methods, coating and plating, faying-surface sealant, assembly processes and sequences.<\/p>\r\n\r\n<p>Boeing&rsquo;s own account of the 777-9 campaign, published in July 2026, fills in what that looks like in practice. Hydraulic actuators work the wings and the fuselage while the fuselage is pressurised, and the loads are sequenced so that the structure experiences a complete flight rather than an abstract cycle.<\/p>\r\n\r\n\r\n<div style=\"background:#f8f9fa;border-left:4px solid #5C91FF;padding:20px 22px;margin:18px 0 24px;font-size:16px;line-height:1.7;display:flex;gap:20px;align-items:flex-start\"><div><em>&ldquo;We will run this airplane through a complete ground-air-ground flight profile; so that&rsquo;s from the gate, to the gate and everything in between. The airframe thinks it&rsquo;s actually in flight.&rdquo;<\/em><div style=\"margin-top:10px;font-size:14px;color:#555\"><strong>Lee McNeil<\/strong> &mdash; Boeing 777-9 structures technical fellow<\/div><\/div><\/div>\r\n\r\n\r\n<p>The flights are not identical. Boeing rates them on an A to E scale: E flights, the vast majority, are short hops in benign weather, while A flights are the most intense long hauls, written to reproduce encounters such as thunderstorms over mountain passes. The mix reflects how often the aeroplane is likely to meet each condition in service, so the spectrum tests both the ordinary and the rare.<\/p>\r\n\r\n<p>The rig averages roughly 160 of these simulated flights every 24 hours. That is the whole trick: compressing decades of airline service into months of continuous machinery, around the clock, for years.<\/p>\r\n\r\n\r\n<div style=\"position:relative;padding-bottom:56.25%;height:0;overflow:hidden;margin:24px 0\"><iframe class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" src=\"https:\/\/www.youtube.com\/embed\/skw2TZAIlCI\" style=\"position:absolute;top:0;left:0;width:100%;height:100%;border:0\" allowfullscreen><\/iframe><\/div>\r\n\r\n\r\n<p>Boeing&rsquo;s own footage of the 777X fatigue campaign, showing the rig working through its cycle.<\/p>\r\n\r\n<h2 style=\"padding-top:22px\">Not the same rig as the one that breaks wings<\/h2>\r\n\r\n<p>It is worth being precise about the difference, because the two tests get confused constantly and the confusion flatters the wrong one. The static test is governed by the strength requirements of Part 25 subpart C. A factor of safety of 1.5 is applied to limit load under 14 CFR 25.303, and 14 CFR 25.305(b) requires the structure to support ultimate loads without failure for at least three seconds. One application, minutes of work, and a result that is either pass or a very loud fail. We have <a href=\"https:\/\/migflug.com\/afterburner\/ultimate-load-test-static-test-wing-limit-load-boeing-airbus\/\">written about that test before<\/a>.<\/p>\r\n\r\n\r\n<figure class=\"wp-block-image size-large\" style=\"margin:0 0 24px;width:100%\"><img decoding=\"async\" class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" width=\"1024\" src=\"https:\/\/migflug.com\/afterburner\/wp-content\/uploads\/sites\/4\/2026\/11\/static-test-vs-full-scale-fatigue-test-comparison.png\" alt=\"Comparison of the static ultimate load test and the full-scale fatigue test\" style=\"width:100%;height:auto;max-width:100%;display:block\"><figcaption style=\"font-size:13px;color:#777;text-align:center;margin-top:6px;font-style:italic\">The two rigs ask different questions, and only one of them sets the aircraft&rsquo;s service life. Diagram: Afterburner<\/figcaption><\/figure>\r\n\r\n\r\n<p>The fatigue rig never approaches ultimate load. It spends its life in the ordinary range, which is exactly the point, because that is where real aeroplanes live. Nothing dramatic happens for months at a time, and that is the result.<\/p>\r\n\r\n\r\n<div style=\"position:relative;padding-bottom:56.25%;height:0;overflow:hidden;margin:24px 0\"><iframe class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" src=\"https:\/\/www.youtube.com\/embed\/K2QoanZq2jE\" style=\"position:absolute;top:0;left:0;width:100%;height:100%;border:0\" allowfullscreen><\/iframe><\/div>\r\n\r\n\r\n<p>For contrast, the other kind of test: a 777 wing taken to 154 per cent of design limit load, with roughly 24 feet of tip deflection before it lets go. Twenty seconds of footage, and a completely different question from the one the fatigue rig is asking.<\/p>\r\n\r\n<h2 style=\"padding-top:22px\">The teardown is where the answer comes from<\/h2>\r\n\r\n<p>Running the cycles is only half of it. AC 25.571-1D sets out the sequence for evaluating structure susceptible to widespread fatigue damage, and the demonstration typically entails full-scale fatigue testing followed by teardown inspections and a quantitative evaluation of any finding, or residual-strength testing, or both.<\/p>\r\n\r\n<p>A teardown inspection, in the AC&rsquo;s own definition, is the process of disassembling structure and using destructive inspection techniques, or visual methods such as a magnifying glass and dye penetrant, or non-destructive ones such as eddy current and ultrasound, to identify the extent of damage caused by fatigue, corrosion and accidental damage. In other words, the test article is cut apart, hole by hole, so that cracks too small to find on a flying aeroplane can be measured on a dead one.<\/p>\r\n\r\n<p>The findings decide the number. Manufacturers typically set a design service goal, the period during which the structure is meant to stay reasonably free of significant cracking, and a recommended approach sets the candidate limit of validity equal to that design service goal. Whether the final LOV matches the candidate depends on how well the design objective was actually met, and on how much maintenance the manufacturer is willing to impose to preclude widespread fatigue damage up to that point.<\/p>\r\n\r\n\r\n<figure class=\"wp-block-image size-large\" style=\"margin:0 0 24px;width:100%\"><img decoding=\"async\" class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" width=\"1024\" src=\"https:\/\/migflug.com\/afterburner\/wp-content\/uploads\/sites\/4\/2026\/11\/boeing-777-9-fatigue-test-rig-structure.jpg\" alt=\"The steel structure of the Boeing 777-9 full-scale fatigue test rig\" style=\"width:100%;height:auto;max-width:100%;display:block\"><figcaption style=\"font-size:13px;color:#777;text-align:center;margin-top:6px;font-style:italic\">Hundreds of sensors watch the structure while hydraulic actuators work the wings and fuselage. Nothing visible happens for months, which is the intended result. Photo: Boeing \/ Patrick Rodwell<\/figcaption><\/figure>\r\n\r\n\r\n<p>Where a safe-life approach is used instead, under 14 CFR 25.571(c), variability is handled with a scatter factor, and AC 25.571-1D gives the base figures: BSF1 of 3.0, developed from the results of one representative test specimen, and BSF2 of 3.0 or greater where the criteria for using BSF1 cannot be met. A life-reduction factor of three is not timidity. It is an admission that one specimen cannot speak for a fleet.<\/p>\r\n\r\n<h2 style=\"padding-top:22px\">Certificated first, tested afterwards<\/h2>\r\n\r\n<p>Here is the part that surprises people. The regulation does not require the fatigue test to be finished before the aircraft is certificated. 14 CFR 25.571(b) says the type certificate may be issued prior to completion of full-scale fatigue testing, provided the Administrator has approved a plan for completing the required tests.<\/p>\r\n\r\n<p>That is not a loophole, it is arithmetic. A test that compresses three lifetimes of flying into a rig still takes years, and no manufacturer could hold a programme on the ground that long. So the aircraft enters service with an interim limitation in the airworthiness limitations section of its instructions for continued airworthiness, and the testing continues underneath the flying fleet. Boeing says every one of its aeroplanes since the 707 has been through this.<\/p>\r\n\r\n\r\n<div style=\"background:#f8f9fa;border-left:4px solid #3568e0;padding:20px 22px;margin:18px 0 24px;font-size:16px;line-height:1.7;display:flex;gap:20px;align-items:flex-start\"><div><em>&ldquo;All Boeing airplanes since the 707 have undergone full-scale fatigue testing, and we do this testing to ensure that we&rsquo;re meeting our rigorous safety and performance standards.&rdquo;<\/em><div style=\"margin-top:10px;font-size:14px;color:#555\"><strong>Tresha Lacaux<\/strong> &mdash; Boeing 777-9 vice president and chief project engineer<\/div><\/div><\/div>\r\n\r\n\r\n<p>It also explains why the fatigue rig does not stop when the aeroplane is certificated, and why it does not stop when the first lifetime is reached either. To operate an aircraft beyond its limit of validity, the full-scale fatigue-test evidence and the structural maintenance programme must be re-evaluated to see whether further modifications or replacements are needed. Extending an LOV typically means going back to the rig for more evidence. The structure in Everett is not finishing an old job. It is generating the permission slip for a fleet that does not exist yet.<\/p>\r\n\r\n\r\n<div style=\"position:relative;padding-bottom:56.25%;height:0;overflow:hidden;margin:24px 0\"><iframe class=\"skip-lazy\" data-no-lazy=\"1\" loading=\"eager\" src=\"https:\/\/www.youtube.com\/embed\/TH9k9fWaFrs\" style=\"position:absolute;top:0;left:0;width:100%;height:100%;border:0\" allowfullscreen><\/iframe><\/div>\r\n\r\n\r\n<p>The same process on the 787, filmed fifteen years ago, when the composite question was new and nobody could point at decades of service history to answer it.<\/p>\r\n\r\n<h2 style=\"padding-top:22px\">Why nobody films it<\/h2>\r\n\r\n<p>The static test gets the camera crews because it is a spectacle with an ending. The fatigue test has neither. It is a building full of hydraulic noise doing the same thing 160 times a day for years, watched by sensors, producing a number that eventually turns up in a maintenance manual as a line about inspection intervals.<\/p>\r\n\r\n<p>But the static test only proves the aeroplane is strong on the day it is built. The fatigue rig is the one that decides whether it is still safe after 30 years and 60,000 landings, and it is the only evidence the regulation will accept for that. The 777-9 article had passed 63,000 simulated flights when Boeing described the campaign in July 2026, with results matching expectations, and it has another 57,000 to go. Somewhere in Everett it is still at it, flying a route that does not exist, to an airport that was never built, for the benefit of passengers who have not bought their tickets yet.<\/p>\r\n\r\n<p><em>Sources: 14 CFR 25.303, 25.305, 25.307 and 25.571; FAA Advisory Circular 25.571-1D, Damage Tolerance and Fatigue Evaluation of Structure (13 January 2011), including Appendices 1 and 2; Boeing, Bending the 777-9: Inside fatigue testing for three lifetimes (July 2026).<\/em><\/p>\r\n\r\n<!-- mfsh:bottom -->\r\n\r\n<button type=\"button\" class=\"mfsh-trigger mfsh-bottom\" data-mfsh-placement=\"bottom\" aria-haspopup=\"dialog\"><svg><use href=\"#mfsh-i-share\"\/><\/svg>Share this story<\/button>\r\n\r\n<!-- \/mfsh:bottom -->\r\n\r\n\r\n<style>.mfq{margin:34px 0 8px}.mfq h2{font:26px\/1.3 \"Gilroy semiBold\",Helvetica,Arial,sans-serif;color:#0d1117;padding-top:22px;margin:0 0 6px}.mfq .qa details{border-top:1px solid #5C91FF;margin:0;padding:0}.mfq .qa details:last-of-type{border-bottom:1px solid #e2e7ee}.mfq .qa summary{cursor:pointer;list-style:none;display:flex;justify-content:space-between;align-items:center;gap:16px;padding:22px 26px;font:18px\/1.7 \"Gilroy semiBold\",Helvetica,Arial,sans-serif;color:#0d1117}.mfq .qa summary::-webkit-details-marker{display:none}.mfq .qa summary::after{content:\"+\";font:24px Helvetica,sans-serif;color:#3568e0;flex:0 0 auto}.mfq .qa details[open] summary::after{content:\"\\2013\"}.mfq .qa details:hover summary{color:#3568e0}.mfq .qa .a{font:16px\/1.7 \"Gilroy regular\",Helvetica,Arial,sans-serif;color:#454e5e;padding:0 26px 24px}.mfq .qa .a a{color:#3568e0}@media(max-width:680px){.mfq .qa summary{padding:18px 14px;font-size:17px}.mfq .qa .a{padding:0 14px 20px}}<\/style>\r\n\r\n\r\n<section class=\"mfq\"><h2>Frequently Asked Questions<\/h2><div class=\"qa\"><details open><summary>What is a full-scale fatigue test on an aircraft?<\/summary><div class=\"a\">It is a laboratory test in which a complete airframe, or a large portion of one, is subjected to repeated loading that simulates typical service operation. FAA Advisory Circular 25.571-1D specifies that the test article should be a production article conformed under 14 CFR 21.23, with materials, dimensions, joining methods, coatings, sealants and assembly processes reproduced as closely as possible.<\/div><\/details><details><summary>Why does an aircraft need a full-scale fatigue test if it already passed the static test?<\/summary><div class=\"a\">They answer different questions. The static test shows the structure can carry ultimate load, 1.5 times limit load under 14 CFR 25.303, without failing for at least three seconds. The fatigue test shows how many flights the structure can accumulate before widespread fatigue damage becomes likely. Only the fatigue test can establish the limit of validity.<\/div><\/details><details><summary>What is the limit of validity, or LOV, of an aircraft?<\/summary><div class=\"a\">AC 25.571-1D defines it as the period of time, in flight cycles or flight hours or both, up to which it has been demonstrated by test evidence, analysis and, where available, service experience and teardown inspections of high-time aircraft, that widespread fatigue damage will not occur in the airplane structure. 14 CFR 25.571(b) requires one to be established.<\/div><\/details><details><summary>What is widespread fatigue damage?<\/summary><div class=\"a\">It is simultaneous fatigue cracking at multiple locations in structure that shares the same details and stress levels, such as a long rivet line in a lap splice. The FAA treats it separately because, as AC 25.571-1D states, inspection methods cannot be relied on solely to ensure continued airworthiness indefinitely once this kind of damage becomes likely.<\/div><\/details><details><summary>How long does a full-scale fatigue test take?<\/summary><div class=\"a\">Years. Boeing says the 777-9 test article is being cycled to 120,000 complete simulated flights and that its rig averages roughly 160 simulated flights every 24 hours. The campaign had passed 63,000 cycles, more than one design lifetime, when Boeing published its account in July 2026.<\/div><\/details><details><summary>Can an aircraft be certified before its fatigue test is finished?<\/summary><div class=\"a\">Yes. 14 CFR 25.571(b) states that a type certificate may be issued before full-scale fatigue testing is complete, provided the Administrator has approved a plan for completing the required tests. In that case an interim limitation is carried in the airworthiness limitations section of the instructions for continued airworthiness until the testing is done and the LOV is approved.<\/div><\/details><details><summary>What is a teardown inspection?<\/summary><div class=\"a\">AC 25.571-1D defines it as disassembling structure and using destructive inspection techniques, or visual methods such as a magnifying glass and dye penetrant, or non-destructive methods such as eddy current and ultrasound, to identify the extent of damage caused by fatigue, corrosion and accidental damage. It is how a fatigue test article is read after the cycling stops.<\/div><\/details><details><summary>What is a scatter factor in fatigue testing?<\/summary><div class=\"a\">A life-reduction factor applied when interpreting fatigue analysis and test results, to account for variability. For safe-life determination under 14 CFR 25.571(c), AC 25.571-1D gives base scatter factors of BSF1 equal to 3.0, developed from one representative test specimen, and BSF2 of 3.0 or greater where the criteria for using BSF1 cannot be met.<\/div><\/details><\/div><\/section>\r\n\r\n\r\n\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"What is a full-scale fatigue test on an aircraft?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"It is a laboratory test in which a complete airframe, or a large portion of one, is subjected to repeated loading that simulates typical service operation. 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Only the fatigue test can establish the limit of validity.\"}},{\"@type\":\"Question\",\"name\":\"What is the limit of validity, or LOV, of an aircraft?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"AC 25.571-1D defines it as the period of time, in flight cycles or flight hours or both, up to which it has been demonstrated by test evidence, analysis and, where available, service experience and teardown inspections of high-time aircraft, that widespread fatigue damage will not occur in the airplane structure. 14 CFR 25.571(b) requires one to be established.\"}},{\"@type\":\"Question\",\"name\":\"What is widespread fatigue damage?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"It is simultaneous fatigue cracking at multiple locations in structure that shares the same details and stress levels, such as a long rivet line in a lap splice. 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For safe-life determination under 14 CFR 25.571(c), AC 25.571-1D gives base scatter factors of BSF1 equal to 3.0, developed from one representative test specimen, and BSF2 of 3.0 or greater where the criteria for using BSF1 cannot be met.\"}}]}<\/script><div style=\"background:#f0f4ff;border-left:4px solid #5C91FF;padding:16px 20px;margin:32px 0 8px\"><p style=\"margin:0 0 8px;font-weight:600;color:#333\">Related Posts<\/p><p style=\"margin:4px 0\"><a href=\"https:\/\/migflug.com\/afterburner\/ultimate-load-test-static-test-wing-limit-load-boeing-airbus\/\">Ultimate Load Test: Why Boeing and Airbus Bend Wings to Breaking<\/a><\/p><p style=\"margin:4px 0\"><a href=\"https:\/\/migflug.com\/afterburner\/safe-life-fail-safe-design-damage-tolerance-f-111-comet-25-571\/\">Safe-Life vs Fail-Safe Design: What the Comet and F-111 Taught<\/a><\/p><p style=\"margin:4px 0\"><a href=\"https:\/\/migflug.com\/afterburner\/how-long-does-an-airliner-last-flight-hours-cycles-metal-fatigue\/\">How Long Does an Airliner Last? Flight Hours, Cycles and Fatigue<\/a><\/p><p style=\"margin:4px 0\"><a href=\"https:\/\/migflug.com\/afterburner\/de-havilland-comet-metal-fatigue-square-windows-investigation-1954\/\">The de Havilland Comet: The Beautiful Jet That Taught Us How Aircraft Break<\/a><\/p><\/div>\r\n","protected":false},"excerpt":{"rendered":"<p>Share this story Outside a building in Everett, Washington, inside a steel cage painted a startling shade of blue, a Boeing 777-9 is flying. It will never leave the ground. It has no engines, no paint and no passengers. It is the fourth 777-9 Boeing built, and it was rolled out of the factory and [&hellip;]<\/p>\n","protected":false},"author":23,"featured_media":32147521,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"editor_notices":[],"footnotes":""},"categories":[665],"tags":[],"class_list":["post-32148289","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-aviation-world"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Full-Scale Fatigue Test: The Boeing 777-9 Rig | MiGFlug<\/title>\n<meta name=\"description\" content=\"Inside the full-scale fatigue test: how the Boeing 777-9 rig flies 160 times a day, and why it, not the static test, sets an airliner&rsquo;s life.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" 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