{ "standard": "FactUnion Standard v1", "checkedAt": "2026-10-18T22:09:25.351Z", "title": "The Twin That Was Too Strong", "date": "2026-10-18", "facts": [ { "n": 1, "claim": "Paragraph 77 of the Cohen report says it is probable the cabin disruption on G-ALYP began near the starboard aft corner of the rear ADF window, at the edge of a countersunk bolt hole where fatigue was identified.", "sources": [ { "url": "https://www.key.aero/forum/historic-aviation/64571-comet-metal-fatigue", "title": "Comet metal fatigue" } ], "verdict": "verified", "note": "Kept on a lower-weight source (key.aero); nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 2, "claim": "The Court report records that three cracks were found in the reinforcing plates of the ADF windows and were approved by the Chief Inspector and Design Department, with the crack ends drilled with a 1/16 in drill (para 137).", "sources": [ { "url": "https://www.key.aero/forum/historic-aviation/64571-comet-metal-fatigue", "title": "Comet metal fatigue" } ], "verdict": "verified", "note": "Kept on a lower-weight source (key.aero); nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 3, "claim": "In the Farnborough water tank, G-ALYU failed after 1,221 real flights plus 1,836 simulated cycles (3,057 in all), with the fatigue crack starting at a rivet hole near the forward port escape hatch.", "sources": [ { "url": "https://www.rafmuseum.org.uk/research/archive-exhibitions/comet-the-worlds-first-jet-airliner/comet-failure/", "title": "Comet - The World's First Jet Airliner | Comet - The World's First Jet Airliner | Archive Exhibitions | Exhibitions & Displays | Research | RAF Museum" }, { "url": "https://engineerine.com/de-havilland-comet-worlds-first/", "title": "Why Investigators Put a Comet Jet Airliner in a Water Tank" }, { "url": "https://github.com/Ehsan-Roohi/Aerospace-Structures/blob/main/COMET_WINDOWS_AND_FATIGUE.md", "title": "Aerospace-Structures/COMET_WINDOWS_AND_FATIGUE.md at main · Ehsan-Roohi/Aerospace-Structures · GitHub" } ], "verdict": "verified", "note": "Kept on a lower-weight source (RAF Museum); nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 4, "claim": "BCAR of the era required a design pressure of 2P and a proof test of 1.33P, while de Havilland designed the Comet 1 cabin to 2.5P and proof-tested to 2P (16.5 psi).", "sources": [ { "url": "https://www.dh-aircraft.co.uk/aircraft/dh106/comet1/inquiry/", "title": "Comet 1 Inquiry" }, { "url": "https://www.faa.gov/lessons_learned/transport_airplane/accidents/G-ALYV", "title": "De Havilland DH-106 Comet 1 | Federal Aviation Administration" }, { "url": "https://www.imeche.org/news/news-article/remembering-the-comet", "title": "Remembering the Comet" } ], "verdict": "verified", "quote": false, "usedInEpisode": true }, { "n": 5, "claim": "Before its fatigue test, de Havilland's forward-fuselage test section had taken 30 applications of pressure between 1P and 2P and about 2,000 applications up to 'rather over P', and the same section was then fatigue-cycled up to P.", "sources": [ { "url": "https://www.globalsecurity.org/military/world/europe/comet-accidents.htm", "title": "DeHavilland Comet" }, { "url": "https://www.faa.gov/lessons_learned/transport_airplane/accidents/G-ALYV", "title": "De Havilland DH-106 Comet 1 | Federal Aviation Administration" }, { "url": "https://aerossurance.com/safety-management/comet-misconceptions/", "title": "Common Comet Misconceptions and Collaborative Contribution to Safety" } ], "verdict": "verified", "quote": false, "usedInEpisode": true }, { "n": 6, "claim": "De Havilland's fatigue-tested prototype fuselage failed at 16,000 pressurization cycles.", "sources": [ { "url": "https://www.faa.gov/lessons_learned/transport_airplane/accidents/G-ALYV", "title": "De Havilland DH-106 Comet 1 | Federal Aviation Administration" }, { "url": "https://aerossurance.com/safety-management/comet-misconceptions/", "title": "Common Comet Misconceptions and Collaborative Contribution to Safety" }, { "url": "https://www.linkedin.com/pulse/week-focus-comet-passed-its-fatigue-test-ross-kudwitt-gftxc", "title": "The de Havilland Comet, the world's first jet airliner, had a test fuselage that survived 16,000 pressurization cycles before it cracked. In 1954 two Comets in airline service broke apart in the air, " } ], "verdict": "corrected", "note": "Original wrongly said 18,000 cycles and survived. Evidence says the prototype fuselage failed at 16,000 cycles. The 1953 date and forward-section detail are not stated.", "quote": false, "usedInEpisode": true }, { "n": 7, "claim": "Production Comet 1s, including G-ALYU, did not receive the 2P proof test, so they lacked the cold-working that inadvertently improved the test specimen's fatigue life.", "sources": [ { "url": "https://www.linkedin.com/pulse/week-focus-comet-passed-its-fatigue-test-ross-kudwitt-gftxc", "title": "The de Havilland Comet, the world's first jet airliner, had a test fuselage that survived 16,000 pressurization cycles before it cracked. In 1954 two Comets in airline service broke apart in the air, " }, { "url": "https://www.globalsecurity.org/military/world/europe/comet-accidents.htm", "title": "DeHavilland Comet" }, { "url": "https://www.linkedin.com/pulse/airliner-over-engineered-wrong-kind-failure-trang-nguyen-am1wc", "title": "On the morning of January 10, 1954, BOAC Comet G-ALYP climbed out of Rome's Ciampino Airport on the final leg of a long-haul route from Singapore to London. Thirty-five people were on board." } ], "verdict": "verified", "note": "Kept on a lower-weight source (LinkedIn); nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 8, "claim": "De Havilland estimated the average stress at window corners at about 28,000 psi.", "sources": [ { "url": "https://www.key.aero/forum/historic-aviation/64571-comet-metal-fatigue", "title": "Comet metal fatigue" }, { "url": "https://www.youtube.com/watch?v=q6n77wESQko", "title": "Comet square windows: what the court found - YouTube" }, { "url": "https://biggo.com/news/202508021322_Comet_Museum_Restoration_Sparks_Aviation_Discussion", "title": "De Havilland Comet Museum Restoration Sparks Discussion About Aviation's First Jet Airliner Tragedy" } ], "verdict": "verified", "quote": false, "usedInEpisode": true }, { "n": 9, "claim": "The Comet 1 cabin skin was 22-gauge (0.71 mm), thickened to 20-gauge (0.91 mm) around the windows.", "sources": [ { "url": "https://simpleflying.com/boeing-747-pioneer-quadjet-travel-jet-did/", "title": "The Boeing 747 Actually Didn’t Pioneer Quadjet Travel: Here’s The Jet That Did" }, { "url": "https://www.airliners.net/forum/viewtopic.php?t=1382979", "title": "De Havilland Comet Dimensions for FEA" } ], "verdict": "corrected", "note": "Source corrected: the page first cited was read and is about something else; the sources listed state this.", "quote": false, "usedInEpisode": true }, { "n": 10, "claim": "The RAE report R&M 3248 describes the Comet I window apertures as reinforced by peripheral members bonded with Redux adhesive and also secured with countersunk-head rivets at the corners.", "sources": [ { "url": "https://anyflip.com/kmvx/kpvf/basic", "title": "Behaviour of Skin Fatigue Cracks at the Corners of Windows ... - Flip eBook Pages 1-49 | AnyFlip" } ], "verdict": "verified", "note": "Kept on a lower-weight source (AnyFlip); nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 11, "claim": "The Comet 1's passenger windows were near-square, with corners that were rounded, but not as much as on modern square windows.", "sources": [ { "url": "https://aviation.stackexchange.com/questions/59627/why-weren-t-the-comet-s-overhead-adf-windows-roundified-along-with-its-passenger", "title": "Why weren’t the Comet’s overhead ADF windows roundified along with its passenger windows?" }, { "url": "https://www.linkedin.com/pulse/airliner-over-engineered-wrong-kind-failure-trang-nguyen-am1wc", "title": "On the morning of January 10, 1954, BOAC Comet G-ALYP climbed out of Rome's Ciampino Airport on the final leg of a long-haul route from Singapore to London. Thirty-five people were on board." } ], "verdict": "corrected", "note": "Original wrongly said angled corners meant to spread stress; sources say near-square windows with lightly softened, rounded corners, with no stated stress-spreading purpose. Kept on a lower-weight source; nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 12, "claim": "Operation Elba Isle (20 January to 11 April 1954) used the RFA Sea Salvor and several Royal Navy ships to recover wreckage of the BOAC Comet G-ALYP, which crashed into the sea off Elba.", "sources": [ { "url": "https://historicalrfa.uk/1954-operation-elba-isle/", "title": "1954 - Operation Elba Isle - Historical RFA" } ], "verdict": "corrected", "note": "Removed unsupported HMS Wrangler headquarters role, Hayward as commander, and 450-600 ft depth; dates, Sea Salvor and Elba crash are supported. Kept on a lower-weight source; nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 13, "claim": "An Admiralty Research Laboratory team led by George MacNeice developed underwater TV cameras that were used to help locate and salvage wreckage in deep water.", "sources": [ { "url": "https://alchetron.com/BOAC-Flight-781", "title": "BOAC Flight 781 - Alchetron, The Free Social Encyclopedia" }, { "url": "https://en.wikipedia.org/wiki/BOAC_Flight_781", "title": "BOAC Flight 781" }, { "url": "https://everything.explained.today/BOAC_Flight_781/", "title": "BOAC Flight 781 explained" } ], "verdict": "corrected", "note": "The evidence supports the TV cameras and deep-water salvage only. The grab, observation chamber, and divers-unable-to-reach claims are not stated, so they were dropped.", "quote": false, "usedInEpisode": true }, { "n": 14, "claim": "At Farnborough, RAE investigators mounted the recovered fragments on a frame to rebuild the fuselage like a jigsaw.", "sources": [ { "url": "https://admiralcloudberg.medium.com/neither-money-nor-manpower-the-story-of-the-de-havilland-comet-and-the-crash-of-boac-flight-781-36db2a3435ce", "title": "Neither Money Nor Manpower: The story of the de Havilland Comet and the crash of BOAC flight 781 | by Admiral Cloudberg | Medium" }, { "url": "http://aircraftinvestigation.info/airplanes/DH_Comet_I_accident_report.html", "title": "De Havilland Comet I accident report" } ], "verdict": "verified", "note": "Kept on a lower-weight source (Medium); nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 15, "claim": "South African Airways Flight 201 (G-ALYY), a charter operated for BOAC, broke up near Naples on 8 April 1954 and killed all 21 aboard, 14 passengers and 7 crew.", "sources": [ { "url": "https://en.wikipedia.org/wiki/South_African_Airways_Flight_201", "title": "South African Airways Flight 201" }, { "url": "https://www.faa.gov/lessons_learned/transport_airplane/accidents/G-ALYV", "title": "De Havilland DH-106 Comet 1 | Federal Aviation Administration" }, { "url": "https://everything.explained.today/South_African_Airways_Flight_201/", "title": "South African Airways Flight 201 Explained" } ], "verdict": "verified", "quote": false, "usedInEpisode": true }, { "n": 16, "claim": "After the Naples accident, BOAC suspended all Comet flights and the aircraft's certificate of airworthiness was withdrawn.", "sources": [ { "url": "https://www.faa.gov/lessons_learned/transport_airplane/accidents/G-ALYV", "title": "De Havilland DH-106 Comet 1 | Federal Aviation Administration" }, { "url": "https://www.linkedin.com/pulse/week-focus-comet-passed-its-fatigue-test-ross-kudwitt-gftxc", "title": "The de Havilland Comet, the world's first jet airliner, had a test fuselage that survived 16,000 pressurization cycles before it cracked. In 1954 two Comets in airline service broke apart in the air, " }, { "url": "https://www.globalsecurity.org/military/world/europe//comet-accidents.htm", "title": "DeHavilland Comet" } ], "verdict": "verified", "quote": false, "usedInEpisode": true }, { "n": 17, "claim": "Attorney General Sir Lionel Heald told the inquiry that the fatigue had developed near the radio direction-finding aerial window in the cabin roof, and that up to 70 percent of ultimate stress was concentrated at the window corners.", "sources": [ { "url": "http://news.bbc.co.uk/onthisday/low/dates/stories/october/19/newsid_3112000/3112466.stm", "title": "'Metal fatigue' caused Comet crashes" }, { "url": "https://cdnedge.bbc.co.uk/onthisday/low/dates/stories/october/19/newsid_3112000/3112466.stm", "title": "BBC ON THIS DAY | 19 | 1954: 'Metal fatigue' caused Comet crashes" }, { "url": "http://news.bbc.co.uk/onthisday/hi/dates/stories/october/19/newsid_3112000/3112466.stm", "title": "'Metal fatigue' caused Comet crashes" } ], "verdict": "corrected", "note": "Source corrected: the page first cited was read and is about something else; the sources listed state this.", "quote": false, "usedInEpisode": true }, { "n": 18, "claim": "The Science Museum Group holds a section of the upper fuselage of G-ALYP showing the fatigue cracks around its ADF openings (object co202453).", "sources": [ { "url": "https://www.linkedin.com/pulse/week-focus-comet-passed-its-fatigue-test-ross-kudwitt-gftxc", "title": "The de Havilland Comet, the world's first jet airliner, had a test fuselage that survived 16,000 pressurization cycles before it cracked. In 1954 two Comets in airline service broke apart in the air, " } ], "verdict": "verified", "note": "Kept on a lower-weight source (LinkedIn); nothing we found says otherwise.", "quote": false, "usedInEpisode": true }, { "n": 19, "claim": "The fuselage of the last surviving short-fuselage Comet 1XB, G-APAS, left the RAF Museum Midlands at Cosford on 9 September for the South Wales Aviation Museum at St Athan.", "sources": [ { "url": "https://vintageaviationnews.com/aviation-museum-news/last-surviving-short-fuselage-de-havilland-comet-1xb-transferred-from-raf-museum-midlands-to-south-wales-aviation-museum.html", "title": "Last Surviving Short-Fuselage de Havilland Comet 1XB Transferred from RAF Museum Midlands to South Wales Aviation Museum" }, { "url": "https://www.key.aero/article/comet-1-leaves-cosford", "title": "Comet 1 leaves Cosford" } ], "verdict": "corrected", "note": "Wrongly claimed arrival and corrosion-related wing loss; evidence only shows the fuselage left Cosford on 9 September, bound for St Athan.", "quote": false, "usedInEpisode": true }, { "n": 20, "claim": "The Comet 1A fuselage F-BGNX at the de Havilland Aircraft Museum is described by the museum as the only surviving Comet fuselage with the original square-shaped windows.", "sources": [ { "url": "https://www.bbc.com/news/uk-england-beds-bucks-herts-50585312", "title": "Last square-windowed Comet moved to new de Havilland Museum hangar" }, { "url": "https://www.airhistory.net/photo/584790/F-BGNX", "title": "De Havilland D.H. 106 Comet 1A" }, { "url": "https://abpic.co.uk/pictures/view/1681623", "title": "De Havilland DH.106 Comet 1A, F-BGNX / 06020, de Havilland Aircraft Museum (de Havilland Aircraft Heritage Centre) :" } ], "verdict": "corrected", "note": "Source corrected: the page first cited was read and is about something else; the sources listed state this.", "quote": false, "usedInEpisode": true } ], "removed": [ { "claim": "Paragraph 78 says a manufacturing crack of about 0.2 in at the forward port corner of the same ADF window was dealt with under the de Havilland Concession procedure by drilling small holes at its ends, and that no witness could identify fatigue at that spot.", "reason": "Couldn't be checked: a key record would not open." }, { "claim": "An ARC paper on pre-loading reports that tensile pre-loading creates compressive residual stress at stress concentrations, raising fatigue life by anything from moderate amounts to about a hundredfold, and warns that proof-testing a specimen before a fatigue test can give an inflated estimate of service life.", "reason": "We could not find a public record about this either way." }, { "claim": "The same ARC pre-loading paper cites earlier studies, including work on Meteor tailplanes and by Johnstone and Payne, showing the effect was known in the fatigue literature.", "reason": "We could not find a public record about this either way." }, { "claim": "RAE strain gauges on G-ALYU found peak local stresses of about 45,700 psi (315 MPa) at window corners, roughly 70% of the ultimate tensile strength of the DTD 546 alloy (about 450 MPa).", "reason": "We could not find a public record about this either way." }, { "claim": "Scholz's 2019 review, discussing Paul Withey's work, says the failed bolt hole on G-ALYP had a defect in its chamfer.", "reason": "We could not find a public record about this either way." }, { "claim": "A former RAE engineer writing in 2012 accepted punch-riveting as a factor in starting cracks, said it was standard practice for the era, and called the 'carpenters versus metalworkers' story 'scuttlebutt'.", "reason": "We could not find a public record about this either way." }, { "claim": "BOAC Flight 781 (G-ALYP) killed all 35 aboard, 29 passengers and 6 crew, on 10 January 1954; among them were the journalist Chester Wilmot and Captain Alan Gibson.", "reason": "Only lower-weight sources state this: Alchetron, The Free Social Encyclopedia and 1 more." }, { "claim": "The Court of Inquiry under Lord Cohen sat from 19 October to 24 November 1954 and cleared de Havilland, finding it had applied the scientific precautions known at the time.", "reason": "Sources only partly back this: The New York Times." }, { "claim": "The fatigue engineer Jaap Schijve points out that the beneficial effect of the earlier proof test on the Comet fatigue specimen was overlooked at the time.", "reason": "We could not find a public record about this either way." } ], "audioCheck": { "lines": 133, "matched": 133 }, "corrections": [], "verify": { "method": "1.2", "llmMode": "testing", "models": { "summary": "claude-haiku-5-5", "extract": "claude-haiku-5-5", "consolidate": "claude-haiku-5-5", "query": "claude-haiku-5-5", "read": "claude-haiku-5-5", "read_second": "claude-sonnet-5-5", "compare": "claude-haiku-5-5", "classify": "claude-haiku-5-5", "explain": "claude-haiku-5-5", "undash": "claude-haiku-5-5", "correct": "claude-haiku-5-5" }, "preScript": { "jobId": "job_37NDC03QYKS0XXYJ9814", "checkedAt": "2026-10-18T22:09:25.351Z", "counts": { "verified": 12, "corrected": 8, "removed": 9 } }, "episode": { "jobId": "job_B4D257Y8V2K7M9AJ3Y6C", "checkRef": "chk_XSTD1GMNVXE0Y52DKW6X", "trustPageUrl": null, "checkedAt": "2026-10-19T03:35:58.447Z", "score": null, "outcome": "not_rated", "counts": { "verified": 38, "not_verified": 1, "questionable": 36, "unable_to_determine": 22 }, "stability": { "spread": 6, "unstableClaims": 8, "pass": false }, "notVerified": [ { "k": 23, "claim": "The Comet windows had rounded corners, though less rounded than on modern airliner windows.", "reasonText": "Federal Aviation Administration states something different: \"The Comet's unique squarish window corners resulted in especially high stress levels.\"." } ], "questionable": [ { "k": 2, "claim": "Underwater cameras used in the Elba search were built by a team at the Admiralty Research Laboratory led by George McNeese.", "reasonText": "Sources only partly back this: Federal Aviation Administration." }, { "k": 3, "claim": "Operation Elba Isle, the search in the sea off Elba, ran from January 20 to April 11.", "reasonText": "Only lower-weight sources state this: Historical RFA and 1 more." }, { "k": 8, "claim": "Investigators hung the recovered Comet pieces on a frame, one by one, to rebuild the airplane.", "reasonText": "Only one source states this: radiohangar.com." }, { "k": 9, "claim": "One of the recovered Comet pieces is held in the Science Museum Group collection.", "reasonText": "Only lower-weight sources state this: LinkedIn and 1 more." }, { "k": 12, "claim": "Fatigue cracks run out from the corners of the small radio aerial window in the recovered cabin roof section.", "reasonText": "Sources only partly back this: Federal Aviation Administration." }, { "k": 14, "claim": "On every Comet flight the cabin was pumped up with air during the climb and let back down during the descent.", "reasonText": "Only one source states this: mentourpilot.com." }, { "k": 15, "claim": "On the Comet, the cracks grew from tiny holes at the corners of openings in the cabin.", "reasonText": "Only lower-weight sources state this: AnyFlip and 2 more." }, { "k": 17, "claim": "The Comet fuselage F-GNXU, described as a Comet 1A, is at the de Havilland Aircraft Museum.", "reasonText": "Sources only partly back this: BBC." }, { "k": 18, "claim": "The de Havilland Aircraft Museum describes F-GNXU as the only surviving Comet fuselage with the original square-shaped windows.", "reasonText": "The fact holds, but the named source does not say it." }, { "k": 24, "claim": "Investigators traced the start of the two Comet failures to a spot beside the roof radio aerial window and a spot beside an escape hatch, not to a passenger window.", "reasonText": "Only lower-weight sources state this: Blogger and 1 more." }, { "k": 27, "claim": "Linkly says a first version of an app usually takes under half an hour to build.", "reasonText": "Only one source states this: lynqly.com." }, { "k": 33, "claim": "Planning with Linkly is free and requires no sign up.", "reasonText": "Sources only partly back this: linkly.li." }, { "k": 36, "claim": "The document read from is the Court of Inquiry report into the Comet accidents.", "reasonText": "Only one source states this: docslib.org." }, { "k": 37, "claim": "In paragraph 77 the Court of Inquiry found it probable that the cabin disruption of G-ALYP began at a countersunk bolt hole at the edge of the aft starboard corner of the rear ADF window, where fatigue was identified.", "reasonText": "Only one source states this: key.aero." }, { "k": 40, "claim": "Sir Lionel Heald told the Comet inquiry that up to 70% of ultimate stress was concentrated at the window corners.", "reasonText": "The fact holds, but the named source does not say it." }, { "k": 45, "claim": "The test airframe reached 3,057 cycles in total before it split.", "reasonText": "Only lower-weight sources state this: Wikipedia and 2 more." }, { "k": 46, "claim": "The fatigue crack in the test airframe started at a rivet hole near the forward port escape hatch.", "reasonText": "Only lower-weight sources state this: RAF Museum and 1 more." }, { "k": 47, "claim": "Sources disagree on the total test cycle count, giving 3,057 in some places and 3,060 in others.", "reasonText": "Only one source states this: engineerine.com." }, { "k": 48, "claim": "The Comet 1 cabin skin was 22 gauge, about 0.7 millimetres thick.", "reasonText": "Only lower-weight sources state this: AnyFlip and 2 more." }, { "k": 50, "claim": "The Comet window corners were built with countersunk fastener holes cut right next to the corners.", "reasonText": "Only one source states this: AnyFlip." }, { "k": 51, "claim": "The Royal Aircraft Establishment report R and M 3248 describes the Comet window openings as reinforced with strips bonded on with the adhesive Redux.", "reasonText": "Only lower-weight sources state this: AnyFlip and 1 more." }, { "k": 52, "claim": "The Royal Aircraft Establishment report R and M 3248 says the Comet window openings were also secured at the corners with countersunk head rivets.", "reasonText": "Only one source states this: AnyFlip." }, { "k": 53, "claim": "De Havilland estimated the average stress at the Comet window corners at about 28,000 psi.", "reasonText": "Only one source states this: key.aero." }, { "k": 55, "claim": "The cracks in the ADF window reinforcing plates were approved by the chief inspector and the design department.", "reasonText": "Only one source states this: key.aero." }, { "k": 56, "claim": "The ends of the cracks in the ADF window reinforcing plates were drilled with a one sixteenth inch drill.", "reasonText": "Only one source states this: key.aero." }, { "k": 59, "claim": "The Court of Inquiry said the ADF window was the window that failed first.", "reasonText": "Sources only partly back this: BBC." }, { "k": 63, "claim": "De Havilland proof tested the Comet 1 cabin to two times p, 16.5 psi.", "reasonText": "Only lower-weight sources state this: simpleflying.com and 1 more." }, { "k": 65, "claim": "De Havilland built a fuselage front test section before the Comet carried any paying passengers.", "reasonText": "Sources only partly back this: Federal Aviation Administration." }, { "k": 71, "claim": "Some sources say the fuselage test section lasted 18,000 cycles before it cracked.", "reasonText": "Only lower-weight sources state this: shippai.org and 1 more." }, { "k": 74, "claim": "The corners and holes in the production Comets were very likely not braced the way the test sections were.", "reasonText": "Sources only partly back this: Federal Aviation Administration." }, { "k": 76, "claim": "The sources do not fully agree on what proof load the production Comet aircraft received.", "reasonText": "Only one source states this: globalsecurity.org." }, { "k": 78, "claim": "The de Havilland test section was strengthened in the kinds of spots where the cracks later started.", "reasonText": "Only one source states this: LinkedIn." }, { "k": 79, "claim": "Nobody toughened the fastener-hole corners of the production Comet airframes beforehand.", "reasonText": "Sources only partly back this: Federal Aviation Administration." }, { "k": 87, "claim": "The starting point of the Naples Comet G-ALYY failure is unknown and is an inference, because too little of its wreckage could be examined.", "reasonText": "Sources only partly back this: Federal Aviation Administration." }, { "k": 92, "claim": "The recovered piece of Comet cabin roof is a curved sheet of thin metal.", "reasonText": "Sources only partly back this: Federal Aviation Administration." }, { "k": 93, "claim": "The recovered roof section has a bolt hole at one corner where the fatigue crack began.", "reasonText": "Only one source states this: key.aero." } ] } } }