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14th November 2018, 10:23 |
#191
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Mania Member
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Sementara itu, usaha-usaha sedang dilakukan untuk mengubah software kontrol ataupun perubahan desain dari Boeing 737 Max 8...
Boeing, US regulator weigh software fix on 737 Max after crash Boeing Co and US aviation regulators are weighing whether to issue a software fix to the 737 Max, the aircraft type involved in a recent crash in Indonesia to ensure that the plane won't dive aggressively without pilot commands. Boeing and the Federal Aviation Administration "continue to evaluate the need for software and or other design changes to the aircraft", the agency said in a statement on Tuesday (Nov 13). A safety feature added to the updated 737 Max, which was designed to prevent pilots from losing control, has been implicated by Indonesian investigators in a Lion Air jet's sudden dive into the Java sea after taking off from Jakarta on Oct 29. The pilots were attempting to deal with several malfunctions when the crash occurred, the investigators said. All 189 people aboard died in the high-velocity impact. The FAA and the manufacturer are also evaluating the need for other upgrades, "including operating procedures and training," the FAA said in the statement. The FAA on Nov 7 issued an emergency airworthiness directive ordering US airlines to incorporate information about the feature in their pilot manuals. Two US pilot unions at carriers flying the Max said on Monday that the company didn't adequately spell out how the new system worked in training and manuals. - https://www.straitstimes.com/world/u...ax-after-crash |
14th November 2018, 10:32 |
#192
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Groupie Member
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Quote:
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15th November 2018, 11:53 |
#193
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Mania Member
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November 14, 2018
Boeing's automatic trim for the 737 MAX was not disclosed to the Pilots The automatic trim Boeing introduced on the 737 MAX, called MCAS, was news to us last week. Graver, it was news to the Pilots flying the MAX since 18 months as well. Boeing and its oversight, the FAA, decided the Airlines and their Pilots had no need to know. The Lion Air accident can prove otherwise. Lion Air PK-LQP The background to Boeing's 737 MAX automatic trim The automatic trim we described last week has a name, MCAS, or Maneuvering Characteristics Automation System. It's unique to the MAX because the 737 MAX no longer has the docile pitch characteristics of the 737NG at high Angles Of Attack (AOA). This is caused by the larger engine nacelles covering the higher bypass LEAP-1B engines. The nacelles for the MAX are larger and placed higher and further forward of the wing, Figure 1. Figure 1. Boeing 737NG (left) and MAX (right) nacelles compared. Source: Boeing 737 MAX brochure. By placing the nacelle further forward of the wing, it could be placed higher. Combined with a higher nose landing gear, which raises the nacelle further, the same ground clearance could be achieved for the nacelle as for the 737NG. The drawback of a larger nacelle, placed further forward, is it destabilizes the aircraft in pitch. All objects on an aircraft placed ahead of the Center of Gravity (the line in Figure 2, around which the aircraft moves in pitch) will contribute to destabilize the aircraft in pitch. Figure 2. The 737-800 (yellow) overlaid on the 737 MAX 8 (purple), with the line denoting the CG in pitch. Source: Leeham Co. and 737 ACAP. The 737 is a classical flight control aircraft. It relies on a naturally stable base aircraft for its flight control design, augmented in selected areas. Once such area is the artificial yaw damping, present on virtually all larger aircraft (to stop passengers getting sick from the aircraft's natural tendency to Dutch Roll = Wagging its tail). Until the MAX, there was no need for artificial aids in pitch. Once the aircraft entered a stall, there were several actions described last week which assisted the pilot to exit the stall. But not in normal flight. The larger nacelles, called for by the higher bypass LEAP-1B engines, changed this. When flying at normal angles of attack (3 Degree at cruise and say 5-8 Degree in a turn) the destabilizing effect of the larger engines are not felt. The nacelles are designed to not generate lift in normal flight. It would generate unnecessary drag as the aspect ratio of an engine nacelle is lousy. The aircraft designer focuses the lift to the high aspect ratio wings. But if the pilot for whatever reason manoeuvres the aircraft hard, generating an angle of attack close to the stall angle of around 14 Degree, the previously neutral engine nacelle generates lift. A lift which is felt by the aircraft as a pitch up moment (as its ahead of the CG line), now stronger than on the 737NG. This destabilizes the MAX in pitch at higher Angles Of Attack (AOA). The most difficult situation is when the manoeuvre has a high pitch ratio. The aircraft's inertia can then provoke an over-swing into stall AOA. To counter the MAX's lower stability margins at high AOA, Boeing introduced MCAS. Dependent on AOA value and rate, altitude (air density) and Mach (changed flow conditions) the MCAS, which is a software loop in the Flight Control computer, initiates a nose down trim above a threshold AOA. It can be stopped by the Pilot counter-trimming on the Yoke or by him hitting the CUTOUT switches on the center pedestal. It's not stopped by the Pilot pulling the Yoke, which for normal trim from the autopilot or runaway manual trim triggers trim hold sensors. This would negate why MCAS was implemented, the Pilot pulling so hard on the Yoke that the aircraft is flying close to stall. It's probably this counterintuitive characteristic, which goes against what has been trained many times in the simulator for unwanted autopilot trim or manual trim runaway, which has confused the pilots of JT610. They learned that holding against the trim stopped the nose down, and then they could take action, like counter-trimming or outright CUTOUT the trim servo. But it didn't. After a 10 second trim to a 2.5 Degree nose down stabilizer position, the trimming started again despite the Pilots pulling against it. The faulty high AOA signal was still present. How should they know that pulling on the Yoke didn't stop the trim? It was described nowhere; neither in the aircraft's manual, the AFM, nor in the Pilot's manual, the FCOM. This has created strong reactions from airlines with the 737 MAX on the flight line and their Pilots. They have learned the NG and the MAX flies the same. They fly them interchangeably during the week. They do fly the same as long as no fault appears. Then there are differences, and the Pilots should have been informed about the differences. ======= || ======= - https://leehamnews.com/2018/11/14/bo...to-the-pilots/ |
15th November 2018, 12:14 |
#194
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Mania Member
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Which phase of flight is a crash most likely to occur?
Boeing released the following statistics for the worldwide Commercial Jet Fleet between 2005 -- 2014. Percentages of fatal accidents based on phase of flight: 13% Take-off 8% Climb 27% Cruise 17% Decent Initial Approach 38% Final Approach / Landing Therefore, statistically, the most dangerous phase of flight is landing. Kalau digabungkan, saat-saat yang paling berbahaya pada penerbangan adalah pada saat-saat persiapan mendarat dan pada saat pendaratan [55%]. Sebetulnya saat take-off juga kritis, karena proses take-off itu boleh dibilang sangat pendek dibandingkan dengan fase-fase lain, mungkin kurang dari 5% dari total waktu penerbangan, akan tetapi kecelakaan yang terjadi pada saat take-off ada di kisaran 13%. - https://www.news.com.au/travel/trave...6df73d5791c0fd |
15th November 2018, 23:17 |
#195
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Mania Member
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November 14, 2018
FAA evaluates a potential design flaw on Boeing's 737 MAX after Lion Air crash Analysts, including former Boeing flight controls experts, are concerned that a new automated flight control system on Boeing's 737 MAX may be flawed and that the way it changed the jet's handling could have sown confusion on the flight deck of Lion Air Flight JT610. The Federal Aviation Administration (FAA) said Wednesday it's evaluating whether to require Boeing to fix a possible flaw in its design of a new automated flight control system introduced for the 737 MAX jet. It's also looking into whether the technical data and training provided to pilots transitioning to the new jet model was adequate. Flight control experts believe that lack of information about the new system likely confused the pilots flying the Lion Air jet that crashed Oct. 29 in Indonesia, killing all 189 people on board. The air safety agency said Wednesday that "the FAA and Boeing continue to evaluate the need for software and/or other design changes to the aircraft, including operating procedures and training." The accident investigation has already established that false readings from a sensor that measures the plane's angle of attack (AOA) - the angle between the wing and the oncoming air flow - could have triggered a flight control system new on the MAX that relentlessly pushed the nose of the aircraft downward. FAA spokesman Greg Martin said "the angle of attack values used by several systems, including the air data, the fight controls, the stall warning, etcetera, the safety analysis for each of these systems are currently being reviewed." Flight control experts say the new system kicking in would have changed the feel of the plane's control yoke from what the pilots had experienced training on simulators, possibly sowing confusion aboard Flight JT610. Boeing insists the plane is safe to fly. Appearing Tuesday on the Fox Business Network, Chief Executive Dennis Muilenburg called the MAX "very safe" and said Boeing provides "all of the information that's needed to safely fly our airplanes." Even the pilots at American Airlines and Southwest, who on Monday expressed concern that they had not been given prior information about the new flight control system, continue to fly the plane. They've been assured that a standard procedure Boeing highlighted after the Lion Air crash will turn off the system if it goes awry in the future and quickly return the jet to normal flight. Still, even though it may be no more than one element in a string of events that led to the Lion Air catastrophe, the new MAX flight control system has become a subject of intense controversy. Three former Boeing flight control experts were startled by the FAA's description last week of the new MAX system. In an airworthiness directive, the FAA cited an analysis by Boeing that "if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands" that will swivel the plane's horizontal tail to pitch the nose downward. The fact that the plane's nose could be automatically and repeatedly pushed down due to one false signal shocked Peter Lemme, a former Boeing flight controls engineer, who said it looks like a design flaw. "To contemplate commanding the (horizontal tail to pitch the jet) nose down clearly is a major concern. For it to have been triggered by something as small as a sensor error is staggering," Lemme said. "It means somebody didn't do their job. There's going to be hell to pay for that." Likewise, Dwight Schaeffer, a former Boeing electronics engineer and senior manager who oversaw development of systems, including the 737's stall management computer, said the brief description in the FAA's airworthiness directive "blows me away." "Usually you never have a single fault that can put you in danger," said Schaeffer. "I've never seen any such system." A former Boeing vice president who started as an avionics engineer - who asked for anonymity, because as a former executive he said he worries about being sued by the company for public criticism - said he is also surprised at the suggestion in the FAA wording of "a single point of failure" that could bring down an aircraft. But he added that he wouldn't necessarily call it a design flaw in itself, provided flight crews have the ability to recognize what's happening and have training to deal with it. Yet this too is a point of controversy. Boeing rushed out a bulletin last week to inform pilots all over the world about the new flight control system and exactly what to do to shut it down if it goes haywire. But the Lion Air crew didn't have that information and may have been confused by a key handling difference that the system could have caused during the flight. New flight controls Bjorn Ferhm, a former jet-fighter pilot and an aeronautical engineer who is now an analyst with Leeham.net, said the technical description of the new 737 MAX flight control system - called MCAS (Maneuvering Characteristics Augmentation System) - that Boeing released to airlines last weekend makes clear that it is designed to kick in only in extreme situations, when the plane is doing steep turns that put high stress on the airframe or when it's flying at speeds so low it's about to stall. Management at Southwest Airlines told its pilots that Boeing did not include any description of MCAS in the flight manual because a pilot "should never see the operation of MCAS" in normal flying. But in the extreme circumstances where it does activate, when the angle of attack hits the range of 10 to 12 degrees, the system rotates the horizontal tail so as to pitch the nose down. And if the high angle of attack persists, the system repeats the command every 10 seconds. Ferhm said Boeing must have added this system on the MAX because when the angle of attack is high this model is less stable compared to prior 737 variants. That's because the MAX has bigger, heavier engines that are also cantilevered further forward on the wing to provide more ground clearance. That changes the center of gravity. The scenario feared in the Lion Air case is that the AOA sensor sent false signals that fooled the computer into thinking the plane was in a dangerous stall position, and so MCAS was triggered. - https://www.seattletimes.com/busines...ion-air-crash/ |
16th November 2018, 10:27 |
#196
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Groupie Member
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Babak baru
Keluarga dari salah korban jatuhnya pesawat Lion Air JT 610 menggungat The Boeing Company Menurut Miner, perjanjian internasional, tidak memperbolehkan penyidik dari Indonesia untuk menentukan pihak yang bersalah atau yang bertanggung jawab atas kecelakaan pesawat. "Mereka hanya diperbolehkan untuk membuat rekomendasi keselamatan untuk industri penerbangan di masa depan," tutur dia. Pengacara Austin Bartlett juga menambahkan, The Boeing Company telah gagal memperingatkan klien dan pilot pesawat 737 MAX mengenai perubahan sistem kontrol penerbangan yang signifikan ini dan gagal menyampaikan instruksi yang benar dalam manualnya. |
16th November 2018, 16:36 |
#197
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Registered Member
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semuanya rusak, airspeed, manajemen, ticketing, reputasi . apa yang masih tersisa di lion air cuma deretan pesawat baru yang dioperasikan oleh manajemen amburadul. Mana sanksi tegas Untuk maskapai ini? Negara 1000 sloganism memang indo ini.
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17th November 2018, 07:02 |
#198
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Groupie Member
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During the three weeks before Lion Air Flight 610 plunged into waters off Indonesia, Southwest Airlines Co. replaced two malfunctioning flight-control sensors of the same type that has been publicly implicated in the crash, according to a summary of Southwest maintenance records reviewed by The Wall Street Journal.
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17th November 2018, 10:48 |
#199
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Mania Member
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Quote:
Sebenarnya ada ironi dibalik ini. Sebenarnya Southwest Airline [SWA] adalah pembeli pertama MAX8 dan seharusnya juga menjadi "launching operator" dari Boeing 737 MAX8, tetapi karena mereka merasa belum punya cukup waktu untuk melatih pilot-pilot nya untuk mengemudikan MAX8. Sebagian besar dari mereka adalah pilot-pilot dari varian NG, disamping itu TIDAK ADANYA FLIGHT SIMULATOR KHUSUS untuk MAX8 pada waktu itu - bahkan sampai detik inipun BELUM ADA SIMULATOR Boeing 737 MAX8 yang dibuat- maka Soutwest Airline memutuskan mengundurkan launching mereka sampai Agustus-September 2017. Maka Boeing menunjuk Lion Air Group sebagai launching operator MAX8. Pada bulan Mei 2017, Batik Air Malaysia menjadi operator pertama di dunia yang mengoperasikan MAX8. [Lion Air PK-LQK eks Batik Air Malaysia 9M-LRC] SWA punya sekitar 23 Boeing 737 MAX8 yang sedang terbang yang usianya sekitar 1 tahun atau lebih muda dari itu. Malah pada salah satu "penerbangan perdana" MAX8 mengalami masalah pada spoiler nya pada saat transit, sehingga penerbangan sambungan terpaksa dilanjutkan menggunakan pesawat lain. [baca disini] - http://www.boeing.com/company/about-...-05-17-17.page - https://airwaysmag.com/special-fligh...spoiler-alert/ |
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17th November 2018, 11:27 |
#200
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Groupie Member
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Quote:
Questions swirled on Wednesday (Nov 14) about how Boeing had failed to tell airlines and pilots about changes to an anti-stall system suspected in last month's fatal crash in Indonesia. Investigators are examining whether the system, which is meant to prevent aircraft from stalling, was tied to the crash of Lion Air flight 610. |
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