FAA urges airlines to follow Boeing’s advice.
11-07-2018, 06:29 AM
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FAA urges airlines to follow Boeing’s advice.
FAA Urges Airlines to Follow Boeing's Advice After 189 People Killed in 737 MAX Crash
https://apple.news/ATJlYlAm8T_2tqu9wlYJCOQ
A malfunctioning sensor may have been to blame
Bloomberg
A U.S. aviation regulator plans to mandate that airlines follow an advisory issued by Boeing Co. on how pilots should handle false readings from a plane sensor that authorities say occurred on a 737 MAX jet that crashed off the Indonesian coast last week.
The Federal Aviation Administration on Wednesday issued a statement saying it plans to issue an airworthiness directive on the issue and “will take further appropriate actions depending on the results of the investigation.” The FAA also notified other regulatory agencies around the world, which typically follow the U.S. agency’s lead on safety matters.
The operations-manual bulletin was issued Tuesday, Boeing said in a statement posted to Twitter, and tells flight crews to use existing guidelines when dealing with erroneous inputs from the so-called angle of attack sensor. That sensor is intended to maintain air flow over a plane’s wings but if it malfunctions it can cause the plane’s computers to erroneously think it is in a aerodynamic stall — which can then cause aircraft to abruptly dive.
Bloomberg News earlier reported that Boeing was said to be preparing to issue an alert to operators of the 737 MAX jet in response to the investigation into the Oct. 29 crash of the Lion Air plane, which saw 189 people killed.
The bulletin is based on preliminary findings from the Lion Air disaster. Under some circumstances, such as when pilots are flying manually, the MAX jets will automatically try to push down the nose if they detect that an aerodynamic stall is possible, a person familiar with the matter said. One of the critical ways a plane determines if a stall is imminent is the angle of attack measurement.
Boeing shares rose less than one percent to $368.11 in premarket trading Wednesday in New York. The stock had climbed 24 percent this year through Tuesday.
Lion Air Jet’s Final Plunge May Have Reached 600 Miles Per Hour
The Lion Air 737 MAX 8 jetliner plunged into the Java Sea minutes after takeoff from Jakarta airport, nosing downward so suddenly that it may have hit speeds of 600 miles an hour before slamming into the water. Moments earlier, the pilots radioed a request to return to Jakarta to land, but never turned back toward the airport, according to Indonesia’s National Transportation Safety Committee and flight-track data. The committee said the pilots were dealing with an erroneous airspeed indication.
The probe into what happened with the Lion Air plane “is ongoing and Boeing continues to cooperate fully and provide technical assistance at the request and under the direction of government authorities investigating the accident,” the company said in its statement.
Crashed Lion Air Jet Had Faulty Speed Readings on Last 4 Flights
The jet reported a discrepancy in its angle of attack sensor during a flight from Bali to Jakarta the day before it crashed. The device was replaced in Bali after pilots reported a problem with airspeed reading, the Indonesian transportation safety regulator said Wednesday.
Boeing has delivered 219 MAX planes — the latest and most advanced 737 jets — since the models made their commercial debut last year with a Lion Air subsidiary. Boeing has more than 4,500 orders for the airliners, which feature larger engines, more aerodynamic wings and an upgraded cockpit with larger glass displays. The single-aisle family is Boeing’s biggest source of profit.
Aircraft and engine manufacturers routinely send bulletins to air carriers noting safety measures and maintenance actions they should take, most of them relatively routine. But the urgency of a fatal accident can trigger a flurry of such notices.
After an engine on a Southwest Airlines Co. plane fractured earlier this year over Pennsylvania, killing a passenger, CFM International Inc. issued multiple bulletins to operators of its CFM56-7B power plants.
Aviation regulators such as the U.S. FAA and the European Aviation Safety Agency often follow such actions by mandating that carriers follow the bulletins.
Pilots raise and lower the nose of Boeing jetliners by pushing and pulling on a yoke in the cockpit, which controls panels at the tail known as elevators. In addition, a system known as elevator trim can be changed to prompt nose-up or nose-down movement.
The angle of attack readings are fed into a computer that in some cases will attempt to push down the nose using the elevator trim system. In the early days of the jet age, the elevator trim system was linked to several accidents. If pilots aren’t careful, they can cause severe nose-down trim settings that make it impossible to level a plane.
Such an issue arose in 2016 at Rostov-on-Don Airport in Russia when a FlyDubai 737-800 nosed over and slammed into the runway at a steep angle, according to an interim report by Russian investigators. That case didn’t involve the angle-of-attack system. One of the pilots had trimmed the plane to push the nose down while trying to climb after aborting a landing, the report said. All 62 people on board died.
https://apple.news/ATJlYlAm8T_2tqu9wlYJCOQ
A malfunctioning sensor may have been to blame
Bloomberg
A U.S. aviation regulator plans to mandate that airlines follow an advisory issued by Boeing Co. on how pilots should handle false readings from a plane sensor that authorities say occurred on a 737 MAX jet that crashed off the Indonesian coast last week.
The Federal Aviation Administration on Wednesday issued a statement saying it plans to issue an airworthiness directive on the issue and “will take further appropriate actions depending on the results of the investigation.” The FAA also notified other regulatory agencies around the world, which typically follow the U.S. agency’s lead on safety matters.
The operations-manual bulletin was issued Tuesday, Boeing said in a statement posted to Twitter, and tells flight crews to use existing guidelines when dealing with erroneous inputs from the so-called angle of attack sensor. That sensor is intended to maintain air flow over a plane’s wings but if it malfunctions it can cause the plane’s computers to erroneously think it is in a aerodynamic stall — which can then cause aircraft to abruptly dive.
Bloomberg News earlier reported that Boeing was said to be preparing to issue an alert to operators of the 737 MAX jet in response to the investigation into the Oct. 29 crash of the Lion Air plane, which saw 189 people killed.
The bulletin is based on preliminary findings from the Lion Air disaster. Under some circumstances, such as when pilots are flying manually, the MAX jets will automatically try to push down the nose if they detect that an aerodynamic stall is possible, a person familiar with the matter said. One of the critical ways a plane determines if a stall is imminent is the angle of attack measurement.
Boeing shares rose less than one percent to $368.11 in premarket trading Wednesday in New York. The stock had climbed 24 percent this year through Tuesday.
Lion Air Jet’s Final Plunge May Have Reached 600 Miles Per Hour
The Lion Air 737 MAX 8 jetliner plunged into the Java Sea minutes after takeoff from Jakarta airport, nosing downward so suddenly that it may have hit speeds of 600 miles an hour before slamming into the water. Moments earlier, the pilots radioed a request to return to Jakarta to land, but never turned back toward the airport, according to Indonesia’s National Transportation Safety Committee and flight-track data. The committee said the pilots were dealing with an erroneous airspeed indication.
The probe into what happened with the Lion Air plane “is ongoing and Boeing continues to cooperate fully and provide technical assistance at the request and under the direction of government authorities investigating the accident,” the company said in its statement.
Crashed Lion Air Jet Had Faulty Speed Readings on Last 4 Flights
The jet reported a discrepancy in its angle of attack sensor during a flight from Bali to Jakarta the day before it crashed. The device was replaced in Bali after pilots reported a problem with airspeed reading, the Indonesian transportation safety regulator said Wednesday.
Boeing has delivered 219 MAX planes — the latest and most advanced 737 jets — since the models made their commercial debut last year with a Lion Air subsidiary. Boeing has more than 4,500 orders for the airliners, which feature larger engines, more aerodynamic wings and an upgraded cockpit with larger glass displays. The single-aisle family is Boeing’s biggest source of profit.
Aircraft and engine manufacturers routinely send bulletins to air carriers noting safety measures and maintenance actions they should take, most of them relatively routine. But the urgency of a fatal accident can trigger a flurry of such notices.
After an engine on a Southwest Airlines Co. plane fractured earlier this year over Pennsylvania, killing a passenger, CFM International Inc. issued multiple bulletins to operators of its CFM56-7B power plants.
Aviation regulators such as the U.S. FAA and the European Aviation Safety Agency often follow such actions by mandating that carriers follow the bulletins.
Pilots raise and lower the nose of Boeing jetliners by pushing and pulling on a yoke in the cockpit, which controls panels at the tail known as elevators. In addition, a system known as elevator trim can be changed to prompt nose-up or nose-down movement.
The angle of attack readings are fed into a computer that in some cases will attempt to push down the nose using the elevator trim system. In the early days of the jet age, the elevator trim system was linked to several accidents. If pilots aren’t careful, they can cause severe nose-down trim settings that make it impossible to level a plane.
Such an issue arose in 2016 at Rostov-on-Don Airport in Russia when a FlyDubai 737-800 nosed over and slammed into the runway at a steep angle, according to an interim report by Russian investigators. That case didn’t involve the angle-of-attack system. One of the pilots had trimmed the plane to push the nose down while trying to climb after aborting a landing, the report said. All 62 people on board died.
11-07-2018, 12:16 PM
#3
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Interesting article but the facts need to get sorted out.
Alpha vane (AOA sensor) malfunction or Airspeed anomaly? Article said the Pilots wrote up the AOA sensor and it was replaced, but also said it was an Airspeed problem. Either malfunction could result in a stall indication.
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Alpha vane (AOA sensor) malfunction or Airspeed anomaly? Article said the Pilots wrote up the AOA sensor and it was replaced, but also said it was an Airspeed problem. Either malfunction could result in a stall indication.
Sent from my iPhone using Tapatalk
11-14-2018, 08:00 AM
#6
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Posts: 281
The AD has already been issued - Emergency AD 2018-23-51, November 7, 2018.
Blaming a serious flight control problem on the AOA vane and then flying with pax without a test flight seems extremely poor maintenance practices.
I don't know what troubleshooting was done but it seems like tests with a pitot static system test box with power and hydraulic power on the aircraft might have been tried to see if the problem could be duplicated before changing out components (and afterwards as well) before flight. It would probably be necessary to bypass the landing gear squat switch and pinning the gear just to be on the safe side.
In any event they have the original AOA vane that was replaced and can check to see if it was functional or not. The chances of it being bad and the replacement being bad are not high.
Blaming a serious flight control problem on the AOA vane and then flying with pax without a test flight seems extremely poor maintenance practices.
I don't know what troubleshooting was done but it seems like tests with a pitot static system test box with power and hydraulic power on the aircraft might have been tried to see if the problem could be duplicated before changing out components (and afterwards as well) before flight. It would probably be necessary to bypass the landing gear squat switch and pinning the gear just to be on the safe side.
In any event they have the original AOA vane that was replaced and can check to see if it was functional or not. The chances of it being bad and the replacement being bad are not high.
Last edited by F4E Mx; 11-14-2018 at 08:12 AM.
11-14-2018, 08:13 AM
#7
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Originally Posted by F4E Mx
I don't know what troubleshooting was done but it seems like tests with a pitot static system test box with power and hydraulic power on the aircraft....
Since there's no pitot or static component to an AOA vane, why would that be necessary? Why hydraulic power as well?
Isn't an AOA vane basically just taking a direct reading of relative wind in relation to wing chord?
11-14-2018, 08:34 AM
#8
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You are correct about the AOA vane, but the fact that it was changed out and the problem remained indicates it likely was not a factor. Using the pitot static test boxes with hydraulic and electrical power on the aircraft and with the squat switch bypassed (so the aircraft does not think it is on the ground) you can apply what ever pitot and static pressure you want to mimic the speed and altitude the problem occurred and go from there. You could also move the AOA vane to generate an input from the vane into the control system. I would want a Boeing engineer on the phone while doing these tests but something definitive should have been found and corrected before releasing the aircraft for a test flight, never mind one with passengers on board.
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