Kraków 2020-08-25
Boeing 737 MAX
History
The war of giants.
In 2016, the Airbus concern introduced the A-320 NEO plane to the market, i.e. a heavily modernized version, with new engines, lower fuel consumption by about 15% and other changes. In three years, Airbus has delivered over 600 copies to the airlines, winning orders for nearly 6,000 more. And although the planes were plagued by childhood diseases, the planes flew safely.
Worldwide, the B-737 takes off every 2 seconds. There are 1,200 B-737 aircraft in the air at one time. Airlines value it for its ease of use, relatively low service costs and, above all, legendary failure-free operation. The Boeing B-737 is the world's most popular passenger plane. To date, 10,478 of these aircraft have been delivered and most are still flying. Airbus A-320 is in second place, with 8,605 aircraft built and mostly still flying.
The Boeing concern gave the next generations the following names: Original, Classic, Next Generation. The changes were quite radical. From new engines, to structural and aerodynamic changes, to completely revamped avionics. The Americans started working on the next modernization of the B-737 MAX. Boeing followed the same path as Airbus, focusing on lower fuel consumption and overall operating costs. Regular customers of the American manufacturer lined up. Ryanair has announced that it will purchase 210 of the new B-737 MAX.
The B-737 MAX 8, made its first flight on January 29, 2016, and entered passenger service with Malindo Air on May 22, 2017. The aircraft can accommodate from 162 to 210 passengers, depending on the configuration. One version has a range of up to 3,850 nautical miles, i.e. a flight across the Atlantic or a cruise between the USA and Hawaii.
The world troubles of the Boeing B-737 MAX.
On October 28, 2018, the Lion Air B.737 MAX PK-LQP aircraft operator performed a cruise flight. Shortly after the start, the vibrator of the steering column (stick shaker) on the captain's side began to vibrate. Stick shaker are designed to warn pilots about an impending stall. But the plane flew normally. The captain ignored it. About 30 seconds later, the captain noticed an alarm on his flight display - IAS DISAGREE - which meant that the on-board computer had detected a sensor fault. It required a bit more attention.
A modern-day passenger airplane is less like a racecar and more like a 3D printer: you spend more time monitoring and checking systems than you do actually driving the thing.
So the captain passed control of the aircraft to the first officer and began the troubleshooting process from memory.
Like all commercial aircraft, the Boeing 737 MAX has multiple levels of redundancy for its important systems. In the cockpit, there are three flight computers and digital instrument panels operating in parallel: two primary systems and one backup. Each system is fed by an independent set of sensors.
In this case, the captain checked both instrument panels against the backup, and he found that the instruments on his side — the left side — were getting bad data. So with the turn of a dial, the captain switched the primary displays to only use data from the working sensors on the right side of the airplane.
Everything appeared to be back to normal.
At 1,500 feet of altitude, the takeoff portion of the flight was complete, and the first officer began the initial climb. He adjusted the throttle, set the aircraft on its optimal climb slope, and retracted the flaps.
However, the plane did not climb. It lurched downward, its nose pointed toward the ground.
The first officer reacted instinctively. He flicked a switch on his control column to counteract the dive. The airplane responded right away, pitching its nose back up. Five seconds later, it dove once again. The first officer brought the airplane’s nose up a third time.
The captain reached for the airplane’s Quick Reference Handbook (QRH). The QRH is a series of simple checklists that are designed to help pilots rapidly assess and manage “non-normal” situations. But nothing in the QRH seemed to apply, either.
Over the next six minutes, as the first officer struggled to control the airplane and the captain searched for the right checklist, PK-LQP climbed and dove over a dozen times.
The flight crew had to figure something out fast before they lost control of the airplane.
Then the third person in the cockpit, reportedly spoke up - What about the runaway stabilizer checklist?
Another checklist. “Runaway trim” occurs when some kind of failure causes an airplane’s horizontal stabilizer to move — or “trim” — when it shouldn’t be moving at all.
The PK-LQP problem was slightly different, but the crew ran out of ideas. They followed the checklist and switched the STAB TRIM to CUT OUT switches on the center console. The plane stopped falling. Five seconds passed. Then five minutes. Once again, PK-LQP was under their control and out of danger.
An hour later, Lion Air flight 043 landed in Jakarta, Indonesia. Following standard procedure, the captain reported the episode to the airline, and the airline’s maintenance team checked for serious equipment failures, finding none.
Boeing B.787 MAX PK-LQP catastrophe.
On October 29, 2018, PK-LQP, operating as a Lion Air 610 flight, took off at 6:20 local time on the way to Pangkal Pinang in Indonesia. Shortly after the start he threw a lot of mistakes on the flight display. The plane dived just after the flight crew pulled back the flaps. Within eight minutes, the plane was diving, it was rising.
This time, there was no third pilot to help the flight crew.
PK-LQP could reach 600 miles per hour. The plane got stuck in the water. It was the first 737 Max accident in the 18-month service period.
It was a shock for the lay people. But those who are closer to the development of the plane knew better: from the very beginning there were warning signs.
Disaster in Ethiopia Boeing B.737 MAX ET-AVJ.
Then on March 10, 2019, there was a disaster again. ET-AVJ, another 737 MAX 8 owned by Ethiopian Airlines, took off from Addis Ababa, Ethiopia, heading for Nairobi, Kenya. It was led by Yared Getachew, the youngest airline captain. To his right was Ahmed Nur Mohammed, a completely new first officer.
The stick shaker on the left control column activated just after takeoff. The altitude and AoA indicators on one side of the airplane malfunctioned. About 90 seconds after takeoff, and immediately after the first officer retracted the flaps, the airplane dove unexpectedly.
Instinctively, Captain Getachew pulled his control column back to point the nose skyward, then flicked the electric trim switch on his yoke. First Officer Mohammed, meanwhile, radioed air traffic control. “Request back to home. Request vector for landing.”
The captain switched the trimming switch several times. However, when the pilots gained tens of meters, the MCAS again directed the aircraft nose down.
Which was important. The crew with little experience correctly diagnosed the problem and acted correctly. But at some point the plane went into diving again and reached speeds of over 400 mph. The crew and passengers did not have any chance to save. None of the 157 people aboard survived.
At the crash site itself, relatives set up an arch wreathed in flowers as a memorial, under which they placed photographs of their loved ones. The airplane had struck the ground with so much force that there were no identifiable remains. Instead, families received bags of soil from the surrounding fields.
Boeing B.737 MAX Anatomy.
Boeing’s 737 and Airbus’ A320 are the two main players in the massive market for narrow-body passenger jets. Together, both airplanes comprise nearly half of the world’s 28,000 commercial airliners.
Both manufacturers are locked in a race to make their airplanes cheaper for airlines to operate, especially when it comes to fuel.
So Airbus and Boeing constantly tweak their airplanes to squeeze single percentage-point gains out of them.
On December 1st, 2010, Airbus stunned the aviation community. In secret, it had developed a more efficient version of the A320 called the A320neo (which stands for “new engine option”). It would burn about 6 percent less fuel than the 737NG.
As early as 2011, Airbus had a record number of 667 sold A.320 neo aircraft. Boeing had significantly fewer orders. The Boeing bosses began to wonder what to do. Whether to build a new aircraft or to modernize B.737 for the fourth time? The Boeing Company would launch a fourth-generation 737, and it would do it in record time.
Boeing could save billions of dollars in engineering costs by basing the MAX off of the B.737 platform. That gave the company a head start on design and engineering work — enough, Boeing hoped, to allow the MAX to enter service just months after the A.320 neo.
But the project’s engineers would have to overcome some monumental challenges in order to deliver on time.
At the same time, the engineers couldn’t update it too much. By law, a pilot can only fly one type of airplane at a time. However, the Federal Aviation Administration allows different models of airplanes with similar design characteristics to share a common “type certificate.” So, for instance, the 737’s three previous generations all have a common type certificate. When you get qualified on one model, you can fly all of them.
For this reason the Boeing B.737 MAX had to be similar to Boeing 737 NG (1993), Boeing 737 Classic (1980) and Boeing 737 (1964).
The first results were encouraging. Boeing promised that MAX will be 8 percent more efficient than A.320 neo. It has been estimated that after just 2.5 hours of computer training, the pilot can sit on the MAX controls.
This situation was greatly appreciated by the operators. The pilot can train at home and next day fly a new MAX plane.
What's the problem?
MAX was designed on the basis of new engines, which were marked LEAP-1B. They are much more efficient than the engines in the B.737 NG, but they are also much heavier and larger. The engines in B.737 NG hang above the ground just 18 inches away. Reconstruction of the wings was not an option. The reconstruction of the main chassis was also not taken into account. Only the shins of the front chassis have been extended a little.
In this situation, the engines moved forward, more in front of the wing. And so the engine fan has a diameter of about 1.80 m, while the A.320 neo has a diameter of 2.00 m.
That solution created an aerodynamics problem. Due to their size and position, the engines on the Max create lift when the airplane enters a steep climb (or, in aviation parlance, at high angles of attack). This extra lift causes the Max to handle differently than previous versions of the B.737, but only when it’s climbing steeply.
For this reason, Boeing developed the MCAS program, which pilots did not need to know about. So MCAS was designed to compensate. An angle of attack (AoA) sensor was used to detect when the plane entered steep climb. It activates the airplane's trim system. Trimming is a classic way of stabilizing the plane. The MCAS system was to operate for a few seconds until the angle of attack decreased. It seems simple enough — on paper, that is.
After the second crash, on March 13, 2019, the FAA grounded all MAX planes. Previously, this was done by the European Aviation Agency.
On April 17, 2019, Boeing completed flight tests with improved software.
Written by Karol Placha Hetman
Kraków 2020-08-25
326 Section 2017-12-01
Boeing B.737 MAX 8
Construction
Construction Boeing B.737 MAX 8.
The Boeing B-737 MAX is a mid-range and long-range twin-engine turbojet aircraft. The plane is built in the classic layout as a twin-engine low-wing.
Written by Karol Placha Hetman
Kraków 2020-08-25
326 Section 2017-12-01
Boeing B.737 MAX 8
Tally
The tally is in the previous section.
Written by Karol Placha Hetman