The plane that costs millions of dollars to Boeing has received authorization again.
As some of you may have noticed, Boeing’s crown jewel, the 737Max, is again on the skies. The past 18 of November, the FAA (Federal Aviation Administration) finally revoked this plane’s prohibition to fly since March of 2019 after two fatal accidents, first in Indonesia 2018 and the last one in Ethiopia 2019, both with no survivors, summing 346 deceased.
Therefore, what was the trouble with this acclaimed aircraft?
Even though it may seem, the 737M’s major strength was its weakness. This plane’s philosophy is to reach the highest possible performance, so does its engines, that’s why they are so huge. Making it easy, in the aerospace industry: bigger engines means bigger performance, that’s because of the Bypass Ratios (BPR) which is 5:1 for the 737M’s engines.
More means better, isn´t it easy? Not so fast, if for older versions of the 737, engines were dangerously close to the ground, 737M’s ones would be closer, so that Boeing designers decided to displace them forward and upward making them stand out of the wingspan: more horizontal surface in contact with the air traduces into more lift.
Not that bad.
However, that lift can make the aircraft’s nose rise more than needed, a thing that we don’t want but that we are used to fixing; so is why trim tabs exist since almost the invention of aircraft. Nevertheless in Boeing’s B737M the trim needed to counter the extra-lift of both engines is controlled by an informatic software called MCAS (Manoeuvring Characteristics Augmentation System), which instead of moving the pitch trim, takes control of the elevator ignoring the pilot and automatically uses it to pull down the nose when it detects a higher angle of attack than specific values.
After all, this shouldn’t be the cause of a fatal accident, but because of a defect in the instrument that measures the AOA (Angle of attack), it leads to a misfunctioning of the MCAS which pulls the aircraft into the ground.
If we also add that most of the pilots were not trained into this new system and most of them didn’t even know its existence, we have mortal accidents.
To end, we have to mention all the losses that this failure has caused to Boeing and all the airlines that bought a plane, all this coincided in time with the Covid-19 pandemic. This is traduced into almost total cancellations of flights and astronomic money-losing for Boeing and its clients.
After all, the B737Max seems to start seeing the light at the bottom of the tunnel and will be back in airlines during 2021.