This announcement just made by Boeing that the production of the 737 MAX will be suspended until the aircraft is certified by the FAA.
Up until now, Boeing was hopeful that they would receive certification to fly by the end of the year. The FAA told Boeing in a meeting last week that the 737 MAX would not be cleared to fly this year. There is no estimate of when the 737 MAX will be recertified.
The Groundings of the 737 MAX
The FAA along with other aviation authorities around the world grounded the 737 MAX after two fatal crashes. The suspected cause of the crashes was a new flight management system called the Maneuvering Characteristics Augmentation System or MCAS. MCAS was needed because the new LEAP-1B engines have a greater diameter than the former CFM-56 turbofan engines. Boeing needed to mount the LEAP-1B engines further forward and higher up to have adequate ground clearance. Fixing this problem created another problem, a disruption of airflow of the wings. The correct airflow over the wings is necessary to generate lift. To address the airflow problem, Boeing created the MCAS system to prevent aerodynamic stalling from too great of a climb rate.
The MCAS system software has been shown to be faulty and problematic. The system relied on only one sensor even though two are mounted on the 737 MAX nose. The MCAS fault annunciator was installed only as an option. MCAS has problems with actually working correctly. The system was to prevent the pilot from overpitching the nose but activated on faulty data. MCAS was not properly documented in the 737 MAX Quick Reference Handbook (QRH) also referred to as the Pilot Operating Handbook (POH). To make matters worse, there was no formal simulator training for pilots that were transitioning from previous models of the 737 to the new MAX models.
The result of the faulty operation of MCAS was in effect having the pilots fight against the computer-controlled pitch system. Since formal training was not offered, the pilots of the aircraft crashes had no idea what was going on, that MCAS was equipped on their aircraft or how to defeat MCAS. The results were that the computer was overpowering and out-commanding the pilots. Here is the ADS-B output of the final minute of flight for Lion Air 610:
When you have a flight management computer overruling pilot input, the computer is going to win. These pilots had no idea what was going on because they did not know that their aircraft were equipped with MCAS. Recertification of MCAS fixes will also have to address pilot training on MCAS.
I fly a Cessna 182T with the Garmin G1000 digital cockpit. If Garmin created a new version of the G1000 flight management system and didn’t tell me about that modification, I would not be able to understand what the aircraft is doing and why it is not properly acting on my pilot control inputs.
Why Doesn’t the Airbus A-320NEO Have the Same Issues?
The 737 is based on the Boeing 707 design from the 1950’s. Before 1969, high bypass ratio engines didn’t exist. The Boeing narrow-body aircraft sit low to the ground and that wasn’t a problem until high bypass ratio turbofans were developed. The Boeing 757 was the exception because it was designed and built for high bypass ratio engines. Since the A320 family was designed in the 1980’s, Airbus designed these aircraft will taller landing gear height to accommodate the increased diameter of high bypass ratio turbofan engines.
Suspending 737 MAX Production
With over 400 completed 737 MAX aircraft sitting on the ground, Boeing is running out of room to store completed aircraft. For the time being, Boeing will shift its focus to final completion work on the completed airframes. Even though Boeing has a healthy reserve of cash, suspending production makes sense since Boeing isn’t receiving payments of the aircraft until they are delivered.
Will the 737 MAX Fly Again and Can You Trust It?
The Boeing 737 aircraft is the most successful airliner in history. Boeing has a tremendous backlog of 737 MAX orders and they are the bread and butter of sales at Boeing. The 737 MAX will be recertified to fly as commercial transports when all of the governing aviation bodies are ready to certify the aircraft. When the 737 MAX flys again, it will be the most scrutinized passenger aircraft ever built and should be considered a safe aircraft. Pilots will need to receive adequate simulator training to understand how MCAS should assist in human control of the aircraft. At this time, there is no date on when the 737 MAX will return to service.