Boeing Faces Trouble After US Regulators Uncover ‘Potential Risk’
The US Federal Aviation Administration (FAA), has recently uncovered another potential defect in Boeing’s 737 Max plane, prompting United Airlines to prolong its ban on working with the aircraft.
United Airlines is the latest carrier to stop using the 737 Max aircraft, following in the footsteps of American and Southwest airlines who have extended their ban of the plane for the next 2 months, as the Federal Aviation Administration published a statement on the Boeing 737 Max on June 26th.
‘The FAA is following a thorough process, not a prescribed timeline, for returning the Boeing 737 Max to passenger service. The FAA will lift the aircraft’s prohibition order when we deem it is safe to do so. We continue to evaluate Boeing’s software modification to the MCAS and we are still developing necessary training requirements. We also are responding to recommendations received from the Technical Advisory Board (TAB). The TAB is an independent review panel we have asked to review our work regarding 737 Max return to service.’
‘On the most recent issue, the FAA’s process is designed to discover and highlight potential risks. The FAA recently found a potential risk that Boeing must mitigate.’
Taken from the FAA website.
‘Nothing is more important to us than the safety of our customers and employees. As we have said since Sunday, we have been in close contact with investigators as well as Boeing to share data and fully cooperate with regulatory authorities. We will comply with the FAA’s order and will ground our 14 Boeing 737 MAX aircraft. We will remain in close contact with authorities as their investigation continues.’
‘Since Sunday, we have been working diligently on contingency plans to prepare our fleet to minimize the impact to customers. Our Boeing 737 MAX aircraft account for roughly 40 flights a day and through a combination of spare aircraft and rebooking customers, we do not anticipate a significant operational impact as a result of this order. We will continue to work with our customers to help minimize any disruption to their travel plans.’ Said United Airlines in a statement on March 13th, 2019.
With United’s ban of the aircraft until early September, nearly 2 thousand planned flights were cancelled. Boeing has faced intense pressure and scrutiny after two of its 737 Max aircraft were involved in fatal crashes on March 10, 2019, in Ethiopia and October 29, 2018 in Indonesia.
The FAA uncovered the risk after carrying out simulator trial and error tests but was unsure as to whether the flaw could be resolved through software updates or if more elaborate hardware upgrades were necessary to solve the issue.
The US regulatory body did not specify any further details regarding the ‘potential risk’, as Boeing has been struggling to improve the quality and competency of its 737 Max aircraft after 2 deadly accidents.
The latest problem effectively prevents Boeing from carrying out any further certification trial flights until next month which will then be followed by extensive reviews and checks by the Federal Aviation Administration for nearly a month before they can approve the aircraft as fit and safe for service.
Dan Elwell, FAA Administrator on the 23rd of May gave the following statement at a Directorates General Meeting:
‘What happens next is that, here in the U.S., we await Boeing’s completed for changes to the MAX. Once received we perform our final risk assessments and analyses, taking into account findings of the TAB and any information we receive from our international counterparts. We’ll also take part in test flights of a modified 737 MAX and weigh all the information together before making the decision to return the aircraft to service.’
‘Internationally, each country has to make its own decisions, but the FAA will make available to our counterparts all that we have learned, all that we have done, and all of our assistance under our International Civil Aviation Organization commitments.’
‘As all of us work through this rigorous process, we will continue to be transparent and exchange all that we know and all that we do –to strengthen the public’s confidence that the aircraft will meet the highest safety standards.’
Since then Boeing has been trying to develop an updated version of the MCAS system which is believed to have been responsible for the two tragic crashes in Ethiopia and Indonesia.
What is Boeing’s MCAS system? The Boeing 737 Max Maneuvering Characteristics Augmentation System is a flight control system that is designed to help the pilots of the aircraft control the AoA (Angle of Attack) when flying to reduce the probability of stalling.
Boeing’s engineers had fuel economy in mind when designing and developing the 737 Max jet, which meant that they needed to figure out how to install a large economical engine underneath the wings. So, they positioned the engine further forward which meant that they had to expand the front landing gear by just under 10 inches. As a result of these modifications, Boeing managed to cut fuel consumption by roughly 15 percent.
However, the alterations also had an impact on the aircraft’s handling. The new position and structure of the engines made the aircraft’s front end lean upwards during flight. So, in an effort to counteract this side effect Boeing installed its MCAS system designed to give 737 Max pilots a helping hand during circumstances where the angle of the aircraft’s nose was too high increasing the risk of stalling.
‘MCAS (Maneuvering Characteristics Augmentation System) is implemented on the 737 MAX to enhance longitudinal stability characteristics with flaps UP and at elevated Angles of Attack (AoA). The MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors and during flaps up flight at airspeeds approaching stall. MCAS is activated without pilot input and only operates in manual, flaps up flight. The system is designed to allow the flight crew to use column trim switch or stabilizer aislestand cutout switches to override MCAS input. The function is commanded by the Flight Control Computer (FCC) using input data from sensors and other airplane systems.’
‘The MCAS function becomes active when the AoA exceeds a threshold based on airspeed and altitude. MCAS will activate for up to 9.26 seconds before pausing for 5 seconds. Stabilizer incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer input is lower at high Mach number and greater at low Mach numbers (for the same AoA above the activation threshold).’
‘After AoA falls below the hysteresis threshold (0.5 degrees below the activation angle), MCAS commands nose up stabilizer to return the aircraft to the trim state that existed before the MCAS activation.’
‘The function is reset once the angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation.’
To read Boeing’s full report on its MCAS system, click here.
It is uncertain as to how the MCAS system issue will be resolved, adding to the possibility for delays and additional carriers banning the usage of the 737 Max jet until the FAA gives its approval.
Boeing’s Chief Executive Officer, Dennis Muilenburg, in an interview with CBS Evening News on May 29th said:
“We can’t change what happened in these accidents, but we can be resolute in what we are going to do on safety going forward. We are stepping up and taking responsibility, we know we have improvements we can make and we will make those improvements. The implementation of the MCAS software and the Angle of Attack disagree alert was a mistake, we did not do it correctly, our engineers discovered that and our communication on that was not what it should have been.”
Click here to watch the full interview.