Boeing's New 777-X's Folding Wings, Are They Safe?

In the wake of two recent crashes seemingly caused by Boeing's design decisions for their 737 Max 8 and Max 9 airplanes, is it any wonder that people are concerned about Boeing's new models, the 777-8 and 777-9, that feature folding wing tips?

The reason for the folding wing tips is that the wingspan of the new aircraft, at 235 feet, is too long to fit at the gates of most airports. Once folded, the wings will be only 212 feet in length. The purpose of the longer wing is to reduce drag caused by vortices, or wake turbulence, that form at an aircraft's wing tips. The less drag, the greater the fuel efficiency, and the more cheaply the aircraft can be operated.

According to Boeing, the wings will only fold when the plane is on the ground, and jet fuel will not be stored within the folding sections. Normally, jet fuel is stored within the wings of an airplane. For years, military planes on aircraft carriers have had folding wings so that they take up less space.

To get approval for the folding wing from the U.S. Federal Aviation Administration, Boeing submitted a "Special Conditions" request, and the final decision by the FAA was made public on May 18, 2018 in the Federal Register...

This document has some pretty sobering language regarding the 777-8's and the 777-9's new design:

"Boeing has determined that a catastrophic event could occur if the Model 777-8 and 777-9 airplane wingtips are not properly positioned and secured for takeoff and during flight. In service, numerous takeoff operations with improper airplane configurations have occurred due to failures of the takeoff warning systems, or inadvertent crew actions.

Partially kidding — that was a bit tongue-in-cheek joke related to the two 737 MAX crashes...

The 737 MAX had two extra cost safety options related to the AOA sensor.
1. the AOA indicator that displays the AOA information on the main cockpit display.
2. a “disagree” light that activates when the information from the two AOA sensors aren’t in agreement.

The FAA did not make either of these optional sensors mandatory. Three US carriers approached the purchase of these upgrades on the 737 MAX differently.

• United, which had 14 MAX planes in service of the 137 ordered, did not purchase either upgrade.
• American Airlines, which had 24 planes in service out of its 100 ordered, purchased both.
• Southwest, with 36 planes already flying out of 280 ordered, initially purchased the disagree light. Then after the Lion Air crash, Southwest took a proactive measure in December of 2018 by adding the AOA indicator to the pilots’ main computer screens.

Please join me in prayer that Satan’s assignments of sabotaging air travel be declared moot in Jesus’ name. A truly Christian leader would have all of Boeing’s latest models re-inspected or recalled, their engineers back to the drawing boards, and the time and patience necessary to build new plane designs with passengers and the love of aviation in mind—not mere greed and short term financial expediency.

Boeing had in fact scrubbed their pursuit of a new design due to the fear of Airbus sales encroaching upon their share of the US-based airlines market...so rather than investing in that, they embellished upon their pre-existing models (like the 737) and made them aerodynamically compromised in the process as they force-fitted new engines etc...They added complicated yet haphazard software to offset the risks,without fully informing pilots of the changes. Awful.

Thanks for the info. I do have some experience in this area.

I worked aircraft instrumentation in the Air Force and mostly I remember from the F-4D. It had a single AOA probe.

At times the pilots would report an altimeter reading that would fluctuate wildly. One thing that can cause this is water buildup in the static pressure line. Just drain the water and test the system.

Another thing though was the AOA probe. To test we’d hook up to the static pressure system and simulate an altitude of, say, 20,000 feet. Then we’d slowly move the AOA probe through its range of motion. Sometimes you’d see the altimeter react wildly, say up 2,000 feet in 2 seconds, then back down several thousand feet just as fast. When that happened we knew there was a bad spot on the AOA probe. The pilot could switch the altimeter to standby which would make the altimeter use the straight static pressure for the display without using the AOA input.

We’d take the AOA probe into the shop and apply a voltage and then using an oscilloscope you could watch the output. It should be a smooth movement. If the AOA probe was dirty and had a bad spot on it you could see that the voltage would spike up or down wildly. Sometimes we could fix this with electrical contact cleaner, but not always.

AOA probes have heaters so that they work in the cold but the heaters don’t come on until the Weight-on-wheels switch indicates no weight. We had a high-tech way to turn on the WOW switch-jam in a screwdriver to force the switch to the no weight position.

The F-4 had an autopilot function called “altitude hold”. However, they were not allowed to use it below 10,000 feet. This probably had to do with these wild fluctuations caused by the above mentioned problems.

Without knowing I assumed the 737s had AOA indicators, but now that I think about it, I’m not the KC-135s that I worked on later had AOA indicators.

With the 737 MAX crashes, I would think that a “disagree” light would be more than a light. I would think it should automatically disconnect the autopilot system from using the AOA information, but I don’t know. Key word=”should”.

Do you know if the two 737 MAX airplanes that crashed had the “disagree” feature? Seems like I read where one of the flight crews disconnected the autopilot so that it didn’t use the AOA information but then turned it back on. I’m not sure.

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