A Look At The Testing New Aircraft Must Undergo

With millions of flights every year and thousands of aircraft, it can be easy to forget that every plane goes through rigorous testing before flying commercially. As the industry has significantly innovated over the past few decades, modern aircraft are tested across a variety of scenarios to ensure that they operate safely and properly. Once testing is complete, manufacturers will analyze data and confirm that the aircraft is meeting expectations. If there are any discrepancies, the jet will be subject to additional flight testing.

It takes several years from the inception of an aircraft to when it is delivered to an airline. Manufacturers will build prototypes of the aircraft and use them as testbeds to prove the plane’s integrity. Testing does not just occur in one location, but rather around the globe to experience different environments and elevations. One modern aircraft that it currently going through testing is the highly anticipated Boeing 777X.

A variety of tests

Despite some challenges and setbacks, the US planemaker has been making progress toward certification of its newest widebody aircraft. Boeing officials expect the 777X to become the flagship aircraft of several airlines. However, before it can assume the title, the plane must be tested, with its functionality in all environments being a major component.

The Boeing 777X test aircraft

Photo: Jonathan Hendry | Simple Flying

For example, Boeing has already tested how the aircraft might perform in icy conditions by putting an inch of ice on portions of the wings. Results found that the jet has been reliable throughout the testing process, prompting Boeing to believe that its customers will be happy with its performance.

Boeing has four test 777X aircraft or prototypes. Each are used for a variety of specific tests:

  • Aircraft one and two are the workhorses of the fleet, having performed the bulk of the testing
  • Aircraft three focuses on engine and load testing and will be used to perform some of the first certification flight tests
  • Aircraft four has an interior that is used for cabin testing. It is also used for hot weather and cold weather tests

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Environmental tests on the 777X have taken place across North America. According to Boeing, cold weather testing was done in Fairbanks, Alaska, while hot weather tests were performed in Yuma, Arizona. The manufacturer plans to undergo the testing again for Federal Aviation Administration (FAA) certification – the agency will make sure that the aircraft complies with all regulations before it can be certified for commercial operations.

Given Boeing’s severe complications with the 737 MAX and 787 Dreamliner, the FAA is likely to crack down on the 777X certification. Boeing is still yet to have the 737 MAX 7 and MAX 10 – the smallest and largest variants of the aircraft family – certified by the agency.

Takeoff performance and ground effects

Takeoff performance testing has taken place at Edwards Air Force Base in Kern County, California. The base has a long runway and a dried-up lake bed at the end of it should any testing go awry. Boeing says that takeoff performance testing is one of its most challenging tests.

It includes tail strike testing, which involves a tail skid mounted to the back of the 777X prototype. It is used to observe the structural capability of the aircraft. The company will also practice scenarios with the tail skid, such as rotating too early, too late, or using high or low thrust.

Boeing 777X in flight

Photo: Tom Boon | Simple Flying

Ground effects testing involves analyzing the aircraft’s brakes on wet and dry runways. Wet runway tests are performed in Roswell, New Mexico, while dry runway tests have been conducted in central Oklahoma. Brad Till, Boeing’s Managing Director of Commercial Airplanes, explained how this testing process can also be challenging.

“Both challenging conditions to fly. Really why we do this is to validate our engineering analysis that the brakes perform as you’d expect, which they’ve done very well, and we’ll do this again with the regulators.”

Boeing 777X landing at BFI shutterstock_1846883377

Photo: BlueBarronPhoto | Shutterstock

Wet runway testing can be complex because it involves timing coordination. Trucks will saturate the runway with water, but pilots only have a minute to land the aircraft before the water runs off. A specific water depth is key to adequate testing of the aircraft’s performance.

Crosswinds & high-elevation

Crosswind testing has been conducted in Lubbock, Texas because the airport has perpendicular runways. While all commercial aircraft land to the wind, Boeing has restricted access to the other runways for testing. The aircraft was pushed to its potential as cross winds were 30-40 knots when Boeing last performed the tests.

“We’ll demonstrate all the landing techniques that Boeing recommends, either aligning with the runway early on final or aligning while you’re in the flare, or landing in a full crab, which is…well over 10 degrees of drift angle,” Till explained.

Boeing has sent the 777X to locations such as Colorado Springs and Toluca, Mexico, for high-elevation tests. In February, one of the prototypes, registered as N779XX, visited Colorado Springs Municipal Airport (COS). It performed eight takeoffs and eight landings, taking advantage of runway 17L, which is 13,500 feet long. Higher elevation altitudes require longer runways as the aircraft operates at different air pressures, which affects takeoff.

More recently, the 777X visited Toluca for high-altitude performance flight testing. Due to its altitude – 8,790 feet above sea level – the city is one of the coolest in Mexico. Manufacturers commonly send aircraft there for testing as it is one of the highest-elevation cities for commercial aircraft operations.

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