US aircraft manufacturer Boeing’s testing program for its upcoming 777X flagship widebody is well underway. The manufacturer has completed four test aircraft, each with a different role in the certification process and set of test equipment. The planes are registered to highlight the 777-9X designation uniquely and are given sequential final letters corresponding to the last letters of the alphabet. Collectively, they have completed over 3,500 hours of flight tests across 1,200 sorties in preparation for FAA certification, which began last month.
Airplane One: N779XW
The very first 777X aircraft to roll out was anointed with the manufacture serial number 64240 and the unique registration of N779XW. All four models are of the Boeing 777-9 designation, with the smaller 777-8 to follow at a later date. Simple Flying was on hand for the first flight of a 777X test plane, which occurred on January 25th, 2020
Since its first flight, the aircraft has continued to conduct test flights for the manufacturer and was most recently spotted conducting flights between one and five hours out of Boeing Everett Paine Field. The aircraft is equipped with a water ballast system that is automatically controlled to adjust based on predicted passenger and cargo loads. This allows the engineers sitting in designated areas on the demo aircraft to measure performance data in real-time.
Speaking at a recent media event, at which Simple Flying was present, Boeing’s Brad Till noted how well the aircraft has performed in testing so far:
“As you can see from the list of tests we’ve done, we have really beat it up. Everything’s performed well. As with any test program, as we find issues, we go through our analysis, resolve them, make changes, and then we’ll take it to the the regulator for certification.
Airplane One has frequently been seen making appearances at air shows worldwide in advance of the certification, but the flights are strictly controlled to test engineers and required personnel. Boeing executives directly involved in the program confirmed that even they were not allowed on the flights.
Airplane Two: N779XX
The second plane to roll off the line (MSN 64241) arrived at the end of April 2020. The first two aircraft have been the demo fleet’s workhorses and have done most of the program’s testing so far. According to Till, the certification testing process contains quite a few steps to collect all the information needed for the FAA to begin certification checks:
“A test program begins long before the first flight before the flight test program goes in the air. We start with component testing and then move on to the lab, where we do systems testing and integration testing. Down at Boeing Field, we have an integration lab called Airplane Zero, where we test all the systems together. We did that as a risk mitigation prior to the first flight, and we’ll continue to use that as we get into software builds and hardware changes to the airplane”
The aircraft has been spotted conducting test flights out of Moses Lake and even flew out to Kailua-Kona, Hawaii, earlier this month, beating the average time of a scheduled passenger service by almost an hour.
Airplane Three: N779XY
The next plane to roll off the 777X testbed factory line was MSN 65799, which arrived in August 2020. According to data from ch-aviation, the plane is destined for Lufthansa, where it will bear the registration D-ABTE. The model’s primary role to date has been with load and engine testing. According to Till, this aircraft will do the initial certification tests with the FAA, including cold weather testing, ground effects, modeling testing, and takeoff performance testing, done on the long runway of Edwards Air Force Base.
In July, N779XY performed a series of tests with the FAA onboard. These have included airspeed calibration testing, nautical air miles survey (NAMS) tests in Colorado, and high-altitude tests at Toluca Airport in Mexico. The airport’s elevation of 8,640 feet above sea level is ideal for testing aircraft performance in thinner air.
From there, the aircraft flew to Kailua-Kona (KOA) on the ‘The Big Island’ of Hawai’i. It has remained there throughout August, completing short flights averaging less than half. Following the completion of the testing there, the aircraft is expected to return to Seattle.
Airplane Four: N779XZ
The final airplane, bearing serial number 65800, appears to have been the quietest recently. It first took to the skies on September 20th, 2020, just under four years ago. According to data from Flightradar24, the aircraft last moved the aircraft in April, but it has not recorded a flight since November 2021.
Speaking to reporters earlier this summer, Till confirmed that this airplane will feature a full interior. It will be used for cabin testing and hot and cold weather tests.
In addition to the test aircraft, Boeing has also completed more than 20 777-9 aircraft for paying customers. These remained parked in Washington state and are awaiting final delivery upon certification.
Source: Simple Flying
