Boeing details role of fourth 747-8F flight test aircraft

With upcoming addition of RC503, the fourth flight test 747-8F, to the flight test campaign, Boeing has offered some details about what the aircraft has ahead of it:

We are planning to conduct some engineering tests on another airplane. The airplane would conduct the non-instrumented or minimally-instrumented tests, such as HIRF and Water Spray Cert. Conducting some engineering tests on another 747-8 Freighter enables the program to gain efficiencies in flight test. It allows the program to remove the non-instrumented or minimally-instrumented work statement from the three core flight-test airplanes.

Program sources add that the water spray certification testing is planned to take place at Glasgow, Montana. Additional tests will include wake vortex and high altitude landing and takeoff performance at El Alto International Airport in La Paz, Bolivia. El Alto’s main concrete runway sits 202ft higher above sea level than the 13,123ft runway is long. RC503, the second production 747-8F is currently slated to make its first flight at the end of June and join flight testing about a month later. 

Meanwhile, RC501 remains at Moses Lake where the aircraft is in the next phase of stability and control testing, as the handling of the aircraft is evaluated at different weights and centers of gravity. 

As of late May, three 747-8F aircraft had completed around 300h of testing. On May 21, Boeing Commercial Airplanes CEO Jim Albaugh had expected expanded Type Inspection Authorization to be received in “in the next few days“, however that target appears to have slid.

RC521, which is visiting Victorville at the moment, is in maintenance for the next several days after a towing incident on the evening of May 31 that saw the number four engine hit a tug causing damage to the cowl and engine inlet. The GEnx-2B engine was not damaged and no one was hurt during the incident. Interestingly, Boeing revealed this incident using Twitter rather than other more direct means, and is a good illustration on how far the company has come in using social media.

Sources say the repairs on the engine nacelle should wrap up tomorrow, with the aircraft returning to flight testing on Saturday. Upcoming flights will see RC521 undergoing nautical air miles (NAMS) testing and engine deterioration tests to measure the fuel performance of the aircraft’s four engines, as well as establish the baseline for long term increases in fuel flow as the engines age.

RC522 is in the midst of ground testing in Palmdale, where test crews are evaluating the smoke penetration of the cargo hold of the 747-8F.

Boeing has completed the fix on the outboard landing gear doors that caused the buffet on the inboard flaps while at the 30 setting. The most noticeable change puts the lower panel door more in line with the upper panel, which was once rigged at a 45 degree angle similar to the 747 variants that preceded it. The modifications also include vortilons on the inboard flap as well as a bullnose design on the leading edge of the upper half of the outboard landing gear door.