Video: Boeing completes 747-8F max energy brake testing

During the month of April, RC501, the first of what is now five 747-8F test aircraft, spent the middle portion of the month at Edwards Air Force base in California performing take off and stability and control evaluations.

Around April 10, say program sources, the aircraft underwent its certification max brake energy test, which saw the freighter – loaded to its maximum takeoff weight of 975,000lbs – slam on its Goodrich-built carbon brakes just before V1 speed transferring all its generated energy into the ground-down disk brakes, heating them to more than 2,500 degrees Fahrenheit (1,400 C). Boeing says the aircraft was able to stop 700ft shorter than first anticipated.
Boeing published its own video (above) of the test on Wednesday.
Boeing 747-8F N5017Q RC521

Certification requirements prohibit emergency services from moving before five minutes after wheel stop to simulate a real-world incident that accounts for dispatch time at an airport. Carbon brakes have made these RTO tests significantly safer over the years as the previous generation of steel brakes would catch fire, posing a greater risk to the crews conducting the tests.
For the sake of comparison, I’ve posted the original 777-200 rejected takeoff test from 1994/95 certification campaign as well. A second interpretation of the same test presents a significantly different tone, naturally attributable to artistic liberty, but the juxtaposition is notable.

6 Responses to Video: Boeing completes 747-8F max energy brake testing

  1. Dave May 5, 2011 at 12:47 pm #

    Why didn’t the 8F have to taxi for 5 minutes like the 777 did?

  2. Scentsy May 5, 2011 at 12:57 pm #

    Absolutely incredible! More people need to see what these aircraft go through to realize how safe they actually are. I remember an L1011 taxiing into my gate with cherry red brakes once and the fuse plugs on one of the wheels did exactly what it was designed for and I had a tire to replace!

  3. iceman May 5, 2011 at 3:17 pm #

    The anouncer was mistaken. The FAA requires 5 minutes from full stop to initial attempt at firefighting. The airplane can be taxiing or parked or whatever.

  4. Paul May 5, 2011 at 3:58 pm #

    Isn’t there also a extra margin added, so it is heavier and at a higher velocity?

  5. 27w9 May 6, 2011 at 4:02 am #

    An RTO is the only flight test condition that deliberately destroys part of the airplane – a full set of wheels, tires and brakes.

    During 1974, long before carbon brakes became available on the 747, Boeing started work to increase the 747-200B’s MTOW from 800,000 to 820,000 lbs [it later was raised to 833,000].

    The first pre-certification attempt at an 820,000 lb RTO [at Edwards AFB] was not successful. The test airplane came to a stop with the smoke and flames coming from the main gear. The USAF fire trucks hesitated, waiting for Boeing’s decision to wait 5 minutes or not. The fire became more intense. Some tires blew before the fuse plugs could melt.

    It was all filmed. The Boeing ground crew can be seen frantically beckoning the fire trucks to the airplane, after which the entire main gear was doused with foam. A few minutes more, who knows what could have happened? A very very close call. The airplane needed a lot of work before a gear-down ferry flight back to Seattle.

    Needless to say, a few brake improvements were required before FAA certification.

  6. Anonimos May 7, 2011 at 12:38 pm #

    http://www.youtube.com/watch?v=UocxPoUUnIQ