1. The idea is supposed to be “well, modern twin-engined airliners still have plenty of power if they lose one engine,” but that sort of neglects the problem of “both engines were probably worked on by the same moron.”

  2. Have you seen this video?


    The engine appears to be running….. Ok.. actually probably the outer fan is turning on its own driven by the airspeed. At least what remains of the engine is still attached to the wing so likely not a major failure of the rotating Turbine. More likely a failure of some of the Blades but not enough to cause a major imbalance leading to catastrophic failure.

    Engine are at max thrust during takeoff and don’t work as well in the ticker air at low altitudes, So failure is more likely on takeoff that cruise altitudes .

    But that does happen https://www.youtube.com/watch?v=PrbxtVPY0rE

    Note the calm manner of both the air traffic controller and likely the co-pilot doing the Mayday Call. No panic or urgency in the voices ……. The Training kicks in and all sounds like this happens all the time.

    …… and the steady hand of whoever took the video of the engine.

    1. It’s not often anyone can get video like this. Thanks for posting it.

      I am no expert on jet engines, but obviously some failed turbine blades punched holes out the sides of the engines, and either the blades or escaping flames destroyed the outer casing. Modern jet engines have a little armor around there to deflect those broken blades from going through the wings or fuselage, but it cannot be too heavy – and ricocheting broken blades back into the turbine just makes more broken blades, so they would try to design it to let the fragments exit in a safer direction. I don’t know if the red glow is residual fuel burning or just red-hot metal. It takes high temperatures to efficiently extract power in any heat engine, so I expect the first turbine stage(s) would be red-to-white-hot in normal operation and for for many minutes after shutoff.

      The flames are not coming out the holes in the side (although they might have been a little earlier), so the inner compressor is no longer pressurizing the combustion chamber. That also means the turbine stages are not getting pressure to spin whatever is left of the turbine. It could have got there through total disintegration of the turbine, or through a few blades breaking and going out the sides, pressure leaking out the holes, and then the compressor power and turbine pressure would wind down together to zero.

      The truly scary part of an event like this is not losing the engine; twin jets are built to fly and land on one engine. It’s that the fragments of the engine could come slicing through the fuselage, tear up the wing or tail, or cut control lines. If the engine was closer to the wing, the heat might also weaken the wing spars, but I guess that was one reason nearly all non-military jets have engine pods on pylons rather than engines built into the wings. (See the B-36 for an example of both mountings: 6 piston engines merged into the underside of the wings in a compromise between aerodynamics and access for maintenance, and 4 jets on pylons. You can tell which technology was new and not trusted.)

  3. As part of earning it’s FAA Airworthiness Certificate, any of the twin engine jet airlines have to pass some pretty demanding tests. Which include a takeoff at maximum gross weight from that selfsame Denver airport, (or some remote Utah strip of similar altitude) on ONE engine. A Boeing 777 can fly it’s entire FAA Certificated flight envelope on one engine. Actually, any of the twin jet commercial airliners can do so, including the short-hop commuter jets.

    Another fun test you can view on YouTube, is the 777 also at maximum gross weight, and performing an “aborted” takeoff at V-1 speed, and coming to a full stop on wheel brakes alone, with no engine reverse thrusting. And then remain stationary on the runway for five additional minutes without the red-hot brakes setting the rest of the aircraft on fire. (the brakes ARE on fire, and a couple tires blow in that video, but flame doesn’t spread.)

    Point being, there are HUGE design reserves built into modern airliners. Doesn’t make ’em crash proof, but does make such exceedingly rare.

    That said, the FIRE on that shattered 777 engine is some scary shit. It would be just as scary on a four-engine 747 though. Fire on *any* airplane is something you just don’t WANT, period!

    Airbus made a couple of four engine airliners, including the A-380. Those are already in the retirement pipeline, with several airframes now baking in desert aircraft boneyards. The Boeing 747 line has had only freighter orders now, for some time. The four-engine paradigm has pretty much run it’s commercial course, with only the .mil and .gov planning to operate such (or the eight engine B-52), into the future. Economics of the big twin jets have completely realigned the commercial airliner marketplace.

    Might not the MD-11 and L-1011 triple jets have been a bit of a Sweet Spot for widebody design?

    Pity a system wasn’t designed to make their center-engines be able to be shut down and “faired off” in flight for streamlining at altitude and speed. Third engine for takeoff and reserve power at landing.. and emergencies, and un-necessary at cruise.

    Sunk New Dawn
    Galveston, TX

    1. The tri-jets were a compromise designed when the airlines wanted to move to twin-jets, but the FAA and other national regulators did not trust twin-jets for long flights over water. Originally 4-engine planes were required over anything bigger than the Great Lakes to give a safe flight on 3 engines or a chance of making it on just 2. Hence designs like the Constellation (4 piston engines) and 707 (4 jets).

      Once there was a long enough track record for jet engines (late 1960’s), the regulators decided three engines were safe enough for ocean crossings. (That is, the chance of two independent engine failures was deemed a lot less than the chance of a fuel leak, fueling error, or same bad part or mechanics error taking out _all_ the engines no matter how many there were. Wikipedia has an impressively long list of all-engine failures in commercial aircraft, and almost none were due to two or more independent engine breakdowns.) Three bigger engines cost less, required fewer maintenance hours, and burned a little less fuel than 4 engines. With the 1970 engine technology, 3 jets limited them to smaller aircraft than the 4-engine 747, designed at about the same time.

      But the 747 and other 4-engine widebodies turned out to be too big for most passenger operations. They were restricted to large airports (although many airports were eventually upgraded for them). It took too long to load about 400 passengers. And there were only a few routes that could keep these big airliners full without unduly cutting the schedules. So the 747, which was designed for passengers or freight thanks to a cautious Boeing management, wound up mostly in freight operations between major shipping centers, where the weight and volume capacity could be used and efficient marshalling of the pallets could keep the turnaround time low. Airbus didn’t fare as well because their A340 was not a good freight carrier, and McDonnell Douglas eventually dropped their attempt to design a rival to the 747 (the MD12) and merged with Boeing.

      So except for some air freight, the tri-jets turned out to be the more practical size. But that third jet in the tail is a headache for mechanics to reach…

      Now there are engines big enough that just 2 will propel that size of aircraft and they save cost, maintenance, and fuel over the tri-jets. The FAA, etc., have decided that a modern twin-jet can be built to be safe enough to go where it’s a 180 minute flight on one engine to a landing, and there are enough commercial airports and emergency landing strips that this covers something like 90% of the earth. (Look up ETOPS.) In particular, it allows a great circle flight from most of the US to most of Europe, so the ETOPS-180 qualified twinjets are now optimal for the majority of trans-Atlantic flights.

      Crossing the Pacific might still require a little zigzag in the route to stay within the ETOPS-180 limits, but I expect the airlines will consider the savings from owning a fleet of one kind of twin-jets to be worth adding a few minutes to a few routes. The FAA now will consider extending ETOPS to 240 or even 330 minutes, although each approval is case-by-case and only covers one combination of aircraft, operator, and route; a good history of ETOPS-180 operations is needed to apply for the extended lengths.

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