Takes a Licking and Keeps on Ticking
It seems that I’m on a commercial flight almost every week. Once in a while, I’m fortunate to fly on a large, comfortable aircraft and today that’s a 777. We were being propelled forward by two very large, very powerful GE90-115B turbofans. Reliable too. Prior to this class of engine, the FAA required four engines for overseas travel.
Aircraft engine manufacturers such as General Electric, Pratt and Whitney and Rolls Royce allocate a ton of resources to develop and prove out their products and we’re glad. While commercial passengers may loathe the inconvenience of the TSA, they can take safe air travel for granted. Jets are far more reliable than recip engines (what I normally fly when I’m in the left seat). I do have a little time in the L-29 which features a Jet-A sucking turbojet. Newer jet aircraft all have turbofans which use bypass ducts that are quieter and more efficient. Military jets use turbofans too but of the low bypass variety.
Engine qualification involves some exotic tests. It’s noisy and fun to watch. From a distance.
For example: What happens if you throw ¾ of a ton of large hail pellets into the maw of the beast at takeoff thrust? How about 4 1/2 tons of water? GE will also inject both 2.5 and 8 lb. birds into the engine’s composite blades as part of the certification process, All without any impact on the engine’s operation and the fan blades unharmed. If that weren’t enough, technicians planted some C-4 on the fan and detonated it at 2,485 rpm. Even with an engines worst nightmare, the remaining composite blades with titanium leading edges continue to spin. Here’s what it looks like:
The GE90 is huge at over ten feet in diameter and that’s what allows it to produce a record breaking 127,900 pounds of thrust. It’s sufficient to allow the Triple Seven to break the ETOPS record with a five and a half hour flight on one engine.
Even if you don’t get a great seat assignment or a bag of pretzels, there’s comfort in knowing you have an engine that goes the distance.