by Devesh Agarwal
|A CGI rendition of the Southwest Boeing 737 MAX|
Without a doubt, an aircraft’s engines are one of the most complex parts on an aircraft. After the airframe, the engines are the most expensive item an airline buys, and normally an airline signs separate contracts for the airframe and the engines.
With thousands of rotating parts, and temperatures reaching close of one thousand degrees, engines require regular maintenance. Almost all engine manufacturers like General Electric, Rolls Royce, Pratt and Whitney, CFM, and IAE, offer a concept of ‘fixed total cost of operations’ wherein the airline pays the engine vendor a fixed cost per hour of operation of the engines and the vendor is responsible for maintaining the engines. This concept is better known as “power by the hour”.
Some airlines like US low cost carrier, Southwest Airlines, have extremely large fleets, and find it more economical to have their own maintenance and engineering operations. For Southwest, these engineering centres are based at their major hubs of Dallas, Houston, Phoenix, Chicago, and Atlanta. The centres routinely swap out the CFM56 engines of their all Boeing 737 fleet. Since an aircraft earns money for an airline only when it is flying, airlines always keep spare engines, which are swapped out, allowing the aircraft to be put back in to service quickly. The engine then undergoes repairs and maintenance offline.
The CFM56 engines powering the Boeing 737NG weigh about 2,500kgs each, and even the well experienced technicians at Southwest take between four and seven hours to do a routine engine swap. In the video, observe the synchronism of teamwork that makes this complex task look routine, a task Southwest technicians perform over 154 times a year.