Rolls Royce/General Electric Engines

brenn7475

Just wondering why are some some Airbus/Boeings fitted with either Rolls Royce/General Electric.

L1011

Airlines have preferred engine manufacturers for multiple reasons - fleet commonality (across airframe vendors in some cases, e.g. having CFM56s on an A320 due to also having 737NGs), national pride, past experience, etc.

Other times its down to performance characteristics for specific uses of the same type of craft. Also, having multiple engine options can drive down the price of the engines due to competition.

brenn7475

Nice one thanks for the info.....

Delta Kilo

MYOB wrote: »

Airlines have preferred engine manufacturers for multiple reasons - fleet commonality (across airframe vendors in some cases, e.g. having CFM56s on an A320 due to also having 737NGs), national pride, past experience, etc.

Your kind of half right with this bit. There is 0 compatibility between the CFM56-5B on the A320 or the CFM56-7B on the Boeing 737. Entirely different thrust ratings and mounting points for a start. Not many airlines perform their own engine maintenance either, usually done out of house.

Anyway, In the preliminary design of an aircraft when the manufacturer has calculated the thrust requirement, a tender will be issued to many different manufacturers to develop an engine to meet this requirement. The engine manufacturers will each bid using their own reasons as to why theirs should be chosen. There are many factors; cost, manufacturing capability of the engine maker (for instance if Airbus plan to manufacture 200 of the A320 a year, the engine manufacturer has to be able to output more than 400 engines a year).

So it’s the aircraft manufacturer that will decide, but they will be keeping their customer, the airline, in mind when making the decision too. Important things nowadays are operating costs, Life Limited Parts etc. Manufacturers are trying to make engines with synchronised LLPs that have the same cycle number before they have to be replaced. This cuts down the number of Shop Visits the engine has. A shop visit could cost the airline in excess of $2m although usually about half of this if it is an LLP only Shop Visit, still a significant cost though.

It has happened before where two manufacturers won a tender meaning the airline had options. For example, the A320 with the IAE V2500 and the CFM56-5A. Initially the CFM engine was seen as weaker and the IAE was more popular amongst operators so CFM modified the engine and created the 5B that is the most popular on the A320 today.

So in other words, the Airline dont give two hoots about having the same engine fleet across their range of aircraft, they just care about the best one to operate over its lifetime. All they can hope is the aircraft manufacturer has chosen the best one!

EDIT: Just to add to that actually, it also depends on the size of the plane, some manufacturers specialise in specific sizes of engines. CFM mainly builds smaller ones used on narrow bodies like the 737 whereas Rolls Royce would traditionally manufacture larger engines such as the Trent 900 on the A380. GE (part owner of CFM with Snecma of France) also make big engines llike the GE90 used on the B777.

smurfjed

When we looked at the A330, It came with 3 engine options, GE, PW and RR. As the RR engine has a higher engine thrust flat rating point than the other two, it became apparent that it would deliver greater performance than the other two. The PW actually offered the lowest fuel burn, but as the RR could achieve max thrust up until ISA+22 degrees, it was a better choice for this part of the world.

As for the A320, from a purely performance point of view, the IAE engine offered us 2 extra passengers on the A320 or 7 on the A321 for certain routes. For other reasons we picked the CFM engine

smurfjed.