Can an aircraft switch engines?

[Guest MelvinRafi]

I've never actually read about anything like this before, so I'm asking, can this be done?For example, can a 747-400 that's equipped with one brand of engine switch to another brand?:) Melvin Rafi

[Guest]

Usually it is very difficult to do. The main problem is compatibility of the systems connections from the different engines to the airframe. One would have to replace the pylons, bleed air ducts, controls,change the routing of fuel and hydraulic lines etc. The other main obstacle is then the (re)certification of such a major modification.However it has been done. Example Boeing Super27. This is a modified B727-200 where the original JT8D-17 pod engines have been replaced with the larger JT8D-217C or -219 which are from the MD80 series airplanes. The modification required the removal of the old engines, pylons, fuselage formers, associated skins, rerouting of engine control cables, linkages etc. in the rear fuselage area, installation of new formers and rear fuselage bulkheads and strenghthening of the aft fuselage support structure, installation of additional hydraulic components for the new thrust reversers (the original T/R units were pneumatically operated), new pylons and of course the new engines. Since the new engines are much more powerful, but also heavier, a complete revised weight and balance is needed. Some airplanes even need ballast weights in the nose (where the weather radar antenna is housed), to compensate for the extra weight in the tail. Also the center engine Thrust Reverser (T/R) is removed and a special silencer installed instead to comply with Stage 3 noise limits.So it is quite a big deal.- I used to work for a B747 operator who had a single JT9D powered 747-300, while the rest oft the fleet was Rolls Royce RB211 powered. They considered replacing the JT9D engines with RB 211's. But the task would have actually required to change not only the pylons, but also the wings of that airplane since the pylon to wing attachments were different. That proved then to be too much and the whole idea was dropped.The Dee Howard Company in San Antonio, Texas, tried to re-engine the BAC 1-11 with Rolls Royce Tay engines.(from the original Spey engines) As far as I know,they could never get the modification certified and eventually dropped the program.On the other hand Fokker was more successful. They re-engined the F-27 airframe and it became the F-50. Also the F-28, which became the F-70/F-100.Hope this gives you some idea of how complicated this can be.

[Guest]

The F50 and F-70/100 are not "simply" reengined versions of the older aircraft. They are in fact complete redesigns, using different materials and instrumentation as well as new engines.Only the basic shape remained the same.Aircraft have been given different type engines once in a while, but because of all the technical and bureacratic problems involved it is usually cheaper to just sell it and buy another one with the engines you desire.At the moment there is a 707 flying around as a testbed to reengine those aircraft to be compliant to current noise and polution standards. The project works, but the reengining is costly and as most 707s still in service are with 3rd world airlines probably won't get far commercially (the prospective customers aren't likely to have money to afford the program).

[Guest Delta_747]

I think I read somewhere that the 747 uses the same engines as the 767, and that those could be interchanged between aircraft. I don't know if this is fact though.

[Guest]

You are correct. However both the F-50 and the F-70/F-100 still use essentially the same airframes (although with improved materials) as the F-27 and F-28 did respectively. A lot of the avionics and systems had been changed, however. Maybe I oversimplified a bit here.

[Datalink 26]

Hi MelvinI know that the prototype B777-200 PW was eventually sold off to Cathay Pacific a few years ago. They had to re-equip with RR engines and take out the interior test equipment and put in a new cabin.Can't wait for the 747 and 777, keep up the great work :-)

[Guest Delta_747]

I thought the prototype 777-200 was a United Airlines bird with no need of a change. But do you mean the -300 series? I thought on that prototype they were RRs?

[Guest P3_Super_Bee]

The largest Aircraft Reenigne Program:- The USAF C/NKC/RC/KC-135. from the Pratt & Whittney's to CFM's. There are also probably some civlian B707's that have be reengined too, but not for sure.- As mentioned above. The B727 adv reengine program better known as the Super27, is the second largest reengining program. - The DC-8 reengine program is also proably up there in the top 5, probably number 3.- On a side note most if not all P-3A's have been reengined also. Though this undertaking is in no comparision to those listed above.They were out of the factory with T-56-10's and have been swapped over to the T-56-14 which the P-3B and P-3C use. :-outtahttp://publish.hometown.aol.com/p3superb/images/675-2fs.jpg

[Guest MelvinRafi]

Thanks for all the insight on this topic. Yeah, I thought that the first few 777s were delivered to UAL. But take for example when Boeing and Pratt & Whitney were testing the PW4084 during the 777 development period. You'll remember that Boeing took the first 747 (yes, the first one, RA-001) and re-engined one of the engines from the JT9D to the PW4084 in order to create the 777 engine flying test bed. So you had a 747 with three tiny engines alongside one huge turbofan.:) Melvin

[Datalink 26]

It was the very first one of the production line - line no. 001, test reg N7771 and was delivered to CX in Dec 2000. The others after that, 002, 003 etc were for UAL, BA and the other launch customers.

[brucek 38]

I believe you're correct, however if the B767 is ETOPS rated this may have operational limitations. Some airlines I believe do use ETOPS rated engines first on the B767, then when the engine ages they are transferred to their B744 fleet (where an "engine-out" is not quite the same level of importance).Bruce.