# Is it possible to have two different makes of engine on a single twin-engine aircraft?

Is it possible to have to have two different makes of engines which are generating almost similar thrust for a twin-engine aircraft?

• On one aircraft simultaneously? I read from some type certificate that it is prohibited. Maybe on other type certificate it may be allowed. Maybe you can start there. – vasin1987 Jun 19 '15 at 11:40
• Probably not what you're looking for, but certain piston twin models feature so-called "left-handed" engines, which are really essentially mirror images of the regular models, with the crankshaft spinning in the opposite direction. – habu Jun 19 '15 at 12:04
• Why would you want that? – DeltaLima Jun 19 '15 at 12:21
• just in case, if a company stops production of a certain engine or got bankrupt and there is an essential need to replace one out of two engines of an aircraft, is there any possibility to have some new different engine rather than replacing both and doing all other changes.. I am not sure if this really possible though.. – NitinG Jun 19 '15 at 12:36
• Very similar to this question. – fooot Jun 19 '15 at 14:48

Yes it is possible.

For example :

A Boeing 777-200ER using GE engines . The first engine = GE90-94B and the second engine = GE90-115B .

This is called engine intermixing.

On 737 sometimes The more powerful engine is derated to the same level as the other engine, and we had to do full power takeoffs everytime. As long as the FMC is aware of the intermix, pilots are allowed to use autothrottle.

Here are the sources for your further reading : Source 1 Source 2

Following is another example:

Models with engine intermix already certified

Aircraft models / Engines        Engines allowed

A310-221 / PW JT9D-7R4D1         1 or 2 JT9D-7R4E1
(48000 lb *)                     50000 lb*
(A310-222)

A310-222 / PW JT9D-7R4E1         1 or 2 JT9D-7R4D1
(50000 lb *)                     48000 lb *
(A310-221)

A310-308 / GE CF6-80C2A8         1 or 2 CF6-80C2A2
(57860 lb*)                      52460 lb*
(A310-304)

A300B4-605R / GE CF6-80C2A5      1 or 2 CF6-80C2A3
(60200 lb*)                      58950 lb*
(A300B4-603)

Note (*): Static thrust limit at sea level for takeoff with OAT 30°C.

For these aircraft models, the new engine(s) is (are) installed with no hardware change nor rating change.

• thanks but is it possible that we have one GE make and another Trent/PW make with almost same thrust ?? I think it may not be advisable... – NitinG Jun 19 '15 at 12:45
• Yes, it is allowed. Have a look at Source 2, find "Models with engine intermix already certified" – Victor Juliet Jun 19 '15 at 12:52
• Editted the answer for better understanding – Victor Juliet Jun 19 '15 at 13:00