Keeping in mind that a plane can fly with different engine models (e.g. for test purposes), has an error ever happened during normal operations that led to the wrong engine being mounted? Is some kind of calibration or check necessary before flight to ensure that the engines are the correct ones?

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    $\begingroup$ Is the included video meant to be an example of a different engine being mounted? It's not as simple as swapping engines, there's a lot more modification that has to be done. $\endgroup$
    – fooot
    Apr 14, 2016 at 19:28
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    $\begingroup$ I would say no, its not possible. Maintenance is tracked very carefully by serial number. If they did something like this it would mean the correct serial numbered engine for another aircraft was missing. $\endgroup$
    – Ron Beyer
    Apr 14, 2016 at 20:08
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    $\begingroup$ Excluding test engines, most airliners that have different engine options also have different pylons for each engine option (the 787 was intended to have a common pylon for both engine options, but this was quietly dropped as a concept, as was the ability to quickly convert from one option to the other), so you would have to bodge a lot of stuff to hang a different engine off of a pylon meant for something else... $\endgroup$
    – Moo
    Apr 14, 2016 at 20:46
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    $\begingroup$ You imagine they have got a bunch of engines sitting around in the corner of a hanger? $\endgroup$
    – kevin
    Apr 15, 2016 at 8:11
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    $\begingroup$ The closest thing I can think of is the Air Transat 236 flight that was caused by a different engine being mounted. However, the issue was that they used an incorrect pump, the engine itself was fine. $\endgroup$
    – Pondlife
    Jul 19, 2016 at 12:36

1 Answer 1


January 2016: a "wrong" or non-functioning engine was mounted onto a Qantas 747. QF63 departed from Sydney to Johannesburg with a 5th engine.

The 747 is capable of carrying these kind of loads through anchor points on each of their wings.

enter image description here

Disclaimer: this wasn't by mistake, it was intended to get the "5th" engine to Johannesburg ASAP, to be fitted onto another aircraft.

As for the possibility of mounting an incorrect engine on an airplane by accident, it's very unlikely (impossible really). Jet engines are designed exclusively with the aircraft in mind. Further, jet engines are expensive you would make certain you order the correct engine for the corresponding aircraft. Aviation mechanics also receive sufficient training and the an engine replacement process isn't a one man job. It circulates through a group of individuals prior to actually making a purchase or deciding to fit a new engine.

Besides, even in the case where some unqualified individuals were to attempt mounting an incorrect engine, it wouldn't work. First, they would easily be able to distinguish the existing engines from the replacement. Second, the mounting the engine in the place wouldn't work, the mount points would be of a different shape and would consist of bolts and screws in different locations.

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    $\begingroup$ The 5th pod stuff is irrelevant to the question $\endgroup$
    – Steve Kuo
    May 11, 2017 at 15:30
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    $\begingroup$ That's a bit harsh. It's a great answer that covers all the bases and gives us the "closest case". $\endgroup$
    – Fattie
    Aug 16, 2018 at 4:26
  • $\begingroup$ Is there a mount point under each wing, or is there only the 5th one? $\endgroup$
    – T.J.L.
    Jan 15, 2020 at 21:35

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