I'd love to hear what you come up with, mate!

Don't confuse BAE (Or Hawker Sydley) press releases to the industry and advertisement claims against real reasons.

Budget. Budget. Budget.

When the aircraft was fist designed in the late 60's - 70's, the choice of engines that had been through the (lengthy and expensive) certification process was limited.

The Texxtron/Lycoming (then) engine variant had been in helios in vietnam and was based on a older core engine from a tank (although Honeywell think it was a completely different engine).

I don't know why people are mentioning "Hot and High", the ALF 502 is very asthmatic with limited turbine margin on a good day and the later 507 on the RJ is not much better.

I've worked on 146's/Rj's on and off for 12 years and the above is just stuff I've picked up on various courses over the years.

The RJX should have been designed with 2 larger motors IMO, 4 Donkeys on a regional jet did scare people who were awaiting the Embraer 170/190 family coming off the drawing board.

The 502's in the first 146's were really unreliable dogs,it was a good job there were four of them(& a good job they're easy to change).
When Allied Signal acquired Textron Lycoming they spent a small fortune on increasing the reliability & these days they're not too bad.
The 507's in the RJ's have the increased temp margin but are still prone to the occasional uncontained failure.

Easy, the wings weren't long enough for 6.

Ayuk ayuk. :D