malabo, if you have a rough 1/rev in a 139, you need to track and balance.
I've never looked after a 139 that was higher than 0.08 ips lateral or vertical.
If you're talking a rough 5/rev, play with the tuning weights under the floor. Don't go by the book, get it close using book values and then play with it each flight to optimise it for your cabin and aircraft configuration.
Or, just go buy the MVA. You won't be disappointed!
The 139 should only be rough when getting close to Vne or during translational. In cruise it should be nice and smooth.
Nice photos of the cockpit John, but I do note on the Fuel page that there is a corss feed interconnect in the tank. It is not at the bottom, but looks like it is placed about the same as it is in the 139, so if you lose an engine in the 169 you will have some fuel that you can't get out, but most will transfer across.
An old brochure I just dug up confirmed the interconnect. It says 200 liters will fill into the left tank before it reaches the interconnect. So if you have an engine out, there will be a maximum of 200 liters that you can't use. About the same as the 139 if you have a boost pump fail.
Now how to get the training course and not have to pay for it.......