I've only had my Yalmaha a week or so now, but I've already found plenty of bugs with it.
If you zone indoors when you are in the plane it changes to a red icon. Now if you die inside it is still a red icon when you're back outside at the reclaim.
If you equip the yalm sitting down you cannot take off, and move around at your normal runspeed.
If you crash whilst in the yalm you cannot change altitude when you log in, you can only move around in a level plane at that altitude. Taking the plane off has no effect, you'll still be inside it even though it's now in your inventory. Relogging solves this problem.
On certain mission areas in newland desert you exit into a lake. As with sitting down it will not let you take off, and the nose moves side to side like you're in a kodiak. You have to get to land and re-equip the plane again to solve this.