Just when I thought I'd seen it all.----or----another item to add to your phase 1 memory items for instantaneous action.

Recently I was ferrying an airplane (not Dairy Queen) from Oregon to Florida. At 17,500 feet I was having difficulty with ailerons when suddenly a hard over aileron occurred. I countered with both hands and all the strength I could muster. It was not enough. I glanced down -and located the pressurization supply air cable. And with one hand-- released momentarily to pull the valve to the out/off position. As pressurization went away the ailerons became controllable although now I had a excessive nose up attitude. As I pulled power off I noticed that elevator trim was now in the full up position and discovered that I had inadvertently (with my two hand approach to the stick) pressed the nose up trim button. (Is this a good reason for a safety switch on the trims?? )

 It took a few moments to sort things out but gradually things got back under control and I descended down to 9500 feet.

Got it figured out? As our IV P's are aging, we have to consider the aging effect on items such as silicone boots in the pressurization system.

While the problem with the ailerons was bad enough, can you imagine what would've happened to a elevator boot blow out which gave full down elevator at 200 kts indicated at 24,000 feet?? Or 10,000 feet.?

A better response to my situation would have been to turn off the door seal allowing it to deflate and releasing pressure on the boot.  Quicker.

  On the airplane in question we have removed the boots and put the new seal system which will prevent this sort of thing from happening again. It would be a good idea to also do this for the elevators also.