Hello all: I just recently purchased a Navion and have noticed an odd problem with the flaps -- they won't hold position when the engine is at idle and will droop to full flaps. Where this has come up is here: I have been using 15 degrees of flaps on takeoff and when I'm waiting at the hold short line the engine will be set at idle and I will notice the flaps have then sunk to full. I can prevent the problem by maintaining at least 1000 rpm, so I am guessing that there is something, perhaps a pressure seal, in the system that doesn't hold with lower rpm (and therefore lower hydraulic pressure).

Anyone ever seen this problem?

Thanks, David Brody

I had the same issue on my bird and found that although I had the center "neutral" notch in the panel, I had the original black North American MCV. That valve is actually only an up/down valve. I found a green Gladin MCV and sent it to Ron Judy to be rebuilt. It has the additional poppets in it to truly stop and hold any position.

If you ignore that the flaps have drooped to full down position, they will normally return to the preset half flap position as you increase to full power on the take-off roll.