Stuck Throttle
Broken Alternate Air Valve
Pilot reported throttle stuck half way open during flight. Disassembled wye pipe housing the alternate air flapper valve and filter. Discovered most of the flapper valve broken off and lodged in the throttle body, preventing the throttle from closing. Installed new alternate air flapper valve assembly (p/n 15710-002). The failure seems to originate where the radius of the hinge meets the flat surface of the valve on either side of the sandwiched flapper.
