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- Sep 16, 2019
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Had my boots and air pump fail. Lots of trouble shooting. But learned a lot about the deice system along the way. Thought I would post this here for future owners/mechanics trouble shooting deice systems. The Air pump (vacuum pump) pulls vacuum to power the AI, etc. The positive outflow of this is either ejected overboard, or if FIKI, ejected overboard via a diverting valve. Its a pretty ingenious system with few moving parts. Essentially air from the pump flows into a chamber. Part of that is sent to a solenoid with some venting holes. Activation of the solenoid causes air pressure to build behind a diaphragm that closes off and increases pressure inside a secondary chamber. Increased pressure inside of this chamber opens an outflow valve to the boots. When the solenoid malfunctions, or the diaphragms leak or get old, the air pressure in the chamber doesn't build or build fast enough or to a high enough pressure to open the outlet valve and the boots don't inflate. Below is a diagram. And included a link to bench testing the old valve and the new valve. Unfortunately, these are $$$$. $3k for a new, $2300 for OH. Piper manual mentions a cleaning process but I think that was for an older design.
