PA-46 Malibu/Malibu Mirage/Malibu Matrix
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 40; Flight Crew Total 2850; Flight Crew Type 545
While cruising at FL250; the aircraft experienced a total cabin pressurization loss. I immediately attempted to define the problem; what happened; and consider any available solution. I immediately attempted to place my face mask into operation. I was having an issue with turning on the O2 supply and decided to start an autopilot descent. I thought that if I encountered a loss of consciousness; the aircraft would level at a safe altitude; the aircraft would still be in control until I regained consciousness. After checking to make sure there was no damage and that the plane was safe to operate. I proceeded to review the emergency checklist for the problem. I reset the system numerous times but to no avail. I attempted to contact ATC but forgot to change over the mike switch from boom to mask. As soon as I had gotten O2 flow; I then proceed to change the mask mic over to mask. I contacted ATC to let them know of my situation and they cleared me to 11;000 feet. The Controller indicated that the Supervisor had cleared the way for me and they were most helpful. Once everything returned to normal; pressurization was restored and I was cleared to higher altitudes. My final was FL230. The rest of the flight was uneventful.After a thorough review of the events; I can say that I did not know how long the entire situation took to get my clearance to 11;000 feet. While I would anticipate 4-5 minutes before loss of consciousness; I completely lost track of the time of the event. My aircraft pressurization system was recently checked; door gasket replaced and passed a thorough check out and pressurization test. This situation occurred because I believe that the main squat switch on the left main gear had gotten moisture in it and after some time at FL250; it froze and therefore shorted out. This switch controls the outflow valve and once it thaws out; everything returns to normal.  This switch will be replaced as soon as possible. Regarding the interaction with ATC; I cannot say enough. They were professional; thoughtful; and assisted me in whatever I requested. They followed up to make sure everything was good to go. I have spoken to my flight instructor about the incident and he felt that it was handled in an acceptable manner. Unlike most accidents where there is a chain of events; this came out of nowhere and demanded immediate attention and resolution.
Piper 46 pilot reporter a total loss of cabin pressurization while at FL250. Pilot reported having issues with the O2 mask and elected for an autopilot descent to 11;000 feet and pressurization was restored.