Date: 201207
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: PA-46 Malibu/Malibu Mirage/Malibu Matrix
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Squat Switch
Component problem: Failed
Reporter organization: Personal
Reporter function: Single Pilot
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Private
Human factors: Communication Breakdown; Distraction; Training / Qualification; Time Pressure
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Everything was perfect with me and my wife sitting in the right seat; reading (clear skies and a 30 KT tailwind) when suddenly there was a loud pop. The pressure differential needle dove backward and cabin altitude red light illuminated. I immediately told Center that we needed to descend now as I put the gear down and started a steep descent. Center immediately said descend to FL210. I said; no; I need lower. (By now we have our oxygen masks in hand but I could not reach the black knob on the tank because it had been installed right behind the left seat.) Eventually my wife turned the black knob on the oxygen tank; but the flow meter indicator window did not confirm that oxygen was flowing. As I dove right though FL210; Center said; OK we are declaring an emergency for you. I deliberately did not confirm or dispute those words because by now we were stable and no longer in an emergency situation. However; our descent rate had been 4;500 FT/minute at an indicated airspeed of 200 KTS in smooth air (VNE is 203K). We had already broken through the latest assigned altitude of 17;000 FT. I finally leveled out at 15;000 FT with oxygen working fine. By now this was definitely not an emergency and I told Center to 'cancel the emergency' and give me vectors to a nearby airport. They gave me the visual to the divert airport. I cranked in direct on the Garmin 530 (with shaky fingers) and we landed without incident. However Tower said to 'call Center after landing. Advise when ready to copy down this phone number.' After arriving at the FBO and taking in a few deep breaths; I called Center on the phone and to my surprise and delight he was pleasant; even congratulatory on the safe outcome but at the same time reminding me of my descent through assigned altitudes and the matter ended. My next call was to my Flight Instructor. He was quick to point out the problem was surely from failure of the squat switch. He pointed out all of the times we covered this situation in Safety Seminars. This event might have been avoided by immediately pulling the pressurization dump breaker. Pressurization could have been restored by cranking the 'rate' knob up and we could have continued on. A couple of weeks later I received a call from the FAA. The caller simply said news of the incident had reached the FAA office and he wanted to know if I had taken steps to correct the pressurization problem. I told him there had been a new squat switch installed and that I was sure the problem was solved. He said thank you and goodbye. However; when I went to pay the bill; the maintenance shop informed me that they had been visited by the FAA and wanted to see exactly what the Mechanic did to fix the pressurization problem. The Mechanic showed the FAA Inspector and that was the end of that; at least as far as I know. In the meantime I found out that the same squat switch failure has occurred at different altitudes in Piper Cheyennes; Navajos and in at least five other PA-46's. In fact; it is so serious that my Flight Instructor; during many trips always pulls the breaker rather than risk the failure while en route. I will not rest easy until I find out why my squat switch failed along with so many others.

Callback: The Reporter stated that this oxygen system is unique to this aircraft because he removed a seat for weight constraints and so also moved the oxygen bottle behind the pilot's seat. He now knows that it is difficult to reach the open valve while attempting to descend rapidly and keep the aircraft's speed under control. As a result he will be moving the bottle's location to an accessible place.



Synopsis: A PA-46 lost pressurization at FL270 after the landing gear squat switch failed. An emergency descent was completed and the flight diverted to a nearby airport for repair.