From L4P N6XE;

 

Today while flying over the Sierras at FL 210 we had a big pop and the cabin altitude was pegged in the wrong direction. Big noise and I pushed the nose over hard put the O2 mask on with my right hand and told my wife to turn on the bottle while I just watched the IAS and ran it up to 245. I may have reduced MP but don't remember doing that but later when level it was at 27 in. I guess it took a little over ONE minute to get to 160. I called ATC that I had an emergency and descending, I told them what the problem was but they couldn't understand me. I have Boise headsets on and while it was noisy it wasn't that bad. Another aircraft heard me and relayed my pressurization loss message. They cleared me and immediately gave me a heading to the nearest airport. It was perfectly clear so I could see fine except for the biggest mountain top right strait ahead, which happened to be the tallest peak that I would cross in the Sierras East of Fresno, CA. The controller calmly said that the MEA there was 17K and if I could see, than going down to 16K would be fine. I leveled at 16k and had already determined that the engine was running fine and just needed some time to investigate. Getting back on course and on the TruTrak altitude hold so I could look around. ATC asked me to call  when I had a chance. He asked how many people on board and fuel situation. The CFS EFIS has all that in front of you so I told him. After determining that the Windows were fine I noticed the door seal was deflated and the Switch in the door sill was in the OFF position. I had already Dumped the Pressure Switch so I flipped the Door Seal switch to ON and it worked fine. My switch sticks up thru the leather upholstery which is padded. I had never noticed that when in the ON position it pushes on the leather and pad. Guess I'll fix that now. Note that when the seal is off the noise from the door gap is about 10 inches from my microphone and that is why ATC couldn't hear me even though I could hear them fine and I thought the noise wasn't that bad.

Nothing like a real world Training class. My wife didn't hear me say Open the Bottle, so now she knows what to do without instructions. That is the only reason I ware the Mask around my neck and the only reason to have the bottle on board. Need to relocate it for better on/off access, it's under the pilot seat front with the connections and control under the emergency gear down handle.

If I would have been at FL 250 it could have taken another minute to descend.

The only turbulence on the whole 2:15 flight was while I was descending at Max speed right at the top of the mountain peak we hit a bad series of jolts, banging my head on the door above the pilots head. So getting my ears popped, banged on the head and an otherwise normal flight form San Jose, CA. to Sedona, AZ.

It's going to be hard finding someone to ride with me when this gets out. We were just getting out something to eat and these things have to happen just 2 miles before the tallest peak. However, I know the tallest is 14K so going down to 15K will give you about a 30 min. time of useful consciousness vs One min. at FL250.

Didn't even looks at the Mach number in the descent.