A little over a week ago, my wife and I were returning to Seattle after a weekend of golf and play in Sun Valley, Idaho.  Everything had gone perfectly on the way there and during our visit.  It’s fun to shoot over the Saw Tooth mountains then drop down into a pretty narrow valley (mountains on each side) where KSUN is located.

We climbed out of KSUN to the south, veered west, then, as we climbed over the mountains, northwest to Seattle.

We leveled at 16.5k and adjusted everything for cruise flight (trim, yaw, RPM, MP, Mixture).  It was pleasant.  Another hour and we would be home, then, suddenly, KABOOMMM!!!!!

From the rushing wind and significantly increased noise, I somehow figured out that we had lost pressurization.  I looked around for obvious causes like a blown out window or something else — expecting the worse and trying to figure out what had happened.  

We were still flying, the engine was strong, and my heart was beating out of my chest.

My wife had the emergency 02 bottle between her legs and we got our masks on pretty fast, as I was descending rapidly and looking for a place to land, not really knowing how air worthy we were at the time, wondering if something had blown off the plane.

I turned toward McCall Municipal, KMYL, just north of our route of flight and called Salt Lake Center, who was helpful with vectors etc., which aligned with my paper map and the “Nearest” button on the Chelton.

We landed uneventfully and phoned SLC to debrief as they had asked us to do.  

On the ground, the plane looked fine.  There was no obvious damage.  I had no idea why we had lost pressurization.

After changing my underwear, I called  a couple of people who assured me we could fly unpressurized without worrying about CO2.

After messing with the plane a few days later, I found the door pressurization seal had blown a  hole in itself.



So at least I now know what needs fixing.

I only have about 150 hours on this bird.  I have no idea why the seal blew.  But when it did, the pressure left the cockpit almost explosively.

One of my early mentors told me not to mess around above 12.5k feet without the O2 bottle out and available and preferably with the mask dangling around your neck,  ready to be deployed.  He said, “some day you will lose pressure.  You have to get your mask on fast.”

We didn’t get the masks on immediately, and it’s amazing how fast you start to feel light headed, even at the relatively “low” altitude of 16.5k.  It’s dangerous.

So, note to self:  Flight plan and prepare for emergencies, get a weather briefing,  have too much fuel, preflight the plane carefully, follow the checklist, and if anything happens, aviate, aviate, aviate, then navigate and communicate if able.  Most important lesson for this one:  Have the emergency O2 mask around your neck and ready to go any time you are above 12.5k.  Period.   

Hopefully, you’ll never have to use it.

John Hafen
IVP (not currently pressurized so scratch the P part)  N413AJ — 150 hours.