A few short minutes ago I was up among those cirrus clouds at 30,000ft.
I began a shallow dive, but realized too late that the extreme cold and the moisture that had condensed on the way up had caused my propeller pitch change mechanism to ice up. These first generation De Havilland constant speed units are prone to that if you don't exercise the engine speed control periodically at high altitude. I hadn't. The engine rapidly over-sped, and so did the aircraft, with each of these two factors only worsening the other. Both engine RPM and airspeed were soon off the scale. I entered compressibility about the same time my engine began a rapid unscheduled self-disassembly, which brought my propeller to a sudden and complete stop with a screech and a loud bang and sprayed oil all over the windshield. Compressibility was causing the dive to steepen uncontrollably, and I was still accelerating. Too fast to get the canopy open (this wasn't one of the improved design that can be jettisoned) and even if I did, I'd be pinned to the canopy frame by the screaming 500 mph+ blast of air. No choice but to stay with her and hope the denser air at low altitude would slow me down and make my elevator effective in time. Slowly, the compressibility effects began to diminish, but not quickly enough. As a last resort, I deployed the flaps, knowing full well they'd quickly be ripped from my wings at this speed, but hoping they would at least help me decelerate for a moment, and the drag from whatever wreckage was left behind might help further. It worked, and I was able to pull my much-abused airplane out of the dive, with a couple thousand feet to spare. I put the flap switch back up to prevent the now torn-open pneumatic lines to the flaps from draining all of what remained of my pneumatic pressure. With no engine to drive the compressor, I would only have what was in the reservoir, and if I was lucky enough to be able to make a wheels-down landing, I'd need that for the brakes.
Now slowed down, I was able to open the canopy to see around the oil, and see what my options were. I soon found West Malling within easy gliding distance, so I opted not to bail. Now to get the undercarriage down. My engine-driven hydraulic pump was obviously not going to do me any good, so I followed the emergency procedure: set the undercarriage lever to the DOWN position, and then (and only then) push the red emergency undercarriage extension lever forward and down. I could hear the hiss of the compressed air pushing the undercarriage down, and soon saw the green DOWN indicator illuminate, and there was a red indicator pin sticking out of each wing. I was home free now. Time to secure the aircraft for a potential crash landing if something didn't go to plan - fuel cocks off, ignition off, cockpit door to the half-cocked position to keep the canopy from slamming shut and jamming in the event of a rapid deceleration. The glide was progressing beautifully, my landing run was now aligned with the windsock, and I had a nice light touchdown and a slow roll to a stop in the middle of the grass of the airfield, using the last gasps of my pneumatic pressure on the brakes.
Who says non-combat flights are always boring!
