Patrick Hoyt had with an inflight canopy opening on the fourth flight in his Zenith Aircraft CH 601 a few years ago. He also happened to have two video cameras running and was able to review just what happened. One of the lessons learned was just how hard it can be to see with all that wind blasting you in the face, even with sunglasses.
Pat’s account below, and VIDEO of Canopy Opening:
It was a cold morning, and I was wearing a heavy canvas coat which I had not worn in the aircraft previously, and had a couple additional layers of clothing underneath that. I also had a backpack in the baggage area (during previous flights I had carried it in the passenger seat).
I went through my checklist and verified that the canopy and the secondary latch mechanism were both secured. After I began to taxi out to the runway, I reached into the baggage area to get the backpack. While pulling the backpack out of the baggage area, it caught on the line that secures the secondary canopy latch, disengaging it without me noticing. At that point all that was holding the canopy down was the standard side hooks (65C4-1) that are linked to the latch handle (65-C5-1) that protrudes over the center arm rest between the seats (which normally is all that’s there in the first place).
During the entire time, the back of my arm near the elbow is in contact with the ball (P/N:352-45) on the release tube handle, and I believe it may have been exerting an upward pressure, and that I couldn’t feel it through the heavy coat I was wearing. From the time I applied full throttle on take off, the canopy started gradually lifting as the latches slowly “worked their way loose”. I believe the upward forces of the the air upon the canopy in flight plus the upward forces of my arm on the handle were enough to overpower the spring B-654 which otherwise would hold the handle down.
I first noticed the canopy starting to “ride up” 122 seconds into the flight, at which time I turned back towards the airport. During the next couple of minutes I was on heightened alert and flew very gently as various thoughts went through my mind: The latches have come unhooked, but I have a secondary restraint, so why is the canopy still opening…? Have I left some slack in the line…? Could it be stretching…? Is it slipping…? How far is it going to open…? Was it just going to continue to keep slowly opening…? Or was it going to suddenly “cut loose”…? What if…?
Shortly after turning onto final, the canopy opened entirely. Fortunately I had a straight shot to the runway by then
The total time between the canopy coming fully unlatched and the landing of the aircraft was 24 seconds. The aircraft was controllable, however I don’t know how controllable the aircraft would have been if I’d had to fly it any significant distance, and I don’t know if the aircraft could have maintained altitude or not, as I was already descending to land. Had I been further away from the airport, then the cold temperatures and frostbite/numbing would have become the deciding factor as my ability to control an otherwise flyable aircraft would have become increasingly questionable. Also working in my favor was sunglasses which protected my eyes from the cold wind blast.
I was able to make a safe landing, and after checking out the airplane really good I took it up again for a single flight around the pattern. I was feeling a little rattled, so I landed again and put the airplane away for the day.
The next day I installed an anchor point below the canopy release handle, around which a bungee cord can be stretched to provide more force (than does spring B-654) to hold the handle down and thus hold the latches in place. The existing latch mechanism (including external handle) are still used. Only difference is that now a bit more force is needed to lift the handle to disengage the latches. I flight tested it, and it’s a substantial improvement.
