C150 Windscreen Break-Up In Flight.

[Flintstone]

Although I gained my PPL in the UK (Clacton) my first CPL/ATPL was from Australia where I emigrated in 1990. The flying school was at Coolangatta on the Gold Coast, Queensland which operated a good mixture of private, GA, training, domestic and international flights. With the CPL out of the way I set about an instructor rating and was paired with a fellow student named Ben. The training weapon of choice was VH-TIA, a C150 Aerobat with a 150hp engine. The extra power and climb prop really helped in lessons requiring trips (back) to altitude such as climbing, stalling, circuits and PFLs. It saved a lot of time over a standard 150/152 and meant more attempts at each manoeuvre per lesson.


(My photos are long lost, found this 'un on t'internet.

We'd got to the stage where we were conducting 'mutuals', treating each other students and practicing demonstrations and patter. Once in the training area to the south of the zone we started the lesson, Steep Turns, at between 8000 and 10,000 feet to avoid thermal turbulence. Ben was in the right hand seat and therefore the 'instructor'. All went well until we heard a loud 'click' and a crack appeared at the top of the windscreen in front of me. We glanced at each other then back at the crack which began to lengthen downward. I executed as gentle a turn as I could and started heading north toward the airport with Ben on the radio copying down the ATIS. He held up his kneeboard to show me the details and as he did so there was another 'click' and a second crack appeared. Interesting.

Within five minutes the first crack had walked from top to bottom, effectively splitting the screen in two. The second crack was advancing at an angle toward the first, making a triangle, and within a few minutes they met. As they did so the cut-out piece of the screen fell inward and only Ben's quick thinking stopped it from hitting me in the face. We now had a couple of problems. With enough power to hold altitude the two remaining windscreen parts vibrated wildly and were in danger of coming adrift. With power reduced to a point where this didn't happen we descended. Thirdly, the propwash made it impossible for me to speak on or hear the radio. Realising this Ben simply pointed at the panel then himself which took care of that although even he had to hunch forward and shield his headset microphone when calling ATC. The terrain beneath us was hilly and covered with trees and banana plantations so putting down there wasn't an option. With Ben repeatedly yelling "Say again! Say again!" into his lap as he availed Radar of our situation I set a northeasterly track for the beach (or as we called it on our NVFR course, the great white runway from God).

We came within glide range of the beach at about 4000 feet and relaxed a little. After some experimentation we found a power setting that, although still had the screen parts shaking more than we'd have liked, resulted in a minimal rate of descent. Ben had produced the VFR chart and was marking our position with crosses in a sort of low-cost-moving-map display as we crawled northward and although we were fully conversant with the area it helped us feel that we had the situation in hand. Through a combination of scribbled notes and hand signals we identified places where we could land if we had to and within a minute or two had a series of red circles drawn between us and the airport. If our situation worsened, something happened at a point where there were rocks on the beach or we were delayed by ATC we had a choice of paddocks in which to alight. I think we even managed a couple of grins.

We were cleared to enter the zone and track direct for runway 32 but asked to delay the latter which would take us over hills and built-up areas. We'd agreed that flap extension might have unforeseen effects on handling so had briefed for a flapless landing and once over the Tweed River set up an oblique base leg. The rest of the approach and landing were uneventful and as we taxied past the tower were treated to a mini-mexican wave by the ATCOs. They had called the flying school as soon as they realised we had a problem yet we were somewhat disappointed by our welcoming commitee which comprised only of Pete, the chief engineer, who after shutdown walked up to the nose of the aircraft and shouted through the hole "That's twelve hundred dollars* you bastards! I've ordered another, it'll be here tomorrow!" before turning and walking away. A couple of days later he presented me with a trophy which he'd made from the broken off piece. Mounted upright on a block of wood it was engraved in pidgin english (he'd spent several years in Papua New Guinea) some of which read 'Two pella masta (two white men), take dis pella ballus (took this aeroplane), no wokkim pinished (not working, finished), na kissim buggerup, plenty buggerup'. That was one of my prize possessions until it was lost in my move back to the UK.

As for the windscreen it was concluded that exposure to UV had caused it to become brittle. Someone seemed to recall hearing a slight crack as they'd leaned on the weather strip at the top of the screen when refuelling an earlier flight that day but seeing no damage discounted it. After that though it was deemed verboten to touch or go anywhere that area during pre-flighting but I would imagine that by the time the new screen became brittle again our story will have been long forgotten.



* A guess. I can't remember how much a new windscreen cost then. I DO know that I was press-ganged into helping Pete fit it.

[dublinpilot]

Thank you for sharing! That's one scenario that I haven't thought through before!