Airborne extract

[Echo Delta]

In the Summer and August issues of FLYER, we're running a fantastic offer where anybody who takes out a new subscription for the magazine before 13 September 2012 will receive a free copy of Airborne, the classic aviation book by acclaimed display pilot Neil Williams.

To give you a taster of Airborne, here's a superb extract from the book looking at the author's extraordinary escape from an airframe failure during an aerobatics practice flight

Wing and a Prayer

For the first time since the inception of the World Aerobatic Championships ten years before,
it was decided to hold this event in the United Kingdom in 1970. The British Team from quite modest beginnings, had grown over this period to a point where we stood a good chance of being highly placed, equipped as we were with two modern aircraft, a two seater Zlin Trener, and a 160 HP single seater Zlin 526 Akrobat. This latter machine was owned by a group of dedicated aerobatic pilots, and we had set ourselves a difficult target in forming the spearhead of the team which was to represent the UK. The airfield chosen for the 6th World Aerobatic Championships was RAF Hullavington, in Wiltshire, and at last we had one of the advantages of the home team, namely the ability to fly over the contest airfield for several months, so as to familiarise ourselves with the local topography. Because Hullavington is in the Lyneham Zone, we had to maintain telephone communication with Lyneham at all times, and this meant that some of the aerobatic team had to man the otherwise disused control tower when flying was taking place. This suited us very well, because of the need to have somebody on the ground to criticise our performances, since errors of as little as two degrees in pitch or roll could lose valuable marks in the contest.
So it was, that on a fine June morning, I took off in the Zlin Akrobat to practice my freestyle sequence. The wind was very light and so did not pose any problem, but I was not quite satisfied with my first two rehearsals. I decided to try once again. This time things were progressing a little better, and I settled down to fly steadily. The aircraft was going beautifully, and I determined to finish the sequence and then land, but as I pulled out of my fifth manoeuvre I ran into trouble. As the aircraft levelled out of the dive there was a loud bang and a severe jolt shook the machine: I was thrown sideways in the cockpit, and at the same instant there was a very loud and peculiar change in the slipstream noise. The problem seemed to be on the left of the aircraft, but when I looked left, everything seemed normal, except that I was being forced against the left side of the cockpit. I throttled back instinctively and looked around, to find that although the left wing was flying straight and level, the rest of the aeroplane was rolling to the left, around the failure point in the left wing root. By this stage the aircraft was beginning to lose height, although I still had some degree of control remaining. I throttled back to reduce air loads but this caused the nose to drop further, and dihedral was by now noticeably increasing, and the roll and yaw to the left were becoming steadily more determined.
I then tried full power in an attempt to get the nose up, but to no avail. By now I was outside the airfield and losing height fast. It was my intention to try and keep the wings as level as possible and to try and hit the ground at as shallow an angle as possible, hopefully in an open space.
It was soon apparent, however, that due to rapid loss of control which I was experiencing, I was not going to make it, and for the first time, the certainty that I was about to be killed came home to me. Control was finally lost at about 300 feet, when the aircraft had turned left through 90° from the original heading, and was banked about 90° to the left (at least the fuselage was). The left wing by now had folded to about 45° and I was treated to the interesting spectacle of the rivets along the top of the main spar opening up like a zip fastener as dihedral increased. When the nose finally dropped I was holding full right aileron, full right rudder, and full power, with a large amount of sideslip. The natural tendency to pull back on the stick only made the situation worse.
In spite of being badly frightened I was still able to think clearly at this stage and I remembered a report I had heard many years ago about a Bulgarian pilot who had had a top wing bolt fail on an early mark of Zlin whilst under negative “g” and that the aircraft had involuntarily flickrolled the right way up, whereupon the wing came back into position, and the aircraft was landed by a very frightened, but alive, pilot. I had guessed by this time that a lower wing bolt had failed and that I was faced with a similar situation, albeit inverted.
It seemed that if positive “g” had saved the Bulgarian, negative “g” might work for me, though at this stage I was so low that I did not have much hope of success. Two things helped me: taking some positive action, no matter how hopeless, was preventing panic, and if it went wrong, at least it would be quick. Anyway there was no time left, and I couldn’t think of anything else to try. I centralised the rudder, rolled left and pushed, still with full throttle. The wing snapped back into p o s i t i o n instantly, with a loud bang which made me even more concerned for the structure. Immediately the negative “g” started to rise and the nose started coming up, but I was too low: the trees ahead filled the windscreen, the throttle was wide open and I pushed the stick as far forward as I dared. For a split second the leaves and branches seemed to reach out at me, then they were gone and I was clear, climbing fast, inverted. Almost before I could appreciate my escape, the engine spluttered and died. Instinctively I eased back on the stick to glide inverted, while I searched frantically for the cause: then I found it – fuel pressure zero. I checked the fuel cock and found it in the “off” position. I had been thrown around in the cockpit at the moment the wing failed, and had probably knocked the cock off then. I selected the reserve fuel and immediately realised that this position would take fuel from the bottom of the gravity tank, which was of course now upside down. I quickly reselected main tank, and after a few coughs the engine picked up and ran at full power again.
By now I was quite low and was initially satisfied to climb straight ahead to 1,000 feet and to return to the airfield. The remainder of the team had been very quick off the mark and had alerted the crash vehicles as soon as they saw the wing starting to move. Meanwhile I throttled back to conserve fuel as the Zlin has a maximum endurance of eight minutes in inverted flight. I retrimmed for inverted flight, and steadied the stick between my knees while I used both hands to tighten my shoulder straps. There was no question of baling out – I had no parachute. It was now that I had to fight against giving way to panic. I could not expect to survive this incident, indeed, at any time I expected the left wing to come off completely. There was an overwhelming temptation to stay airborne for the full eight minutes, rather than attempt a landing earlier, thereby cutting my expected life span in half. At a time like this it is surprising how important an extra few minutes can be. I had to force myself to make the decision to try a landing: the question was, how? I considered using undercarriage or flaps, but rejected both. Flaps were no use to me whilst inverted, and Icould not fly right way up anyway. Also if only one flap extended it would cause an immediate loss of control. The undercarriage required more thought. If I could make an inverted approach with a last minute rollout, I might be able to put the aircraft down on its wheels. However if the gear fully or partially collapsed the aircraft might turn over. Perhaps the biggest argument against this was that the Zlin undercarriage usually locks down with a solid thump. I did not know exactly what damage had occurred and I was concerned in case the strain of lowering the wheels might remove the wing altogether. It was just as well that I left the wheels up, because the failure was not the wing bolt after all, but a fatigue failure in the centre section lower spar boom, inboard of the undercarriage leg attachment.
I also considered four possibilities for
landing, namely inverted ditching, deliberately crashing inverted into trees to take the impact, inverted crash-landing on the airfield or an inverted approach with a last minute rollout for a belly landing.
The last seemed to hold the best chances for survival, but I then decided to experiment to see which way was the best to rollout: if the rate of fold of the wing was sufficiently slow it might have been possible to exercise some control over the proposed landing. A rollout to the left was attempted, whereupon the wing immediately folded again. As gently as possible I eased negative “g” on again, but the wing still came back into position with a solid bang, and as the speed rose in the ensuing dive I could see the whole wing moving slightly. The wing attachments seemed to be getting weaker, so I decided against further experiments: the next attempt would be the real thing at low altitude. Common sense told me that the whole thing was impossible, but I had to try. At least as long as I kept thinking I was able to control panic. Indeed as one close shave followed another there was less of a tendency to panic: it seemed that the mind could only accept so much in the way of fright, and by the time I had flown a wide inverted circuit and positioned the aircraft on finals, I was concentrating so hard that there was no room for fear. I was aiming for the grass, parallel to the main runway: there was no wind to speak of. The temptation to stay in the air until the fuel was exhausted was still strong, but I determined to stick to my decision. If I got it wrong, I would need that fuel to overshoot and try again. I left the canopy on: I didn’t know if the handling would be much affected if I jettisoned it, and also I didn’t want my height judgement affected by slipstream: this approach had to be exactly right. I crossed the boundary of the aerodrome slightly high, at 200 feet, at 180 KM/Hr with the throttle closed. I slowly levelled the aeroplane as low as I dared, at 140 KM/Hr I rolled hard to the right, opening up to full power at the same time, and holding just enough negative “g” in a slight outside barrel roll to keep the wing in place. The axis of the roll was the left wing tip, which left a furrow through the grass for 36 feet, without breaking the plastic cover on the navigation light. By a combination of good judgement, and incredible luck, I had got it right!
As the wings started to level, the nose was down due to the barrel roll, and to ease the impact I pulled back hard on the stick and cut the throttle. The good wing eased the fall, against hard aileron, but the left wing folded straight up, though not before the rate of descent had been slightly reduced. With a bang like the end of the world she hit the ground hard. As the controls went slack I released them and tried to curl up into a ball, knees and feet pulled up and in, and head down protected by arms. The aircraft careered across the grass, the left wing bouncing and flapping like a wounded bird, then with a final jolt, everything stopped. I couldn’t believe it: I was still alive! Then another thought occurred; the petrol tanks had split! To have survived that experience only to burn spurred me into action. I struggled for long seconds to release the double safety harness only to find the canopy jammed! I gave it a resounding blow and it flew open, and as I scrambled out onto the broken wing I felt quite surprised that I was still mobile – I half expected to discover broken bones, but I was only bruised. I looked back at the Zlin, broken, never to fly again, and marvelled at my escape. I sat on the grass and realised how all my senses had been heightened by the drama of the last few minutes: the colour of the grass and sky, the smell of the earth, the song of birds: never before or since has it been so clear. We heard from the manufacturer a couple of weeks later; they sent a telegram which summed it all up in three words – “sorry – congratulations – thanks”! They also let us use their factory demonstrator, a Zlin 526F with 180 HP, which I flew into 5th place in the World Championships. But my real victory had been weeks before, in the old 160 HP Zlin Akrobat, where the prize was – life. ■