AUDIO♫: The devil in the detail

4655
Drifter

How a recreational pilot found himself loaded with fuel without a drop to spare.

Many years ago, I was given the task of delivering a wire-braced, Rotax 503 Drifter from Boonah to Tibooburra. Now you might be thinking, ‘this sounds like an epic adventure in a true, open cockpit, rag-and-tube aircraft’. And you’d be right. Even so, my outback adventure almost came to an abrupt end, about half way in. Let me explain.

This particular model of Drifter had a total fuel capacity of 60 litres. And with a general cruise speed of 50-55 kt (about 100km/hr), its range was somewhat limited. So in order to solve the problem of refuelling at airports that didn’t provide mogas (unleaded petrol) I came up with the plan to carry a 20-litre jerry can safely secured in the back seat of the Drifter (it’s a tandem two-seater). This way I had an effective 80-litre carrying capacity that equated to four hours of safe flying. More than enough to get from one refuelling station (airport) to another.

Now despite the bitterly cold 20-25 kt headwind I experienced from Boonah to Goondiwindi, all was still going to plan, thanks to the additional fuel carried. It was when I arrived at Mungindi airport that my plan went south, as it were. Upon landing and checking my fuel levels, I could see that 20 litres still remained in my tanks.

And with about 45 minutes left to Lightning Ridge (where I’d be resting for the night) at a fuel burn rate of approximately 13 litres per hour, I didn’t think it necessary to untie the full jerry can strapped to the rear seat and top up the tanks for good measure. I hear you gasp, and for good reason!

Setting off from Mungindi to Lightning Ridge I made damn sure I followed my Garmin 12 GPS meticulously in order to maximise my range and get there with a safety margin in hand.

Or so I thought …

I had arranged with a friend in Lightning Ridge to orbit above his house until he came outside to give me a wave which would confirm to me that he would meet me at the airport situated at the southern edge of the town a mile from his house. Everything was on schedule. I flew over his house (at 1000 ft AGL) and circled for a couple of minutes, at which time he came out his front door, and gave me the wave. As I turned the nose towards the airport (about a mile away) the engine began to wind down. Surely not! Had my fuel calculations been wrong? This didn’t matter much. A few seconds later, the engine went silent, much to my horror.

Instinct kicked in, as is often the case in our fight-or-flight response to an emergency. Without hesitation, I adopted the Drifter’s best glide speed of 50 kt and aimed for the nearest section of the airport. It was apparent as I continued my glide approach that I was going to undershoot the airport’s boundary fence by a matter of several metres. And there were large gum trees obstructing my glide path en route to the boundary fence. I was in serious trouble!

Call it sheer luck, or perhaps the whisper of an angel in my ear, but at that precise moment I remembered my earliest flying experiences in gliders. The back-up plan in gliders if you found yourself undershooting the runway threshold by only a small margin, was to pitch the nose down on short final (instead of stretching the glide, as many pilots have tried and failed), build up as much airspeed as you can, and while in ground effect, use your added speed and the reduction in induced drag to create a bit more gliding distance and hopefully pitch up and over the fence between you and the runway. Sure the landing might be heavy, but at least you’d be moving forward. Not stopping abruptly as you either fall out of the sky (stretching the glide), or hitting the fence just short of the field.

So within a few hundred metres of the airport boundary fence I trusted my intuition, pitched the nose down for extra speed, and dived for the ground, trying not to hit one of the many scattered gum trees as I weaved narrowly between them. Once in ground effect, I could feel the aircraft riding on a cushion of air that would hopefully carry me not only to the boundary fence, but over it as well with the excess lift I had generated from additional airspeed and a reduced drag factor.

With trees flickering past me on both sides, and the two-metre fence rapidly approaching from in front, my life certainly did flash before me. Would it all come to a crashing end? It was now or never. I pulled back hard on the control stick in order to raise the nose and balloon over the fence. I was waiting nervously, for the ominous ‘twang’ of the wheels hitting the fence that would follow if my attempt were unsuccessful. But the ‘twang’ never occurred. I had cleared the fence! Next came the landing I knew would not be gentle. In order to clear the fence I had put my Drifter into a low-level stall.

Down pitched the nose steeply from a height of about 10 ft as I held on tightly like a bull rider does for his seven-second ride of terror. Bang! The left wheel was the first to hit the ground hard, buckling as it did so, with its axle snapped in two. Then, as the left wheel strut dug into the soft grass, it acted as an anchor which induced a 180 degree ground loop before sliding to a halt. So there I was: looking straight back at where I’d come from, relieved to be completely unscathed, but shaken nonetheless. My glider training had saved the day, but not my dignity.

Once out of the aircraft, I immediately checked my fuel tanks. To my surprise, seven litres still remained in the lower tank. How could this be? My fuel burn calculations at Mungindi had been correct after all. And yet, here I was. Smeared across the edge of a deserted airport. Upon later investigation it was determined that the fuel intake of this particular Drifter model limited its total ‘usable’ fuel capacity to 53 litres. In other words, seven litres were unusable! As this was my first navigational flight on a Drifter with these unique specifications I was unfamiliar with its pitfalls.

However, in no shape or form does this get me off the hook. Whether it’s your first flight in a particular type of aircraft, or your hundredth, know your aircraft’s specifications off by heart. One day, this knowledge might just save your life. And always remember: a few extra minutes on the ground pre-flighting could mean an extra few decades of your life. God speed.

Note: CASR 92.175 affords private pilots with a degree of flexibility when carrying dangerous goods, such as fuel in jerry cans. Just as this pilot appears to have done, it is important you don’t turn a survivable accident into an unsurvivable one by stowing the jerry cans so they are unlikely to be punctured or crushed.

4 COMMENTS

  1. Eh, what about the 45 min researve that we old GA folk always carried and still do. Legally required or not . I bet some of us add on the 15% IFR requirement through habit even though VFR. So important in the outback

  2. As an Ex AUF pilot and instructor I am disappointed in the way RAA pilots are being taught these days. The author is flying this Drifter like it was a Cessna or Jabiru – if you look at a Google-Maps image of Lightning Ridge you will see there are a thousand places to land a Drifter in the surrounding paddocks – Instead, this RAA pilot got fixated on landing at an airport – at risk to himself and in the process of landing damaged the aircraft.

  3. Peter – I’m no expert, and will take your word on it… but having been to lightning ridge (by car) – the surface of many of those clearings may not be suitable to land an aircraft – lightning ridge is like no other terrain I have ever seen before with piles of rock strewn everywhere (from the opal mining)

  4. One of the first things I was taught when learning to fly a Drifter (during the pre-flight lesson if I recall correctly) was when checking fuel levels, remember the outlet for the lower tank is at the back – and the top tank flows into the bottom tank. Drifters tend to land quite steep with a glide approach all the way from the end of base leg, so if you’re low on fuel you can have that outlet ‘uncovered’ quite easily.
    My new airfield at home is short and surrounded by hills – when I (finally) start flying from here I’ll be arriving high over the top and will always be in glide distance – take-offs will be pilot only, half fuel, with a low level increase to close to VNE before zooming up and turning West (where all the ‘good’ paddocks are).
    What can possibly go wrong?

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