show image

Twin troubles: navigating two engines in air

Twin-engined aircraft can be a delight to fly – just as long as you can handle them when an engine fails, writes Ben Griffiths

Two is always better than one, surely? It certainly sounds like it ought to be when it comes to flying light aircraft. And yet the majority of the world’s general aviation fleet remains decidedly single-engined. For recreational flyers this is partly down to the expense of the additional fuel-burn that comes with twice the demand. But these days there are also many more interesting aircraft to sample with just one engine and scant few boasting two powerplants.

It is also no coincidence that most passenger aircraft today sport two engines, certainly for short-haul flights but increasingly on long-haul routes too. There is a certain reassuring feeling to knowing that if one of your engines does stop working you are not immediately going to fall out of the sky – particularly when undertaking extended flights over open water or hostile terrain such as mountains or deserts.

It’s worth noting that most single-engined aircraft will glide perfectly well for some distance, allowing time to carefully select a spot for your reacquaintance with the ground, despite the inevitable outcome if your propeller has stopped spinning.

The crucial difference in flying a light aircraft with two engines rather than one, then, is knowing what to do if you do lose power on one of them. This is because the aerodynamic effects are immediate and profound: essentially the aircraft will want to slew across the sky, yawing and rolling in the direction of the engine which has failed. This effect must be swiftly counteracted using the rudder – pushing hard against the opposite pedal and rolling on some aileron – to reduce or stop it.

It sounds scary and certainly would be, were one engine lost during a flight out over the sea, which is the plan for my flight in the impressive-looking DA42 Twinstar, built by Diamond Aircraft Industries. Based in Austria, the company has been owned since 2017 by Chinese firm Wanfeng Aviation and continues to be one of the world’s leading light aircraft manufacturers.

The test aircraft was operated by CTC Aviation – which has since become part US defence and aerospace group L3 – flying out of Bournemouth Airport. The glorious south coast of England is a fantastic place to go flying with the Isle of Wight, famous Needles rock formation, historic dockyard at Portsmouth and Dorset’s Corfe Castle all within a few minutes’ cruising time. This is also an area steeped in aviation history, from the Battle of Britain to the Schneider Trophy air races and the nearby Supermarine aircraft works, which produced the iconic Spitfire.

The DA42 looks modern, with fuselage tapering back from a bulbous cockpit area and long, streamlined nose. The wings, too, are much longer than the average light aeroplane,
with upwardly swept tips to aid with aerodynamic lift. Two chunky engine nacelles hang below the wings close to the fuselage. Certainly the DA42’s cockpit is a comfortable place to be, with leather seating, intuitive glass cockpit and an unusual forward-folding bubble canopy that affords all-round views as well as an easy way to step into your seat. The control column projects between your legs – no traditional yoke here – and is studded with electronic trim controls. Ahead the instrument panel is dominated by two huge multi-functional displays, showing both moving maps and flight information.

So without further ado, we’re soon airborne and coasting out across the glistening water, our two engines thrumming in perfect harmony as my experienced instructor sets us up for a demonstration of how to handle an engine failure. The required actions were very clear in my mind as he retarded the throttle on our left engine and demonstrated the correct techniques for handling such an emergency. It requires much more rudder pressure than I anticipated, but after overcoming my natural tendency to press quite cautiously on the pedal, we finally begin to notice the nose stops tracking across the horizon and rolling the wings slightly we resume level flight.

At this point in a real emergency, I’d be looking to route directly backto Bournemouth or diverting to the nearest airport. Thankfully, we can simply increase the power on our ‘failed’ engine and continue on our way. A few goes at this and I’m starting to feel comfortable. Flying twins is not that different from the light singles I’m more used to. But the cons of two-engined flying bear consideration.

Besides being thirstier and therefore more expensive, twins do take some criticism. Some experienced people reckon private pilots – who don’t generally fly as many hours as their professional brethren and hence don’t stay as ‘current’ – can make a mess if they lose an engine. They simply don’t react quickly enough with the right mitigating actions. Left unchecked, twin aircraft fly very badly if they lose power on one side and it can be very easy to lose control.

Fortunately, the DA42 is very forgiving, an excellent, stable training platform with four seats which could easily accommodate a family heading for a long-distance flight in reasonable comfort. It appears to be a good step towards more complex types once you’re built up sufficient experience in your log book. There are various popular twins out there, but many are now ageing. The DA42 is much more modern in comparison, hence it is frequently used around the globe to train future airline pilots.

If you think flying twins might be for you, there are a few simple things to bear in mind as you call your local flight school to sign up for training.

The Civil Aviation Authority requires that pilots who have not held a multi-engine piston (single pilot) rating before need to have completed at least 70 hours as pilot-in-command on aeroplanes. You’ll also need to log at least 2.5 hours of dual flight instruction in machines with more than one engine under normal conditions, plus at least 3.5 hours of instruction in engine failure procedures and asymmetric flight techniques.

After that, it’s up to you how you choose to use your new rating. A good starting point would be taking a DA42 up for a few hours to see how it suits your style of flying.