Choosing a Light Sport Aircraft (LSA) – 4 – secondary safety

Cockpit safetyNext, secondary safety. This ranges from the simple – eg how many bits stick out in the cabin to injure you during anything, from just getting into the aircraft, to a full-blown crash – to the complex – how the airframe will protect you (or not) if you hit something or end up inverted in a field.

 

 

At a basic level, have a look at:

– how close are your legs to the instrument panel and other parts of the airframe?
– How close is your head to the canopy or roof? Sudden turbulence could potentially give you a nasty bump!
– How the seatbelt is fixed to the airframe and whether it has one or two shoulder straps (or even a crotch strap – usually only in aerobatic aircraft).
– Whether you can easily pinch your fingers under levers and other controls. Could be a dangerous distraction if it happens at a crucial time, like taking off or landing.
– Whether there’s suitable padding in likely areas of head or knee contact.
– Could you sit there for 2-3 hours without aches, pains and cramps?

At the next level, consider:
– how easy is it to exit the aircraft in an emergency? For example, if there’s an engine fire on the ground.
– Could you get out if the aircraft was inverted on the ground?
– Is there plenty of room to move in the cabin?

Small aeroplane big manIn particular:
– Can the controls be moved fully and freely to their limits without having to move your (or your passenger’s) legs out of the way?
– Can you push full rudder deflection? Both left and right?
– Can you see out properly? How difficult is it to see the runway in front when you’re on the ground?
– Do you have to duck to see under (or over) the wing while flying? You’ll soon get a crick in the neck if if it’s a pain to look and you might do it less often than you should.
– Is it easy to knock the controls inadvertently – particularly the throttle and the elevator and/or aileron trim?
– Does the aircraft have an isolating switch to cut all electrical power in an emergency?
– Is there a park brake to facilitate engine warm up and ignition checks? In some aircraft it is virtually impossible to hold the brakes on, hold the flight controls, use the throttle and check the ignition all at the same time.

Safety cageFinally – and usually more difficult – try to find out:
– Is there a safety cage or roll-over hoop round the cabin ? This will help protect you and your passenger in an impact and also help keep the doors (or canopy) from jamming shut, trapping you inside.
– What is the safety record of the aircraft? What percentage have injured people or worse?
– Can it be fitted with a ballistic rescue parachute?

 

The last word about secondary safety concerns the material the airframe is built from. There are three main types – metal, wood and composite.

Metal wing bendMetal is well known to have excellent impact absorbing qualities; initially it bends rather than breaks and structures can be designed to reduce the G-forces acting during a crash. A common reaction from people who’ve experienced an accident in a metal airframe aircraft is ‘it all seemed so gentle, I just couldn’t believe the aircraft was a write off when I got out and looked at it’. That’s because the airframe did its job. However, if there’s corrosion in the airframe, it may not do its protecting job properly.

Wooden wingWood is used much less in LSAs nowadays, although at least one of the most famous World War Two aircraft – the De Havilland Mosquito – had a wooden airframe. A well designed and built wooden aircraft should have good impact absorption although in some higher energy crashes, wood will break suddenly as it doesn’t bend as much as metal. It also depends how much of the airframe is glued, pegged or screwed together – believe it or not, a well-glued wooden airframe is stronger than one screwed together.

CComposite wing damageomposites are used extensively in LSAs. Some manufacturers will tell you their aircraft are ‘carbon fibre’ but in most cases – because of the sheer expense – this is used very sparingly only in high-stress areas. Most composite aircraft are mainly or wholly some sort of glass-fibre. As boat builders will tell you, getting consistent results when manufacturing with glass-fibre is a notoriously difficult process. As a result, the empty weights of the same model of LSA can vary substantially (see Choosing a Light Sport Aircraft (LSA) – 1 – what about weight?). Also, to ensure sufficient strength, manufacturers tend to err on the side of too much rather than too little. The crash characteristics of composite airframes are quite different from metal or wood – composites do not bend much at all. Their ultimate breaking strength is often higher than metal or wood, but when they do break, they tend to shatter into small, often sharp pieces. Another problem with composites is water getting into the (sometimes foam-filled) structure through minor dings and cracks – good reason to make sure any puncture in the skin is fixed immediately.

Seatbelt airbagRecent developments in light aircraft safety have seen the appearance of ‘inflatable restraint systems’ – or seatbelt air bags. As far as I am aware, these are not yet offered as standard on any LSAs but no doubt the time is coming. At US$1,000-1,500 per seat, they are probably worth considering. A ballistic rescue system for an LSA costs in the region of A$6,000, so seat belt inflation systems could represent (expense-wise) a half-way house.

 

In summary, when choosing an LSA, only you can decide which safety features are important for you. I know some pilots who won’t fly an aircraft unless it has a ballistic rescue system. Others work on an ‘it will never happen to me’ basis. In between these extremes, weigh up the primary and secondary safety elements and give them a weighting that’s important to you. That way, at least you’ll choose an aircraft that you know is right for you.

One thought on “Choosing a Light Sport Aircraft (LSA) – 4 – secondary safety

  1. Hi Peter Cubcrafters have a seatbelt airbag harness option available in the USA FYI

    Regards Stephen Buckle

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