Reserve service life

Emergency parachute systems

Last month we looked at the different types of reserves and factors to bear in mind to make sure they give good service. But how long can we reasonably expect to have full confidence in a piece of equipment on which we may have to rely to save our life in an emergency?

Inspecting and repacking as many reserves as we do at Aerofix, we regularly see emergency parachutes that are no longer serviceable. Sometimes that’s because of damage, or evidence of general deterioration, but sometimes it may be simply that the parachute is very old.

Calling a pilot with news that their reserve is too old to be certain it remains serviceable, and recommending that it be replaced, is not something any professional service workshop does lightly. Replacement will be expensive, and is unlikely to be a welcome expense. Since Aerofix supplies new Gin and Independence reserves, we are always very concerned to make sure the pilot understands our motivation is to ensure their safety, and not trying to making a sale for the business or anyone else.

Manufacturers specify a service life for their emergency parachutes. For most brands that is 10 years, but we know some that specify longer. In those cases, the manufacturers offer extended periods provided the reserve has been repacked and inspected in accordance with their recommendations. It’s worth looking at this aspect when you buy a reserve, because if you think about the cost as an insurance policy lasting for the service life of the reserve, a longer life will give you a smaller cost per year.

For some pilots, cynicism about the motivation of manufacturers specifying a service life is all too apparent online. “They would say that, wouldn’t they – they just want to sell a new one when my existing one is still perfectly good”. And that response is perfectly understandable. Another response is to ask about the scientific basis for concluding that a reserve is no longer safe to use – surely it must be possible to test whether a reserve is still safe?

The basic problem for manufacturers is that they know the materials they use degrade over time and become weaker, similarly to our gliders. But they have no control over the conditions to which the reserve will be subjected. Will the pilot ever get the reserve wet or sit on it on a damp hillside? Will it be left damp inside a harness for months on end? How long might it be baked inside a car in sunny conditions? Will sand and dirt left be inside the harness without being promptly cleaned out? Will it be exposed to UV or corrosive contaminants like salt or petrol fumes? Repeated use of the parachute and even handling during repacking itself can contribute to material strength loss!  Unfortunately, degradation is not visible by simple visual inspection and can only be established by destructive strength testing of the actual material from which the canopy and lines are manufactured. The more experienced manufacturers build in such losses into their design calculations, and their declaration of a ten year service life is based on many years of experience, allowing for the deterioration of synthetic materials in temperate conditions.

For professional service workshops, the challenge is that there are no tests we can apply to reserves to assess serviceability. For gliders, I can remove a line, check it is strong enough and replace the one I took off – but I can’t do that for lines on a reserve. Glider manufacturers all recognise the Bettsometer test of fabric strength, and if we can pull 0.6kg force against the cloth without damage, the manufacturer supports the conclusion that the glider’s canopy is strong enough – but there is nothing similar for reserves. And glider manufacturers stipulate porosity requirements for their wings if they are to be judged airworthy – but the materials of some reserves are designed to be porous and identifying any changes would require very different porosity machinery for measurement, even if the material specification requirements had been defined.

For buyers of parachutes in bulk, like the military, service life may be extended, but only by submitting representative samples to the manufacturer for destructive testing. If you have a fleet of several hundred parachutes that have all been subjected to the same conditions, it may well make sense to send off half a dozen and pay for testing to reach that conclusion. But for individual recreational pilots that’s not an option.

Pilots come to Aerofix to rely on our professional advice and guidance. We apply our experience to the facts and measurements we take, so we can always support the recommendations we make. Manufacturers tells us the service life of their reserves that they are prepared to stand by, so if we are to advise a pilot to entrust their life to a reserve after its service life has expired, we need to have a rational basis for that advice. Unfortunately, without any generally accepted tests, it simply isn’t adequate to say “well, it looked OK to us”, given the critical importance of the judgement being formed.

So where does that leave the individual pilot repacking their own reserve which is, say, 11 or more years old? How old is too old and when should I get a new one? Well, the BHPA has just issued a notice for licensed repackers to provide to pilots (see insert). It touches on all the issues I’ve covered above and concludes by encouraging pilots to respect the manufacturer’s stated useful working life. It’s a really important point we all need to consider. And while all of us hope it won’t come to this, it’s a decision on which our life may depend one day.

If you want to chat anything through, we’re always happy to offer help and advice over the phone (01433 627195) or by email (info@aerofix.com).

 

BHPA Safety Notice

Please read this

Different emergency parachute and harness manufacturers suggest different periods as the useful working life of their products, beyond which they are not prepared to offer any guarantee of their effectiveness. This is because they have no control over the treatment or the environmental factors that their products encounter.

The useful life of your flying equipment, including your emergency parachute is not infinite, all materials degrade over time, and several factors, humidity, temperature, exposure to UV light, air pollution, packing methods, and of course use can affect this life.

BHPA emergency parachute packers can comment upon the appearance of any product, and reserve the right to refuse to repack any item they consider in poor condition; but even apparently suitable harnesses or emergency parachutes may have suffered degradation in performance and structural integrity and it is every pilots’ personal responsibility to ensure that their equipment is airworthy.

Unlike gliders, there are no standardised tests for checking the strength and porosity of harnesses or emergency parachutes.

It is important to consider your system as a whole, there have been issues with small parachutes being insecure in large pockets, and vice versa, and of pilots modifying elements from different manufacturers to fit each other.

Remember that your manufacturers are knowledgeable about their product and give their warranties for what they consider good reasons.  If you are confident enough to use their product, you should respect their prescribed limitations.

If you are not sure that you can rely on your equipment in an emergency situation the only sensible solution is to replace it.

2018-10-10T08:45:10+00:00Reserves|