Hello Graham,
I’d like to point out that the type of assessment that is done by manufacturers is quite different to that of independent T&E assessors.
Manufacturers will be demonstrating that their product meets the contracted requirements, no more.
Independent T&E looks firstly at safety and secondly at fitness-for-purpose.
Now, you may well suggest that these should have been covered by the requirements in the first place, but in the real world it just isn’t this simple. So let’s look at two options – build to order and off-the-shelf.
If a platform or system has been designed to order, then there is much more scope to have the contracted requirements tailored to the intended role. However the process of design and production will be an extended one – Eurofighter Typhoon took 20 years. In that time there will inevitably be many changes in operating environment, role, safety regulations, threats faced, technology etc. For instance, since Eurofighter was first designed we have seen the end of the cold war, and the introduction of global GPS coverage. Both have a huge impact on how a combat aircraft is used. So we can then start altering the requirements as we go through the process of development, this inevitably leads to delays and increased cost. Plus, once this starts happening, there is an effect on the requirements that you already have in place.
Take the example of the car – you decide that you want to have a car designed to your own specifications. So you set out the design for a high-powered sports car. But during the process of development a new fuel is launched that is much more efficient. You decide you’d like to utilise this – it requires a re-design of the engine and fuel system. But it may also mean that the car can no longer meet your original performance requirements. You decide that provided the performance is reasonable you will still accept the car. When the car is finished, you hire someone to test drive the car and measure its performance, to ensure that it still meets your needs.
If a platform or system is purchased off-the-shelf, then it’s always going to be a compromise, because it isn’t designed to be exactly what you need. Your aircraft may be sufficiently flight-tested and airworthy, but it can’t land on your aircraft carrier without modification. Or the comms system isn’t compatible with the rest of your network. Or you want to put proprietary security systems in, instead of relying on those provided by a foreign country. It may come with clearance for weapons or sensors, but not for the weapons and sensors that you have in your stores. Or it may have been designed to carry out an air-to-ground role in the desert and you want it for maritime ops in the Antarctic.
To labour the analogy with the car – you decide to buy your car off the shelf. You look at the cars available and decide on an Italian model. Unfortunately, it only comes as a left-hand drive which your insurance company won’t cover, and there is no option for ABS (the Italians don’t do braking!). Additionally, it needs special tyres that can only be provided by the manufacturer, and these cost ten times as much as the local equivalent and have to be ordered six months in advance. So do you modify the car, and thus have to have it assessed? Or just live with the shortcomings?
Modern day T&E is highly geared towards testing as little as possible, but as much as is necessary. It’s about deciding what we need to know about a system, in order to determine that it is safe and effective as it is intended to be used. Then seeing what evidence already exists (and is available to us), what can be reasonably deduced and what must be generated by testing. Rig testing and software modelling are extensively used so that flight testing is reduced as much as possible.