0
$\begingroup$

Very basic question:

Why do we need Design approval phase in aerospace? Shouldn't it be the product approval that matters? -> How does design ( 'How we achieve the requirements') matter?

I was working in consumer electronics and I have never heard of this 'design approval'.

$\endgroup$
8
  • 2
    $\begingroup$ The short answer is because consumer electronics rarely kill people if there are flaws in the design. $\endgroup$ Commented Dec 12, 2023 at 14:07
  • $\begingroup$ So does automobile/aero follow the below approach? 1) Check performance specification 2) Derive design meeting the specification 3) Wait for the approval 4) Once approved start production based on the approved design. What is production approval, then? $\endgroup$ Commented Dec 12, 2023 at 14:09
  • $\begingroup$ I don't know what the automotive industry does. There are Federal safety regulations manufacturers are required to follow, but i would imagine there are some differences between industries. $\endgroup$ Commented Dec 12, 2023 at 14:14
  • $\begingroup$ Some electronics are dangerous and have lead to approval process'. Generally killing customers is frowned upon so in industries where its happened the government has stepped in. $\endgroup$
    – Dave
    Commented Dec 12, 2023 at 17:47
  • 3
    $\begingroup$ Consumer electronics have approval processes. Radio transmitters require approval from FCC and other national bodies. In North America, UL/ETL/CSA approval (listing) is required by retailers to sell things that plug into the wall. Japan similarly requires PSE approval. The big exception is Europe which only requires self-certification (CE mark). $\endgroup$
    – user71659
    Commented Dec 13, 2023 at 0:15

4 Answers 4

5
$\begingroup$

The short answer is because consumer electronics don't kill hundreds of people at a time if there are flaws in the design.

Safety is the main reason why we have the FAA, and design reviews can save costly errors later in prototyping.

$\endgroup$
4
  • $\begingroup$ “Consumer electronics rarely kill people if there are flaws in the design.” - shock and electrocution hazards are very common in consumer electronics and do have to be mitigated, particularly with any device connected to mains power or can store large amounts of electrical energy. $\endgroup$ Commented Dec 12, 2023 at 18:50
  • 1
    $\begingroup$ @Romeo_4808N, I'm not saying hazards to consumers shouldn't be mitigated, but risk is the product of probability and severity, and a zesty spark from your cell phone is a far cry from killing a few hundred people in a major crash. They really aren't even comparable. $\endgroup$ Commented Dec 13, 2023 at 14:16
  • $\begingroup$ Consumer electronics have some hazardous parts sure, but those hazards can usually be contained to small parts of the overall system, and the response to a fault detection can be to just shut the system off. $\endgroup$ Commented Dec 15, 2023 at 20:27
  • 1
    $\begingroup$ @MichaelHall unless zesty sparks from your powerbank are the causes of multiple plan crashes ... $\endgroup$
    – EarlGrey
    Commented Dec 18, 2023 at 10:16
3
$\begingroup$

It's mainly because in aircraft design, risk mitigation is built into the basic design, and incorporates various risk mitigation principles such as redundancy, fail passive design, human factors etc, determined by regulatory and industry agreed-upon standards.

For example, there is a detailed system analysis that looks at failure modes, the follow-on effect of failures, the mathematical probability of negative results flowing from failures, that sort of thing.

A risk hierarchy is used, that designates events a Minor, Major, Hazardous, and Catastrophic. Catastrophic is total loss of an airframe due to a single initiating event. The risk requirement for a catastrophic event, following something breaking, is a probability lower than one in a billion. For the lesser categories, the probability level is less onerous.

So the OEM has to submit a design along with a comprehensive analysis, and show in its design that the risk mitigation elements are built into the design to meet the regulator's standards, by justifying that its design choices satisfy the regulatory/industry standards.

The authority might reject the analysis that substantiates as particular design, and demand that redundancy be added by including a backup component or second channel to a system, depending on the risk category it falls under. This all happens during the Design Reviews.

You want all of this worked out beforehand before you start to cut metal, to minimize the chances of unpleasant surprises, so that's the main reason this process is used. The only other industry that follows this sort of design protocol is the nuclear industry, which has more or less adopted aviation risk mitigation standards (carried a little too far some say, which is why it's so difficult to build a new plant in the US).

The 737 Max fiasco was fundamentally a breakdown of the process at the design review/approval stage, where the FAA accepted a failure effects analysis for the MCAS system that was inadequate at risk mitigation (using a single AOA vane channel as an input source). Boeing declared an MCAS failure as equivalent to a Stab Trim runaway, and based the system architecture on the that failure mode (which was only at the Major risk level IIRC). The FAA had gotten too comfortable at accepting Boeing's analysis at face value, even accepting the initial pitch issues found during flight testing.

In addition, when Boeing discovered the issues with MCAS affected a wider envelope than they'd originally told Boeing during flight testing, they hid that from the FAA (why the Chief Test Pilot was charged).

So you could say that the MCAS story demonstrates why this entire protocol is used in the first place, being a demonstration of what happens when it breaks down.

$\endgroup$
1
$\begingroup$

There are sectors that require design approval, like offshore and ship cranes.

Additionally, the design of appliances is currently regulated, see the webpage of the chinese branch of the German testing company Dekra:

Have their designs met safety standards, such as electrical insulation, materials, structures, electric leakage, short circuit, overload, overheating?

$\endgroup$
-3
$\begingroup$

enter image description here

enter image description here

In production approval, the company must show they’ll test and verify the product to ensure it meets FAA standards for its particular design and function. The agency will need to ensure that a system for production is in place to verify that each manufactured part matches the FAA-approved design. enter image description here

enter image description here [Ref1] [Ref2] [Ref 3] [Ref 4]

$\endgroup$
2
  • 4
    $\begingroup$ This answers "what" the FAA does, but you specifically asked "why". $\endgroup$ Commented Dec 12, 2023 at 14:43
  • 4
    $\begingroup$ Please convert the image to text so that it can be searched, and so that it can be read by screen readers for vision-impaired users. Posting an image of text isn't a preferred technique on Stack Exchange boards. $\endgroup$
    – Ralph J
    Commented Dec 15, 2023 at 4:06

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .