Design Phase Product Integration Management- A new GA Aircraft 6

[Casilero]

I need to answer a question about a practical thing in aircraft design management...maybe you could help?

Here goes......during the design phase, for PDR, all the systems have to be integrated into the wing, engines, fuel lines, landing gear, wiring, flight controls, the whole lot that bolts onto the wing. The question is what interface project systems are used in reality to make sure for example all the integration checks are carried out. By system I mean an ISO or EASA AMC or perhaps SAE ARP4754 protocol to list out what should be done to check the matching of parts for all the reasons from galvanic action to vibration to interface gaskets, safety analysis, etc. I refer to the US or EU environment here to try to establish what compliance requirements might be cited in a compliance review for a Design organisation in the civil aircraft sector.

What to you do in reality to manage this? I used to use Do178 for avionics, mainly specifies the connector socket.

Any tips come to mind?

Much appreciated.

 

[Casilero]

Very interesting, am investigating this reference.

There is a huge issue about a small Pt 23 aircraft being funded by investors Vs a goliath company developing a new or derivative airliner.
In all cases there has to be carefully controlled financial decision making but this is hampered by the real world problem of the cost of development prediction which even the best cannot forecast with accuracy. The end cost can easily be 3 times the predicted cost. These projects are often fraught with distress as the project inevitably goes off track financially. This is is an issue that is not written into project management methods.

 

[rb1957]

ok, wow ! I'm just so confused as to where you are, where you're going, etc ...

we started with system interfaces, an aileron PCU got an honorable mention, went through a FAR23 wing, and now it's a critique of stress reports.

ok, there are good reports (that allow you to understand what the guy was thinking all those years ago, and why, and then why he thinks it is ok),
bad reports (much like you're mentioned ... reams of data (easier today with pictures) but little "understanding"), and then there are awful reports (that just confuse you).

Quality of a stress report is one thing. I think the stress report exists (mainly for OEMs) so that later generations can understand the design and it's analysis so that they can extend this analysis for MRBs (or NCR or RNC or ... manufacturing defects) or for future redesign. Of course the other reason for a stress report is to assemble the data supporting compliance (which at OEMs is usually "by test").

 

[Casilero]

"Consider a 30-year career...
Do you want a career where you repeat 1-year 30X... that's' OK... and possible.
OR do you want a 30-year career where each year's experience is

The above message came in by email but has not appeared yet on the forum. As the author says, we only get a thing slice of project generally and the era of WW2 designer individual has gone. That's why I was intrigued by aircraft design, that kind of oversight of the whole process from the market environment to the factory floor and everything in between. Being brought up in a family business in a technical field which has to find the customer, convince the, build their bespoke stuff, and get paid, it was sort of natural to think this way. But the industry is now massive and very few people have the privilege of a birds eye view of a project.
But let me make a slightly different point and that is what is more appropriate is to view project management in the context of teams as opposed to department or individuals. I mean a vision of project management through team behaviour and strong formation and as Kelly Johnson set out, build strong teams and let them at it and get them to sort out non routine issues firstly (the unknown risks) and the routine challenges will kind of sort them selves out by natural forces of the strong team.

There was some pleasure in keeping it simple and the scale of IT knowledge now needed is often overwhelming and confusing. Our senior mechanical engineering teacher at college had been a 'lofter' on Titanic-setting out the curves, an expert on integration of curves. He showed some hull drawing from that era and explained that the pencil lines on drawings , the line weight, and dash spacing would specify the plate weight or beam features and would need no further explanation on the ship yard floor as the fabricators knew the drawing convention and this avoided elaborate system of BOM and so on. The hull drawing were surprisingly simple. A bit like an old tailors shop.

 

[IRstuff]

How did it all become so complex. Does it have any value all this extroardinary reporting.

Note that the complexity of many new planes are driven by fuel economy, reducing weight, and designing airfoils and wings that can't even be flown under manual control to make air flight less of an impact on fuel consumption and air quality. If these are not important to you and your descendants, then there is no value, if they are important, then this complexity is a necessity.

 

[Casilero]

RB1957 and all the learned people who contributed

I think it is time to close this conversation as it has drifted across many areas, Project Management, governance, system of regulations, digital issues, composites and it all very interesting but academic in a context where the challenges in the project are unknown. Like many anomalies in aviation , it started a small enquiry and snowballed. But it has been worth while and I wish to thank any who was kind enough to contribute.

Over and Out for Now.

Ps the gent I referred to above started in 1911 as a lofter apprentice as a boy, still teaching in ethe arly1980's but getting on a bit!.

 

[kontiki99]

You might start looking over the data from The General Aviation Manufacturers Association (GAMA).

Home - GAMA

Event

gama.aero

 

[SWComposites]

How did it all become so complex.

Sigh. Its because it is far far too each to create a ginormous FE model with a few button pushes. All real thinking and understanding of structures seems to be disappeared. Its all about, "are there any red elements in the FEM output". we are doomed.

 

[SWComposites]

for example a HC panel today and the way it is manufactured, is it any better than it was 40 years ago? (better = durability, weight, cost)

short answer, no. there have been some improvements in prepreg material quality, leading to fewer defects (assuming everything else is the same). but the push for outsourcing to low cost labor sites has adversely affected quality.

 

[Casilero]

SW I have to agree with you on several counts. NDT is a bit more advanced. (probably to catch increasing defects) Then Vacuum Resin Infusion, hot drape, also. Last project I did paid me to look deep into composites theory in the 60's because that's where a lot of the theory started. The research done then was vast and a lot of it is untapped yet., but economically there might not be a market. The bigger brief was 'take this old composite aircraft' and update it for the present 2024. The result was, it could not be made better that it was then.

 

[GregLocock]

" it could not be made better that it was then"

BTDT

Ford Thunderbird 1955 restomod.

Project: use FEA to come up with a better torsional stiffness for the same mass for the ladder chassis, sticking to steel, and same packaging.

Answer: nah, the geezers who designed that chassis had been designing fighters 10 years earlier, they had a very good design. There were a couple of features I could have added (basically shear panels) other than that we had to break the packaging or increase the mass.