Bjorn’s Corner: The challenges of airliner development. Part 13. Later in the Prelaunch Phase

By Bjorn Fehrm, Henry Tam, and Andrew Telesca.

July 23, 2021, ©. Leeham News: Last week, we went through the initial tasks in the Prelaunch Phase. We talked about Sales and Marketing activities, initial Concept development, and first Supplier contacts.

Now that time has passed, we are three quarters into our Program Plan (Figure 2), and we have to refine our Concept, select Suppliers, and dig deep into how to get Certification.

Figure 1. Windtunnel test of a half model of the wing and high lift devices. Source: ONERA.

The Pre-Launch Phase’s later stages

We are now three quarters into our two-year Pre-Launch Phase, Figure 2.

Figure 2. The Program Plan for our Green 19 seater. Source: Leeham Co. Click to see in full scale.

It’s time for us to get going on the following fronts:

Refine our Concept

By now we shall have picked a final CAD/CAM package where we can create and store the final external shapes after the analysis in our CFD tools. As we see the form of the aircraft and its movable surfaces mature, it’s time to do a detailed windtunnel model. Once again this is focused on the low-speed regime, takeoff and landing.

Now we must have the final wing shape and high lift configuration so we can predict the maximum lift in takeoff and landing configurations, and also measure the moments these configurations generate on the aircraft.

The moments give us input, together with the engine thrust for single-engine takeoffs, for the final sizing of our empennage surfaces (vertical and horizontal tails). The windtunnel model we either make or let make is larger and more detailed than the first one. Size is important to get good data so we might go for a half model at a scale of 20% of the real size, Figure 1.

The data shall be part of our design database, giving the stress loads on all parts of the aircraft from normal aero loads but also extreme cases like gusts. We also need other loads like hard landings and engine-out flight cases. Once we have this dataset we can test different structural concepts for weight, flutter and fatigue resistance, and production cost. Our aero and stress engineers are maxed out during this period.

With the data from CFD and the windtunnel and initial system configurations, we can make the first Functional Hazard Analysis (FHA). Now we test what the hazards to aircraft are if systems fail, such as the flap system deploying asymmetrically caused by e.g. a sensor failure, or not at all due to hydraulic failure. We need these first FHAs for internal work but also for discussions with the Certification Authorities, see below.

Supplier selection

Our engineering and purchase teams are now hard at work to select suppliers for Structures, Engines, Landing Gear, Avionics, Flight Control Systems, Fuel System, Environmental Control Systems (ECS), Hydraulic and Electrical Systems, Bleed-Air system, De-Ice System, Cabin and Cargo equipment etc. We also need a supplier for our Electrical Wiring Interconnect Systems, EWIS.

We need to establish the type of contracts we shall have with the suppliers such as time schedule and price for initial deliveries based on our present versions of specifications for all the parts.

Any milestone payments for shipments must be agreed upon, and how is the inevitable learning curve handled. Does the supplier absorb the extra cost for initial shipments or do we? And how do we get the benefits of the cost down as deliveries reach higher shipset numbers (the extra cost of initial shipsets can last until past 200 units, dependent on if we have a new design or use one already in production at the supplier)?

Our contract shall regulate how we handle specification changes. These are inevitable as the aircraft and our project mature. It’s better to agree on how such changes affect delivery and costs upfront.

Certification work in the Pre-Launch Phase 

We discussed how certification standards shape our aircraft in previous articles. As we advance through the Pre-Launch Phase we need to understand how we can get certification compliance in several target markets:

  1. What should be the “State of Design” for the Type Certificate (i.e. the certifying country)? And shall we produce the aircraft in the same country (for this we need a Production Certificate)?
  2. What countries are the priority for validation of our original Certificate (each country has to issue an airworthiness certificate for the aircraft)? It can be based on the State of Design certificate but this has to be validated by each country where we shall sell and operate the aircraft. When do we need those efforts to start?
  3. How do we manage architectural-level configuration options; like passenger version, cargo version — in what order do we certify these?
  4. Are there any critical regulatory decisions that will influence our designs– for example, special conditions for new technologies we use?
  5. Are there upcoming regulatory amendments in our target countries that could influence our design, either the initial or a future configuration, such as harder environmental regulations?
States of Design and Production

The choice of State of Design that will grant the type certification is important. It determines the certifying authority (e.g., FAA, EASA, etc.) for the project. All other certification decisions are influenced by this decision. Examples of what we need to think about:

  1. Does the authority have experience certifying our design type and manufacturing technologies?
  2. Will the type and airworthiness certificates we receive be recognized (with limited efforts) in the countries we want to sell in (for example if we choose India as the State of Design, will their certification be recognized in other countries?)
  3. Are the airworthiness requirements for our product well defined by the state? Are they more conservative than in other potential states of design?
  4. Does the authority have resources available to support our program on the required schedule?
  5. Is their current administration more focused on fostering innovation and supporting new products, or concerned about their own reputation for public safety? Does our company have the potential to influence this (probably not, as we are an upstart)?
Validation Planning

In addition to the question of where we get the initial type certificate, we need to understand where we will need to validate that certificate in order to sell aircraft. This is based on our sales forecast: Asia, Africa, and South America and potentially Europe/Canada for the passenger variant, and the US for the cargo variant.

Certification and Sales departments need to work together to establish the timelines in each region, so we can deliver when we need to.

For example, it would be very difficult to deliver in the first quarter of our delivery program to China (under the CAAC), Brazil (under the ANAC), and the USA (under the FAA), as each of these agencies require substantial certification/validation efforts.

We could try to engage them simultaneously, but this risks instability around the initial design as these agencies give us their requirements and it would be difficult for us to fulfill these requirements in one go. It could delay our program if we try to shoot for too many validations simultaneously.

On the other hand, waiting too late to make an engagement could result in a surprise design requirement that delays validation and delivery to that specific country.

The most underestimated part of aircraft development

All this work with the certifications is underestimated by all upstart projects. We have yet to hear of any upstart aircraft program that says “by the way, the certification efforts were as planned, and we got the certification when we planned it“.

We go back to this critical and chronically underestimated part of aircraft projects as we dig deeper into our program.

23 Comments on “Bjorn’s Corner: The challenges of airliner development. Part 13. Later in the Prelaunch Phase

  1. There is a risk for requirements creep and weight, time and cost to start sliding away. It takes experienced cheif design engineer and project mgr. to keep everybody focused to meet requirements but no extras unless given for free.

    • Indeed, Claes. We will address this in-dept as we come to detail design.

  2. Interesting to follow and clearly you would want FAA/EASA and possibly Brazil as the certifying county. All with experience of new aircraft and these days still a lot of cross recognition .

    • Yep, there are recent projects that can testify to this.

      • Bjorn:

        Off direct topic aspect , do you have the reasoning as to why the A400 and KC-46 were specified to meet EASA and FAA certifications?

        • Allied military have been tending to require civilian certification for military-oriented aircraft for some decades now.

          Lockheed-Georgia did that for the base C-13oJ. I don’t know about passenger carriage, they certified some earlier versions, IIRC the H, for civilian cargo. (Model L382x, marketed as L100. Pacific Western, Saturn, and some shortlived Alaskan carriers serving oil exploration were among operators, perhaps Delta for a little while.) They are now pitching sales for commercial use.

          Reasons include getting the benefit of safety knowledge that civilian regulatory agencies have.

          I read that the KC-46 is built to civilian standards, including basic provisions for military equipment. Then military equipment is added. I speculate that allows Boeing to use FAA production approval. (It is built next door to civilian B767s in Everett, I don’t know if it is flown to Wichita to add the military equipment.)

          • KC-767 was highly civilian based, the KC-46 much less so. The hardening changes required by USAF are a large part of the development cost overruns on the KC-46.

            Civilian certification was part of the transport requirement, which recognizes advances in civilian sector safety standards. Rathe than duplicate those in the military certification, it’s more cost effective to require civilian certification.

          • Rob:

            I have not seen anything that the hardening was an issue.

            The wire bundle separation certainly was major.

            The wing drogues were cited as the main certification hold up.

            There is an odd use of the fuselage as an antennae as I recall that also had problems.

            That is aside from the nit noid problems like FOD , cargo clamps failing and the contamination of the fuel system.

            The boom vision system is the main remaining issue on Boeing.

            The USAF is paying for the shock absorbing issue as it was their spec.

        • It’s an interesting question. Just googling this issue comes up with the following:
          1 Joint EASA/FAA civil certification ensured the highest standards of safety. It proved to be both a challenge for EASA, Airbus and Tourbomeca. Additional Military certification requirements were added on top eg for in flight refuelling etc.
          2 It was a solid basis for certifying for other nations militaries.

          3 Most important was I think that it certified the entire supply chain.
          Any technology developed would then be incorporated in future airbus products. A lot of A400M technology helped with the A350.

          Perhaps Airbus was also hoping for civilian customers in the heavy lift outsize load area.

          • Item 1 makes some sense (as does previous).

            As far as I know the P-8 is not certified that way (though basic build is to Boeing standard NG which no reports of fit failures on like the 787).

            The P-8 has sold well to other military around the world.

            Maybe the split comes between transport and combat (which the P-8 would be and no one has certified to civilian standard weapons)

            I don’t see KC-46/C-130 or the A400 sharing tech with Civilian programs (benefit from them in KC-46 maybe)

            Lockheed has made Civilian C-130 models so there would be a link there and they have a Civilian J Model (working on?)

            I don’t know anyone civilian wise is envisioned buying and A400. A400 Crash was due to a failed process in software load which should not happen. T

            Just an odd certification area.

        • If my memory is correct, part of the rational for A400M was to allow civilian operations if needed.
          In addition, there is a consequent added value when you want to “re-use” equipments / systems for another civilian A/C: you can then claim the highest TRL level and take credit of the existing qualification/certification (provided required levels are the saim) by similarity, without test.

          • I think all military aircraft have Civilian airspace use built in now, or added.

            At least in the US Federal agencies were exempt from Certification requirements. I think that is still technical true but after a weird glider conversion to propellers (WII era) that crashed in AK, it was mandated they needed an exemption to do so (not for routine flights like the Glider hauling freight – some kind of pure need which unlikely.)

            A400 did start out as a offering from the Civilian side of Airbus (technically still is but reality was it was a military project and they shifted)

            What I don’t see is shared equipment with civilian side. Those aircraft are one off that aren’t going to carry a 777 type Air Conditioning system.

            Actuators etc would be unique to an air-frame. General design might be the same but sizing etc different.

          • More importantly Airbus and it’s supply chain learned to make a large scale civilian CFRP aircraft.

          • There is that. Did they use the same frame and panel method per the A350?

            I think that is what the V-22 did

          • @ TransWorld

            “What I don’t see is shared equipment with civilian side.”

            At sub-system / equipment level, a lot can be shared: hydraulic / electrical actuators, hydraulic components (check valves, accumulators, blocks…), sensors…
            It may not concern directly an airframer but since it could be a cost killer for a supplier offer, the benefits is real by reducing development / qualify risks, costs and delays

          • Perhaps a bit of irony that Airbus used the military A400 as the tech basis for the A350.

            Isn’t that what the terrible Boeing is often accused of?

    • TW. Canada was very experienced as well, especially after the
      Bombardier C-Series program.

      With that gone to Airbus, there is Bombardier business jets (regional jet program now under Mitsubishi dormant), PWC engines is quite active, Bell Helicopters civilian models, and whatever Longview/Viking does in near future (recently finished EAF version of CL415, produces Twin Otter -400, production paused on Dash8). Can’t think of anything else.

      • Agreed on Canada. Thought about adding it to the list.

        Close proximity to US/FAA as well as those other activates on engines (do they make any Helicopters in Canada?) . The legacy program would seem less relevant but they would still have to meet the original build spcs.

        Cost wise though US is probably a lot lower cost (Airbus has stated that mfg in the US in total is lowest)

        Japan wouild seem to be as well but clearly while they have the agency they are not up to speed on a Certficaion proces (Space Jet moved to US)

  3. I think that whichever state of design and production you choose, you still also have to comply with the local jurisdiction where you locate your production and intend to carry out flight tests.
    It should not be a major concern but otherwise, your first flight may not be granted.

    • 757 and 777 up to the X as well.

      I think what we have seen is a crossing of trying to maximize production while the leadership was being cut and its wound up in tragedy in the MAX case and huge impact on the 787 and 777X.

      Suck the yoke out of the egg and there is none left after a while.

      Even if Boeing is serious about cleaning up certification, it will take years to re-build the system. In the meantime the past failures keep showing up.

      It shows how badly the ODA system has failed. At the very least they should revert to FAA direct reporting (the FAA has to maintain its end as well and that was dropped from what I can see).

      Av Week reports a significant disagreement between FAA oversight and the Boeing Oversight of the ODA and the failures to process the issues the way they should be.

      One part reports that they just cut and pasted 787 control program into the 777X (they are using the GE system that is on the 787).

      The controls issue would seem to be a Space Capsule type problem where they assumed and did not confirm.

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