Bjorn’ s Corner: New aircraft technologies. Part 44. Operation and Continued Airworthiness

By Bjorn Fehrm

January 5, 2024, ©. Leeham News: We are discussing the different phases of a new airliner program. After covering the Design and Production, we now look at the Operational phase of a new airliner family.

For the customer, the design and production are exciting and interesting, but it’s the information and services around the operational phase (Fleet Support in Figure 1) of the airliner that are most important to the airline customer.

Figure 1. The development plan for a new airliner. Source: Leeham Co.

Continued Airworthiness

We have described the large work involved to get the design and production of the aircraft certified. But the certification for the aircraft doesn’t stop there. During its whole operational life (which is around 25 years compared to the two years in production), there is regulatory oversight and certification of all aspects of the operation of the aircraft.

Each country regulator makes its own Continued Airworthiness rules, but they are normally based on the large regulator’s rules with additions for any special conditions that might apply. We will use the US rules as an example for Continued Airworthiness regulations.

To explain how this all fits together in the US, we use a chart originally made by a consultant and an FAA official named Wyman Shell (thus the chart name), Figure 2. It explains how the FAA regulations are related.

The left-hand side shows the 14 CFR Parts that handle the Original Airworthiness, that is, the Type and Production Certificates, and the right-hand side shows the Recurrent Airworthiness, which is how to ensure the aircraft stays safe when in operation. It shows that development and production are only half the regulations.

Figure 2. The Wymann Shell FAR Chart explains how 14 CFR Parts relate to each other. Source: FAA. Click for easier read.

FAA statistics show that the right-hand side, Recurrent Airworthiness, is more a cause for aircraft accidents than the left-hand side, Type and Production Certificates. The attention around the rules and their procedures is, therefore, on the right-hand side, the measures on how to improve operational safety.

We will discuss the blocks to ensure Operational Safety that are closely related to the aircraft (the operational rules for an airline are for another article series).

Crew and Mechanics Training (14 CFR Parts 61, 63, 65)

As we produce an airliner under Part 25 with >12,500 lbs Gross Weight and as we intend for its use in scheduled airliner service (Parts 121) or charter (Part 135), we need to establish an aircraft type rating, and pilots must be trained & licensed to fly our aircraft prior to in-service flying. We also must train the mechanics that shall service the aircraft on the flight line and in the hangars.

To accomplish it, we need aircraft operations and maintenance manuals and a training syllabus for the Crew and Mechanics. We also need the training tools (Simulators, iPad courses, Suitable training facilities and systems, access to aircraft, etc.). Smaller OEMs establish cooperations with large Training and Simulation companies like CAE and L3Harris, while large OEMs like Airbus and Boeing set up their own training.

After the initial training, there are skill check sessions in a simulator for the pilots every six months and a deeper check every two years.

We also have regulations around Safety Monitoring and Reporting (14 CFR Part 21.3, 39) and Instructions for Continued Airworthiness, ICA (14 CFR 25, 33, 43).  The bulk of the ICAs are instructions for maintenance. These are large subjects that we will handle in subsequent Corners.


12 Comments on “Bjorn’ s Corner: New aircraft technologies. Part 44. Operation and Continued Airworthiness

  1. Interesting rather than boring times for Boeing after an explosive decompression on a new Max-9 after asking the FAA to exempt its 737 MAX 7 from certain safety regulations.

    • Alaska has grounded all of it’s Max 9’s. Will the FAA follow suit and ground it for everyone until this issue is resolved?

      • As the MAX has been flying for some time now, I doubt it.

        This looks to be a one off installation negligence.

        Putting exits on and off is something newer and I believe there was an issue in doing so.

        No disagreement this is another black eye.

    • Mark:

      I don’t see Boeing have asked for a waiver on this aspect, its a more nuanced than that by a lot.

      As I understand it, its a system that has a lot of hours on previous models and the waiver is to continue that method while they look at the paperwork details.

      I have seen vastly worse situation deferred when action should have been taken immediately.

      • TW,

        I was also not thinking there is a correlation between this quality issue and the exemption, but it doesn’t “look good” to be asking for a safety regulation exemption under the circumstances. I did consider that the exemption issue was not related when I posted and mentioned it, but it is such an obvious bad timing situation it could not really be ignored.

        There have been long discussions on the grandfathering of old type ratings and the wisdom of this, but it has been said the accident is not considered to be a design issue.

        Nonetheless, its hard not to imagine the possible worst case scenarios – I just heard on the NTSB feed that the decompression below open the cockpit door and sucked the laminated checklist out of the cockpit…

  2. This clearly a different failure. The entire door is gone, no strucutral damage.

    That points to the door itself exploding outwards which is truly amazing.

    Its going to be interesting to see what they fill that hole with, be it a full fledged door that is covered up or a different unit.

    There should have been structural damage around the door as it let go, its going to be interested.

    Great news is no one was sucked out or injured and it was early in the flight climb so the differential hasn’t as large as it could have been.

    No way to start the year, as was noted above, so much for Boeing Boeing.

    • This is an outstanding site and does a great job going over the removable door setup.

      I am beginning to think that some or all of the securing bolts were not installed. Very possibly none due to the lack of tearing damage.

      It looks like the door opened up and removed itself with spring assist.

      Stunning and amazing and a phew as to all surviving. Many flights are packed full, as always, excellent add to never take your seat belt off unless you need to move out of your seat.

      • Smells like some bolts were missing. We’ll see the NTSB conclusions. With Toyota logic you have 7 other locations were there are fasteners missing that need checking.

        • Low quality work and no functional supervision/checking.

          That is the wrapper issue now.
          apparently expanding at lightspeed now.

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