Originally Posted by
tdracer
Nice post, too bad it's almost entirely wrong.
There is something called the "Changed Product Rule" or CPR (and before you get on about the FAA, CPR has been completely harmonized with EASA).
CPR basically says that when you make a major change to an aircraft (and new engines qualify), anything that is changed has to step up to the latest regulations.
If you bother to check the MAX TCDS, you'd find precious few regulations date back to the original 737 TCDS (mainly having to do with structures).
For all the problems with the MAX, the regulations it was certified to are not one of them.
Based on the JATR report it could be argued there is a problem with the changed product rule. Recommendation R1.
The changed system was not required to be tested with a top down approach. Testing on how it integrates with the rest of the systems. Leaving it open the issues we see.
Recommendation R1
Based on the JATR team’s observations and findings related to the application of the Changed Product Rule to the certification of the flight control system of the B737 MAX, JATR team members recommend that the FAA work with other civil aviation authorities to revise the harmonized approach to the certification of changed products. Changed Product Rules (e.g., 14 CFR §§ 21.19 & 21.101) and associated guidance (e.g., Advisory Circular 21.101-1B and FAA Orders 8110.4C and 8110.48A) should be revised to require a top-down approach whereby every change is evaluated from an integrated whole aircraft system perspective. These revisions should include criteria for determining when core attributes of an existing transport category aircraft design make it incapable of supporting the safety advancements introduced by the latest regulations and should drive a design change or a need for a new type certificate. The aircraft system includes the aircraft itself with all its subsystems, the flight crew, and the maintenance crew.
These Changed Product Rule revisions should take into consideration the following key principles:
• A comprehensive integrated system-level analysis recognizing that in this complex interactive system, every change could interact with other parts of the system.
• The assessment of proposed design changes on existing systems at the aircraft level includes using development assurance principles, system safety principles, and
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