Originally Posted by
Old Aero Guy
Therefore, airplanes shown on the same TCDS can vary widely in their design philosophy and features.
To share the same TCDS, they must have the same fundamental airframe and systems, they share the same fundamental design philosophy, otherwise certification authorities would demand full recertification.
To suggest that this is not the case on the 737 and 747 is false. The fundamental systems and airframe philosophy has changed little for those types, the fundamentals remain the same, e.g. the overhead panel on the 737 has not changed since the 1960s, people are still turning off the hydraulics in flight when they mean the anti-ice 40 years later. The 737-300 retains 80% airframe spares commonality with the 737-200.
Originally Posted by
Old Aero Guy
For these reasons, the linked report does not lump the 737-100/200 with the 737-300/400/500 or the 747-100/200/300/SP with the 747-400. Likewise, the A300-B2/B4 is not included with the A300-600.
The report does not say that at all, it just splits them up when they were introduced in service, it does not give a rational for doing so.
Even with this statement the grouping was skewed to suit Boeing, as the 747-300 entered service after the 757 and 767, and at about the same time as the A310. The 737-300, 757, 767, A300-600, A310 all entered service within a year or two of the 747-300.