The Quiet Retrofit

The quiet retrofit is From the Surviving Record's term for a design or regulatory change made after a failure that can be traced in the record: a revised standard, a new inspection rule, a changed drawing.

The word quiet describes how little notice such changes usually draw next to the failure itself. A collapse makes headlines; a revised clause in a standard seldom does. Quiet here means low-profile. It does not mean hidden, and the term never implies that anything was concealed.

The question every failure entry asks

Entries in Engineering Failures ask what was changed afterward. The answer is checked on three points:

• What changed. The change itself, cited to the standard, rule or drawing revision that contains it.
• How public it was. Whether the change was announced, and when.
• The recorded reason. What the documents themselves give as the reason for the change.

When a readable source for any of the three cannot be found, the entry says so instead of filling the gap, and the open question goes into the entry's list of what is still missing.

What a retrofit does not prove

An improvement made after a failure does not show that anyone knew of the fault beforehand, and it is not an admission. Responsibility is a separate question that needs its own evidence; it is never inferred from the fact that something was changed.

Timing is handled the same way. When the record shows only that a rule came after a failure, the entry gives the sequence of dates and any recommendation that preceded the rule. It does not write that the failure caused the rule unless a source says so.

The three checks follow the same evidence levels as everything else on the site, set out on the evidence levels page.