In plain English
FAR 52.246-1, Contractor Inspection Requirements, is a contract clause prescribed at FAR 46.301, most recently dated Apr 1984. The complete official text is reproduced below, verbatim, from GSA's published FAR source files.
Its text contains no sentence requiring insertion into subcontracts; see the flowdown section below for what that does and does not mean.
Does it flow down to subcontracts?
No flowdown mandate found in the clause text
We scanned the full clause text and found no sentence directing the contractor to insert this clause into subcontracts. That is a statement about the text, not legal advice: a prime contractor may still flow terms down contractually, an agency supplement (DFARS, VAAR, …) may add requirements, and clauses listed below (if any) may order this clause into subcontracts from the outside.
Where it's prescribed
As prescribed in 46.301 , insert the following clause:
Prescribing reference: FAR 46.301.
The official text, verbatim
As prescribed in 46.301 , insert the following clause:
Contractor Inspection Requirements (Apr 1984)
The Contractor is responsible for performing or having performed all inspections and tests necessary to substantiate that the supplies or services furnished under this contract conform to contract requirements, including any applicable technical requirements for specified manufacturers’ parts. This clause takes precedence over any Government inspection and testing required in the contract’s specifications, except for specialized inspections or tests specified to be performed solely by the Government.
(End of clause)