In plain English
FAR 52.247-5, Familiarization with Conditions, is a contract clause prescribed at FAR 47.207-1(d), 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 47.207-1(d), insert the following clause in solicitations and contracts for transportation or for transportation-related services to ensure that offerors become familiar with conditions under which and where the services will be performed:
Prescribing reference: FAR 47.207-1(d).
The official text, verbatim
As prescribed in 47.207-1(d), insert the following clause in solicitations and contracts for transportation or for transportation-related services to ensure that offerors become familiar with conditions under which and where the services will be performed:
Familiarization with Conditions (Apr 1984)
The offeror shall become familiar with all available information regarding difficulties that may be encountered and the conditions, including safety precautions, under which the work must be accomplished under the contract. The offeror shall not be relieved from assuming all responsibility for properly estimating the difficulties and the cost of performing the services required in this contract because the offeror failed to investigate the conditions or to become acquainted with all information concerning the services to be performed.
(End of clause)