Inspections for properties funded with the Housing Trust Fund Program use their own sampling NHTF 24 CFR 93.404(d)(2)(V)
The regulations state:
Inspections must be based on a statistically valid sample of units appropriate for the size of the HTF-assisted project, as set forth by HUD through notice. The grantee must select the sample. For projects with one to four HTF-assisted units, the inspectable items (site, building exterior, building systems, and common areas) for each building with HTF-assisted units and 100 percent of the HTF-assisted dwelling units must be inspected.