Definition
Part 27 of Title 14 of the Code of Federal Regulations (14 CFR Part 27) sets the airworthiness standards for normal category rotorcraft, generally those with a maximum certificated takeoff weight of 7,000 pounds or less and nine or fewer passenger seats. It governs how these helicopters must be designed, built, and tested to be certified by the FAA.
Plain English
Part 27 is the FAA rulebook for designing and certifying smaller helicopters. If a helicopter weighs 7,000 pounds or less and carries nine passengers or fewer, it must meet Part 27 standards to be approved for use.
Context Anchor
Seen in helicopter IFR certification discussions when the handbook explains whether a helicopter is approved for instrument flight.
Derivation
"Part" here refers to a numbered section of Title 14 of the Code of Federal Regulations, which is how U.S. aviation rules are organized. Part 27 is simply the 27th part of that title, dedicated to small (normal category) rotorcraft.
Why Pilots Care
A helicopter must meet Part 27 standards to receive the necessary certification for legal IFR operations and instrument approach procedures.
Intuition Check
Part 27 does not mean a physical part installed on the helicopter. It means a numbered section of FAA regulations.
Example Sentence 1
Most light civilian helicopters, like the Robinson R44 and Bell 206, are certified under Part 27.
Example Sentence 2
Maintenance records documented that all modifications remained within Part 27 limits, keeping the helicopter eligible for instrument procedures.