Restricted-Category Helicopters and Urban Lift Limitations

A helicopter type certificated in the restricted category under 14 CFR 21.25 may not fly Part 133 external loads over a densely populated area, in a congested airway, or near a busy airport with passenger operations. An approved congested area plan does not lift that bar, and the FAA has denied at least four operator requests for an exemption from it since 1999.

Much of the civil heavy-lift fleet in the United States began life in the Army. Surplus Chinooks, Black Hawks and Hueys reach the civil register through a special certification path, and that path attaches a limit on where they can carry a load. For a contractor planning a rooftop set or a steel pick downtown, the limit decides which aircraft can be considered before weight, reach or price enter the discussion.

The rule is easy to misread, because one regulation appears to remove the restriction and a second one puts it back. This article works through both, the FAA's record on exemptions, and what the limit means for the aircraft that remain eligible for an urban lift.

What the restricted category is

An ordinary civil helicopter holds a type certificate issued against the airworthiness standards in Part 27 (normal category rotorcraft) or Part 29 (transport category), and each airframe carries a standard airworthiness certificate. The restricted category is a separate route. Under 14 CFR 21.25, an applicant is entitled to a restricted type certificate for special purpose operations if the aircraft either meets a category's airworthiness requirements except those the FAA finds inappropriate to the special purpose, or is a type manufactured for and accepted by a US armed force and later modified for that purpose.

Vertical Magazine lists the military types flying in the civil restricted category as the Boeing CH-47D Chinook, the Sikorsky UH-60 Black Hawk, the Sikorsky CH-54 Tarhe, the Hughes OH-6, the Bell OH-58, the Bell UH-1 and the Boeing CH-46D. A standard category helicopter can also end up restricted when it is modified for a special purpose, spray booms being the common example. The category belongs to the individual aircraft's certificates, so it has to be checked tail number by tail number rather than inferred from the model name.

The listed special purposes include agricultural work, forest and wildlife conservation (which covers dispensing firefighting materials), aerial surveying, patrolling pipelines and powerlines, and a catch-all of other operations that names rotorcraft external-load work. That is why a surplus military helicopter can legally fly a longline at all. The military acceptance substitutes for a civil certification program, and the FAA treats the difference as real: in its 2013 decision on a Firehawk Helicopters petition, it wrote that certification requirements for restricted category aircraft "do not provide the same level of safety" required for Part 27 and Part 29 aircraft.

14 CFR 21.25 Restricted type certificate

The two rules and the misreading between them

The general operating limits for restricted aircraft sit in 14 CFR 91.313. Paragraph (e) prohibits operating a restricted category civil aircraft over a densely populated area, in a congested airway, or near a busy airport where passenger transport operations are conducted, unless a certificate of waiver or special operating limitations allows it. Paragraph (f) then says the section does not apply to nonpassenger-carrying civil rotorcraft external-load operations conducted under Part 133.

Read alone, paragraph (f) looks like an exit: a construction lift carries no passengers and is flown under Part 133, so the populated-area bar would seem not to reach it. The problem is that Part 133 carries its own version of the bar. Section 133.45(d) states that no person may conduct an external-load operation under Part 133 with a rotorcraft type certificated in the restricted category under 21.25 over a densely populated area, in a congested airway, or near a busy airport where passenger transport operations are conducted. Paragraph (f) of 91.313 moves the restriction out of Part 91. It does not remove it from Part 133, where the external-load work is governed.

14 CFR 91.313 Restricted category limits 14 CFR 133.45 Operating limitations

Two provisions in 14 CFR 133.33 close the loop. Paragraph (d), the congested area plan rule, lets an external-load operator work over congested areas only in rotorcraft "type certificated under and meeting the requirements of part 27 or 29," including the external-load attaching means. Paragraph (e), which allows work below 500 feet and closer than 500 feet to people, vehicles and structures, is qualified with the words "except as provided in 133.45(d)." A restricted helicopter is outside the plan provision by its certification basis, and over a populated area it is outside the low-altitude relief as well.

14 CFR 133.33 Congested area plan

Summarized from the regulation text as published on 25 September 2026. The FAA's 2013 Firehawk decision traces the external-load prohibition to a 1977 rulemaking (42 FR 24198, 12 May 1977). The summaries are not legal advice; the operator's Flight Standards office applies the rules to a specific site.

What counts as congested

The regulations do not define "congested area" or "densely populated area," and the gap has practical weight. In a petition the FAA decided in 1999, the New Hampshire operator Joe Brigham, Inc. told the FAA that congested area determinations had varied among FAA regions and were made case by case, and that it had been refused approval for operations in areas it did not consider congested. The determination belongs to the Flight Standards office responsible for the area, which means two similar sites in different districts can be treated differently.

Vertical Magazine reports that FAA inspector guidance in Order 8900.1 describes contingency plans that allow a congested area to become an uncongested one by controlling access to the site, which can open a site to a restricted helicopter. The same report quotes Ken Krauss of Blackhawk Helicopters saying he moves his aircraft to most job sites by truck and trailer to satisfy local offices, which keeps the aircraft off the airways and away from populated areas between jobs. Both approaches cost schedule and mobilization money, and neither is available where the set point itself sits in an occupied block that cannot be cleared. A downtown rooftop is the clearest example.

For planning, the useful question is whether the responsible office will treat the lift site and the flight route to it as congested. If the answer is yes, a restricted helicopter is out regardless of its capacity, and the job needs a standard category aircraft working under an approved plan of the kind described in the external-load operations guide.

The exemption record

Operators have asked the FAA to set 133.45(d) aside for their aircraft, usually offering a congested area plan and additional conditions in exchange. The public record shows the same answer each time.

Compiled from the FAA decisions published in regulatory docket FAA-2022-0998, which contains Denials No. 19439, 10742 and 6934. Denial No. 8137 is known from the FAA's description of it in No. 10742. The table covers decisions located for this article and is not a complete search of every petition filed.

The FAA's reasoning has stayed consistent across 23 years. In the 1999 decision it wrote that "the civil rotorcraft certification process itself provides the FAA with a measure of the level of safety such an aircraft possesses," and that the petitioner's helicopter had not gone through that process, so a congested area plan could not establish an equivalent level of safety. It added that whether restricted helicopters should work over congested areas at all is a question for general rulemaking with public comment, not for individual exemptions.

The Brigham petition shows the commercial pressure behind the requests. The company flew three Bell 206 helicopters certificated under Part 27, each limited to 1,000 pounds on the hook, and bought a restricted UH-1B certificated to lift 4,500 pounds, which it voluntarily limited to 3,000, because rooftop air-conditioning units regularly exceeded 1,000 pounds. It told the FAA that no Part 27 or Part 29 helicopter in New England could lift 3,000 pounds. The denial left the capacity gap in place.

The Firehawk decision settled a narrower point that still comes up. The petitioner argued its S-70s were new-production aircraft built under a Sikorsky production certificate, maintained under a factory program, and referenced Part 29 in their type certificate data sheets. The FAA answered that the S-70 holds a restricted type certificate under 21.25(a)(2) on data sheets H3NE and H5NE, carries a restricted special airworthiness certificate, and was not type certificated to Part 29; the Part 29 reference applies only to later modifications not approved by the Army. New production does not change the category.

Which aircraft remain eligible for an urban lift

Eligibility follows the certificate, not the airframe family. The Chinook shows it most clearly. Vertical Magazine reports that the Columbia Model 234 was certified to civilian transport category standards, with a cargo hook rated to 25,000 pounds, while Columbia's CH-47D holds a restricted type certificate issued in 2014. Two tandem-rotor helicopters of similar size and power fall on opposite sides of 133.45(d). The civil Chinook profile covers the differences between the two in more detail.

Model-level classifications. An individual aircraft can differ, for example a standard airframe converted to the restricted category for a special purpose, so the airworthiness certificate of the specific tail number controls. Eligibility means only that 133.45(d) does not bar the aircraft; each operation still needs an approved congested area plan and the Flight Standards office's approval. The Erickson S-64 is omitted because its classification by variant was not verified against certification records for this article.

The K-MAX appears in the eligible column because Kaman certified it as a new civil design. The EASA type certificate data sheet lists it as a small rotorcraft in the normal category, FAA certificated on 30 August 1994 against Part 27. The same split runs through the Huey family: a civil 205A-1 holds an ordinary type certificate, while a surplus UH-1H of nearly identical appearance is restricted, a distinction the Bell 204 and 205 profile traces model by model. The K-MAX profile covers its external-load design and published hook figures.

What the limit means for planning an urban lift

The practical effect is a capacity gap in populated places. Many of the heaviest civil hooks in the country, including the surplus CH-47D and Black Hawk fleets, sit on restricted aircraft, and 133.45(d) removes them from occupied sites. What remains for a congested set point is the standard category fleet: light and medium singles, the K-MAX, civil Bell mediums and a small number of transport category heavy aircraft such as the Model 234. A pick that fits one of those aircraft at the site's density altitude can be planned normally. A pick that only a restricted type could carry has to be split into lighter pieces, moved to a controllable site, or handed to a ground crane, the comparison worked through in when a ground crane is the better choice.

Two checks follow from that. First, confirm the category of the specific aircraft named in the proposal, from its airworthiness certificate, and not from the model name or a fleet list. Second, when a coordinator arranges the lift, the certificate check follows the named flight operator: its Part 133 certificate, its approved load classes and the aircraft it intends to fly. The Part 133 explainer covers the operator certificate and load classes, and those checks run alongside the category question.

The restriction has seen one recent change on the passenger side, not the external-load side. Section 360 of the FAA Reauthorization Act of 2024 directed the FAA to write a rule allowing firefighters to ride aboard some restricted category aircraft during wildfire work. Vertical Magazine reported that the language excludes aircraft manufactured for and accepted by the US military, which leaves out most surplus Black Hawks, and that the FAA had cited "discrepancies in the aircraft certification basis" as its concern. The provision does not amend 133.45(d). For an urban construction lift, the rule that decided the Brigham petition in 1999 is still the one that applies.