Cargo hook (helicopter)
A cargo hook is a device suspended below a helicopter and allows the transport of external loads during flight. Common terms for this operation include slingwork, underslung loads, external loadwork, and external load operations.
Primary, or "belly" hooks, are designed to mount directly to the airframe belly, i.e. underside, of a helicopter. Because they are attached to the fuselage, or "skin," of the aircraft, belly hooks are regulated by the various worldwide aviation regulatory agencies. In the United States, belly hooks are governed under Federal Aviation Administration (FAA) FAR Part 133. Belly hooks are designed, manufactured, and approved for use on specific aircraft models. Belly hooks that have been certified by the FAA receive a Supplemental Type Certificate (STC) that describes the aircraft models that are authorized to use the hook for external load operations. For example, a belly hook approved for use by the FAA on a Eurocopter AS350 could not be used on a Bell 407 helicopter unless covered by the STC.
For small to mid-size utility helicopters performing external load work, belly hooks are typically mounted to the fuselage using either a sling, or a suspension configuration. The sling mount uses a single attach point, whereas a suspension system uses four attach points. Since suspension systems transfer the weight of the cargo load across a larger swath of the aircraft, they can carry heavier loads than sling mounts.
Remote hooks are suspended beneath the belly hook by a long line, swivel, or other device. Because they are not attached directly to the airframe, they do not require aircraft-specific certification and can be used on a wide variety of helicopter models.
Parts of a cargo hook
Key components of a cargo hook include the load beam, the keeper, and the attach point. The load beam is the solid piece of metal at the bottom of a cargo hook that supports the load. Usually it has a curved, narrow end which is used to load a ring, rope, or net onto the hook. The keeper is the locking, spring-operated mechanism that keeps the load from sliding off the load beam during transport. The attach point attaches the hook to the belly of the helicopter, swing system, or longline.
Helicopters & load capacities
The following table includes a list of helicopter models that are designed to carry underslung loads. Cargo capacities provided reflect the airframe manufacturer's specifications; when put into practice the actual maximum load capacities may be less, depending on the rating of the cargo hook equipment. For example, if a helicopter model is rated by the manufacturer as having a maximum cargo sling load capacity of 4,000 LB, but the cargo hook equipment is only rated for 3,000 LB, then the pilot can only carry loads weighing 3,000 LB or less.
|Manufacturer||Model||Slingload Cargo Capacity|
|Aerospatiale Alouette II||SE 3130, SA 313||2,500 LB|
|Aerospatiale Allouette III||SA 316-319||1,650 LB|
|Aerospatiale/Eurocopter||AS 550/555, AS 355||2,000 LB|
|Aerospatiale/Westland||SA 330 Puma||7,055 LB|
|Bell||206 Jet Ranger/OH-58||4,000 LB|
|Bell||206 Long Ranger||4,000 LB|
|Bell-Boeing||V-22 Osprey||15,000 LB|
|Hindustan Aeronautics Ltd||DHRUVS ALH||3,300 LB|
|MD Helicopters||500||2,000 LB|
|MIL||M-8/MI-17 HIP C-K||6,614 LB|
|MIL||MI-10/MI-10K Harke||36,600 LB|
|Sikorsky||S-64E/F Sky Crane||20,000 LB|
|Sikorsky||S-70/UH-60 Black Hawk/SH-60 Seahawk||9,000 LB|
Utility helicopter operators perform a wide variety of external load work that varies region to region and season to season. Some of the most common external load operations include:
- Fire suppression with buckets;
- Construction work
- Fertilizer spreading
- Christmas tree harvesting
- Electrical line work
- Servicing oil rigs and stocking remote outposts with supplies
- Agriculture (fence building, distributing hay bales, salt blocks, etc.)
- Marijuana Extraction
- Aerial Side-Trimming around power transmission lines and pipelines
- FAA FAR Part 133 "FAR Part 133". FAA. Retrieved 29 December 2011.
- FAA Supplemental Type Certificates (STC)
- McGowen, Stanley S. (2005). Helicopters: An Illustrated History of their Impact, pp 226-296. Santa Barbara: ABC-CLIO, Inc.
- MacDonald, J., Rossnagle, W., & Higgins, L. (2009). Handbook of Rigging: For Construction and Industrial Operations (5th Edition — pp. 543-553). New York: McGraw-Hill Professional
- Homeland Security Committee Approves Bill to Regulate Fertilizer June 15, 2006, ROTORNEWS
- "Helicopter Logging (heli-logging)" FORESTRY.COM, October 22, 2008
- "Tree Culturing & Harvesting," Pacific Northwest Christmas Tree Association 
- Verdecchio, Tom, " " TRANSMISSION & DISTRIBUTION, November 1, 2004 Helicopter Live Work Requires a Safe Platform
- "Helicopter Pilot Jobs: Position Description". AVJobs. Retrieved 18 May 2012.
- "Helicopter External Load Equipment," Rotor & Wing Maintenance
- Heppler, Johnny, "Marijuana Grow Destroyed and 38-Arrested by Washington County Area Drug Task Force," July 17, 2011, KCSG Television 
- "Aerial Side-Trimmer Saw". Haverfield Aviation. Retrieved 18 May 2012.
- Media related to Helicopter hooks at Wikimedia Commons