CS 31HB.28 Tethered flight loads

ED Decision 2009/005/R

1. The effects of the loads associated with tethered flight on the balloon’s components (particularly the burner frame/load frame) and any additional equipment (if required) must be considered in the design. (See AMC 31HB.28(a))
2. The tethered restraint system must be designed so that any single failure will not jeopardise the safety of the occupants, the balloon and or third parties.
3. The landing load factor and factor of safety for suspension components must be used for tethering-specific components forming part of the primary load path (e.g. forged rings, v-bridles). (See AMC 31HB.28(c))
4. Operational limitations, associated to tethered flight, must be established and recorded in the Flight Manual. (See CS 31HB.81(b)(2))

ED Decision 2009/005/R

Due to the complexity of tethered flight loading, a simple analysis using configurations based on industry best practice (e.g. 'restraints/tether lines in a “flat tripod” configuration with upwind and downwind v-bridles) can be used to determine the suitability of a design.

Note: The greatest danger during tethering is if any element of the tethering equipment should fail with insufficient positive buoyancy for safe free flight. For this reason single point/single element tethering should not be considered.

ED Decision 2009/005/R

An appropriate factor of safety is CS 31HB.25(a) for metallic components or CS 31HB.25(c) for non-metallic or fibrous suspension components.

→ CS 31HB.30