The following, provided by Ian Watson of BARC, is an extract from a recent Scrutineers news sheet:
The use of Frontal Head Restraints
There is bound to be talk about the use of Frontal Head Restraints at the moment. HANS is a brand name applicable to a particular design of FHR, and is the one most will be familiar with. Some harnesses are marked as “HANS use only”. As previously advised, such harness can be used with any FIA-homologated FHR device. Although there are harnesses marked this way, it is not mandatory to use a “HANS use only” harness when using an FHR. A normal FIA-homologated harness fitted with 3 inch shoulder straps can be used, and many competitors do so. A “HANS use only” harness, though, can only be used in conjunction with an FHR.
MSA regulations require that where it is mandated, the FHR is FIA-homologated. The HANS device comes in 3 different widths each with 5 different angles, so there are 15 varieties and what may be correct for one driver in one car may not be correct for the same driver in another car. There is also an adjustable HANS device. In addition to checking the unit for cracks, webbing for signs of fraying etc., check that the adjuster mechanism is sound. The Simpson Hybrid device is sized by the chest measurement, and the angle of driver seat recline does not affect the operation of the device.
Shoulder straps should make an angle of 10° to and below the horizontal. The mounting points equally disposed about the users centreline, and such that the straps are positioned to firmly engage with the FHR. The minimum is a four-point harness and – as with any harness – the straps must be pulled tight.
Helmets are to be equipped by the helmet manufacturer – or their agent – with FIA-homologated fixation points. Some helmets are specifically identified to be suitable for use with an FHR. Tethers are to be adjusted in accordance with the manufacturer’s instructions.