The Gueneau (Geno) 316 was in service on almost all types of jets
of the Swiss AF inventory and on "slow movers" like Pilatus P-3, PC-6/ 7/ 9.
The 316 was deemed unsuitable for helicopter operations already at the early stage of its evaluation. This was mainly due to its weight and the longer mission durations for helicopters compared to those for fixed wing aircraft.
Peculiar features of the "Swiss 316", compared to the standard French issue:
Removal of the clear visor (g-depending) lowering mechanism;
Both visors separate locking and adjustment capability;
Limiting the rotation of the helmet’s oxygen masks coupling;
Use of padding inserts of different thicknesses for better fit;
Installation of adjustable neck strap;
Installation of chinstrap;
Replacement of the original communication harness with a SPH-4 one;
Upward pointing headset straps like the ones fitted to the Gueneau 317;
Installation of Cosmetan dark visor;
Installation of boom mike bracket.
The introduction of the 316 was not without flaws. The helmet was considered too heavy.
Additionally, the metal grommets/ eyelets fitted to the helmet had a tendency to scratch the aircraft canopies.
To overcome this problem, a modified version of the helmet, the Gueneau 316 "modifiziert" was implemented.
More on tested and Swiss Gueneau 316 HERE
Right - an early trial to overcome the problems of the Gueneau 316, by appling a leather padding to the top of the shell.
Reportedly this solution was rejected due to the fact the padding blocking the shell's vent holes thus creating problems in case of an ejection.
Note: the above degraded image is taken from the book “In Cockpit für die Schweiz” by Dölf Preisig and Ronald Sonderegger, for educational purposes only in accordance with the Berne Convention, Art. 10.