Parachute use in single seat gliders

I have two separate questions about use of parachutes in non-aerobatic and non-contest flight in a single seat glider. First, I understand that it is a good and best practice for cross country flying and of course if it is possible to wear one, why wouldn't you? I'm not intending to fly without a legally packed chute, but I am wondering if it is actually against the regs..

1. First, a straightforward question - Is the use of a parachute *required* in the AFM of all single seat gliders? I know it is assumed, particularly since it functions as your seat cushion in many gliders. And I know contests require them for very good reasons.

I suspect it is required in some gliders as part of the flight equipment but maybe not in others? I'm asking because I don't wear a chute in our trainers and club ships like the ASK-21 or 1-34 but can fly them cross country. When I fly the club Discus, I put the chute on, even if I am flying to the same turnpoints.

2. If a parachute is *not* required as part of the glider's equipment, does that mean that if you do use it for seat cushion purposes only (e.g. no intention of aerobatics in flight) that it must have been repacked in the required 180 days?

Part 91.307 says in part, "No pilot of a civil aircraft may allow a parachute that is available for emergency use to be carried in that aircraft unless it is an approved type and has been packed by a certificated and appropriately rated parachute rigger --" it then goes on to explain the 180 day rule and so on.

Does 'available' mean that if you flew with an out of date repacked chute as a seat cushion but didn't put it on it would be legal?

Again, I understand that the chute should be repacked within the 180 day limit and don't intend to break that. But I have been confronted with an out of date chute in a single seat glider and wanted to go for a local flight. I'd be hesitant to fly without out but It sounds to me like you can't even bring the chute for a seat cushion since it would be 'available' for use in an emergency.