I beg to differ. Every other glider operates on an hours limit.
There are K21s in the UK - living identical 'up-around-down' existences as the Air Cadet Vikings - which are running north of 12,000 hours. There are Twin II Acros with north of 6,000 hours.
With a life limit of 27,000 launches, the Vikings will be completely life-expired at around 2,700 hours. Identical civilian examples won't even be ready for their first life extension at that point. Indeed the relevant TN from Grob explicitly
includes the Viking serial numbers in its life extension to 12,000 hours. Yet somehow they have had a completely nonsensical maximum number of launches imposed on them.
The life extension work is not especially onerous, but is a fairly involved process of cutting holes in things, replacing things inside the hole, then making the hole disappear. Work that could probably be very well undertaken during a recovery at a glider repair facility. Alas the RAF evidently do not trust the manufacturer of their aircraft and, with no life extension programme forthcoming from the Viking TC holder, they are probably returning to service with surprisingly little life left. (RAF-imposed life, that is. The gliders will be good for decades to come in the real world).
Originally Posted by
Mechta
A typical Viking flight is about six minutes. Significant loads on the airframe come from the top of the winch launch, and landing and retrieve on rough ground. Soaring flight on the occasions that it occurs is unlikely to impose large loads, so basing the life on the number of launches is more meaningful.