Hi Eric

In 1992 the K21 had a TN for service life extension issued that started with inspections at 3000 and 6000 hrs followed with inspection again at 7000 hrs and at thousand hour intervals to a total of 12000 hrs.

As a result of those inspections there was an updated TN in 2003 that had 3 stages.

The 1st stage had inspections at 3000 hrs, 6000 hrs and an increase to fly to 9000 hrs subject to manufacturer approval

The 2nd stage involved inspection at 9000 hrs to gain approval to fly to 12000 hrs

The 3rd stage then requires further inspection along with the total aerobatic hours being 12.5% or less of the airframes hours for Schleicher to decide on releasing the glider for service up to 15000 hrs. At 15000 hrs the inspection is repeated and the glider may be approved for an extension to 18000 hrs.

All in all not a trivial thing and shows the importance of accurate flight time recording.

As more time in service is gained with all types of gliders, not just the K21, further life increases among all types can be expected which is a good thing

As a matter of interest, what sort of hours are clubs out there putting on their trainers?

:-) Colin