pdf Gfa 027an CANCELLED Popular

L-13 BLANIK SAFE LIFE LIMITATION

CANCELLED

Further information has been received relating to extension of the service life of the L-13 Blanik gliders. The receipt of this information from the Czechoslovakian Aviation Authorities has been expedited by personal visits to a number of overseas aviation authorities including Czechoslovakia by Mr C.W Riley at his own expense. It is understood that the limitation of 3000 hours or 15000 launches in service arose at least partly out of the type certification proceedings in the the Federal Republic of West Germany where one requirement for type certification is a safe service life of 3000 hours. The average annual utilisation of 200 to 250 hours in many European countries yields a 12-15 year service life which has been regarded as acceptable. There are three common methods for determining a safe service life: (a) by calculation, (b) by accelerated load cycling in a test rig to stimulate service conditions, and (c) by a study of fatigue damage to aircraft in service. All the above are subject to uncertainties dependent on how closely calculated or assumed conditions conform to the actual 'in service' conditions and variability between aircraft of the same type. Because of these variabilities, a safety factor must be applied to the results obtained by any of the above methods.