Flight Manual Revision for Spins (Technical Note No. 23)
The United States Air Force conducted an extensive flight test program to evaluate the stall, poststall, and spin characteristics of the Model ASK-21. The Air Force concluded that the stall and spin characteristics of the ASK-21 were satisfactory and similar to those of other high performance sailplanes. The Air Force did have the following safety findings: The current ASK-21 manufacturer’s flight manual provided by the manufacturer does not accurately document the spin susceptibility. Additionally, the manual does not adequately document the stall and spin characteristics. Alexander Schleicher has developed a revision to the Flight Manual incorporating recommendations from the Air Force flight test program in Technical Note No. 23. For your information, LBA AD 91-112 and Alexander Schleicher Technical Note No. 23, with the applicable revision pages, are included. The FAA highly encourages you to comply with this section of Technical Note No. 23.
Source:
SAIB ACE-98-07