pdf Gfa ad 341 issue 1 Popular

CORRECTIONS TO AIRSPEED LIMITATIONS

Applicable to the Pilatus B4 gliders all models all serial numbers. When the Pilatus B4 glider was Australian Type Accepted in 1973 the manufacturer supplied Position Error data based on flight testing dated 1972. During 1973 further flight testing was completed but the results of those tests were not apparently passed on to the Australian Dept of Aviation. The original Certificate of Airworthiness issued by the D of A called up airspeed limitations appropriate to the position error data they received dated 1972 resulting in significant differences between the Pilatus B4 flight manual airspeed limits, the cockpit placards and the C of A limits. Those differences were highlighted in 1980 when GFA acting on advise from the D of A circularized all Pilatus B4 owners advising them of the Australian certified speed limitations suggesting that the Flight Manuals and the cockpit (IAS) placards should be changed (increased) to match the C of A values. Following a flutter incident involving a Pilatus B4 early 1988, GFA requested the manufacturer to verify the certified Position Error for the type to ensure that we were operating the B4 inside the correct flight limitations. (IAS) The manufacturer supplied the GFA with data dated 1973 which confirmed both that the D of A. C of A. values and the values circularized to owners in 1980 WERE ALL INCORRECT ALLOWING THE B4 TO BE FLOWN OVER ITS DESIGN LIMITS IF THE PILOT FLEW IN ACCORDANCE WITH THE AUSTRALIAN RECOMMENDED PLACARDS.