SWING - Paraglider - MISTRAL 2.22
SAFETY NOTICE to the DHV 26.02.2003
The following safety notice relates only to the SWING Mistral 2.22 glider.
It has come to the attention of SWING that there have been occasional incidents when this model has shown an increased tendency to deep stall in certain situations. All gliders sent to us for inspection came within the permissible tolerance levels. Nor did these gliders differ in any other respects from the sample provided to DHV.
We are therefore asking all Mistral 2.22 – pilots to take extra care when using their gliders, particularly in the situations described in (a) to (d) below.
All equipment which has been affected so far shows the following unusual behaviour:
1) Deteriorating launch behaviour
2) Stable deep stall, especially when "big ears" are used
3) Poor transition to normal flight after a B stall
4) Shorter braking distance
The following factors can contribute to the tendency to deep stall and were found in almost all cases brought to our attention:
(a) Weather conditions with high air density
(b) Dry air conditions
(c) Flying where the temperature is around or less than 0° C.
(d) Take-off weight is at the lower end of the weight range
(e) On "big ears"
Gliders generally come close to the stall limit in the situations above ((a) to (d)) since in these cases drag values increase greatly. It appears that a pilot could go beyond this stall limit on the Mistral 2.22 in unfavourable conditions.
Materials not at fault:
The problem cannot be put down to defects in the materials (e.g. increased air permeability) since newer gliders with good air permeability values are also affected.
The advice to pilots which is given below on how to check their gliders was determined in agreement with the DHV and should be carried out before the next flight. Further investigations should only be carried out by Swing.
Determine whether the Mistral 2.22 shows any tendency to hang back when launched on a level training area in still conditions (not a reverse launch). This should be tried at least five times before reaching any conclusion.
If it is clear that its launch behaviour is poor or if there are any other peculiarities, the glider should not be flown and SWING should be contacted.
Swing Tel: +49 (0) 8141 3 27 78 88
Reminder: tips on what to do in a deep stall:
- Don't apply too much brake
- Consider using the speed system
- Consider pulling down the A-risers
The Swing Team