Schempp-Hirth Ventus-3M Performance, Предварительное руководство по эксплуатации самолета

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SCHEMPP-HIRTH FLUGZEUGBAU GmbH, KIRCHHEIM/TECK
Ventus-3M „Performance“ FLIGHT MANUAL
March 2019 CS 22
Revision – 4.5.11
4.5.11 Flying at low temperatures
When flying at temperatures below 0° C (32° F), as in wave or during the winter
months, it is possible that the usual ease and smoothness of the control circuits is
reduced. It must therefore be ensured that all control elements are free from
moisture so that there is no danger of them freezing solid. This applies especially
to the airbrakes.
From experience gained to date it has been found beneficial to cover the mating
surfaces of the airbrakes with "Vaseline" along their full length so that they cannot
freeze solid. Furthermore the control surfaces should be moved frequently.
When flying with water ballast, observe the instructions given in section 4.5.9.
Warning:
For the preservation of a proper surface finish free from cracking, the
manufacturer
strongly advises against high altitude flights with
temperatures below – 20 °C (- 4 °F)!
A steep descent with the airbrakes extended should only be conducted in
case of emergency (instead of the airbrakes the undercarriage may also
be extended to increase the rate of sink).
Caution:
From many years of experience, the polyester finish on this aircraft is known to
become very brittle at low temperature.
Particularly when flying in wave at altitudes in excess of about 6000 m
(approx. 20000 ft), where temperatures below – 30 °C (- 22 °F) may occur, the
gel-coat, depending on its thickness and the stressing of the aircraft’s
components, is prone to cracking! Initially, cracks will only appear in the
polyester coating, however, with time and changing environment, cracks can
eventually reach the Epoxy/glass cloth matrix.
Cracking is obviously enhanced by quick descents from high altitudes with
associated very low temperatures.