Hello there,
Would anyone be able to kindly tell me what Certification Specification (CS) the UFM-13 'Lambada' motorglider was built to? I am the owner of one of these aeroplanes.
The aircraft was originally built by "Urban Air Sro" (now defunct) in Czech and now "Distar Sro".
The original Urban air website states that "..The load test program was based on the Czech UL-2 regulations, however, due to the aircrafts high performance, several tests were carried out to the more demanding standards of JAR-22 and JAR VLA. Specifically wing gust loading and undercarriage load tests, among others, were proved at the higher standard..";
http://aeroklubuo.macroware.cz/Lambadaen.htm"
It seems to me that that sentence contains some ambiguity.
Was the wing gust loading and undercarriage load test proved to
JAR-22 or JAR-VLA or both or a combination thereof? And what 'other' tests were done to which 'higher standard(s)'? The AFM only refers to its compliance with the Czech LAA's 'UL-2' Certification standard.
I'm interested to know this because the aircraft has been the subject of Mandatory Bulletin requiring the reduction of the Vne from 108kts (200km/h) to 73 kts (135 km/h);
https://www.yumpu.com/en/document/re...osite-aircraft
That was due to aerodynamic flutter of the elevator which lead to two crashes in 2009.
I would like to know which of the two standards were used with particular respect to V speeds as they relate to aerodynamic/structural characteristics. Eg
Va, Vc, Vne, Vd /Vdf etc.
Because CS-22 and CS-VLA are quite different. It would be nice to know how the plane was tested and to what speeds it was test flown (Vd or Vdf if lower).
I can say that at least one limiting speed is not from CS-22 and that is the airbrake limit speed which "..
should include the extension of airbrakes at speeds up to 1.05 VNE". The Lambada's airbrakes are connected to the flap lever and only deploy after the lever has be raised to drop the flaps. Then, when the lever is raised still further, the airbrakes deploy. Since the Vfe is only 59 kts (110 km/h) and the Vne (originally) is 108 kts it means it clearly does not follow that requirement.
My aircraft has flown to 103 kts IAS (ie 5 knots below the original Vne) in calm air. Then the Bulletin came out and that is now restricted to 73 kts.
Any information would be greatly appreciated
Best regards,
UFO-flying-Airbus
EASA CS-22(Sailplanes and Powered Sailplanes)
https://www.easa.europa.eu/sites/def...al%20issue.pdf
EASA- VLA (Very Light Aeroplanes)
https://www.easa.europa.eu/sites/def...ent%201%29.pdf