UFM-13 Microlight; Certification Specification 'CS-VLA' and/or 'CS-22'?

[UFO-flying-Airbus]

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" (http://aeroklubuo.macroware.cz/Lambadaen.html)

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/read/30165018/ufm-13-a-2-2009-advanced-composite-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 :O

EASA CS-22(Sailplanes and Powered Sailplanes)
https://www.easa.europa.eu/sites/default/files/dfu/CS-22%20Initial%20issue.pdf

EASA- VLA (Very Light Aeroplanes)
https://www.easa.europa.eu/sites/default/files/dfu/Easy%20Access%20Rules%20CS-VLA%20%28Amendment%201%29.pdf

[patowalker]

The Type Certificate (http://www.laacr.cz/SiteCollectionDocuments/TP%20ULL%20Certifik%C3%A1ty/98_21-98_UFM%20-%2011,%2013%20Lamb%C3%A1da.pdf) was issued by the Czech LAA. In the absence of any mention of any other certification, I assume the aircraft meets Czech UL-2 airworthiness requirements. Whether certain components were tested to higher standards is probably immaterial from a regulatory point of view. You could write to the LAA CR to find out though.

The original mandatory bulletin and a description of the accident that prompted it is here (http://www.laacr.cz/SiteCollectionDocuments/bulletiny/bulletiny-nove/bulletin_laa_04_2009.pdf).

The Czech LAA (https://en.laacr.cz/default.htm) website mentions that "the tests are carried out by the manufacturer under the supervision from the LAA''.

[UFO-flying-Airbus]

Hi Patowalker,

Thanks for your reply. Much appreciated.

[patowalker]

You are welcome UFO.

Just in case it is of interest: I had a repair to my Eurostar done in the Czech Republic and the (UK) LAA accepted a sign-off by an Evektor engineer (also LAA CR inspector), so I could fly it back to the UK and have it inspected here.

It might be possible to get the Czech LAA to accept the Lambada repair to be signed off by a UK inspector, so you can remove the speed restriction.

[UFO-flying-Airbus]

Hi Patowalker,

Very good idea. Unfortunately they (Distar) told me that 'we will not allow anybody to do that, you must send the tailplane here'.

and regarding the Vne restriction the IAA are very strict on ensuring that the Manufacturer's Service Bulletin is followed. So the 73 knot restriction stands if I'm to have a valid Permit, alas.

To reinstate the original 108 knot Vne requires a structural reinforcement of the tailplane which I'm given to understand costs at least 4,000 EUR. Which is absurd because, as I mentioned, the aeroplane has flown at 103 knots IAS previously as I've seen so I am just going to get this minimum work done on the elevator hinges and I'm good to go

Eurostar is a nice plane. I know the dealer here :-)

[patowalker]

Ah, sorry, I read your location as Luton and assumed you were in the UK and the Lambada had an LAA permit. It is a great shame to have such an aircraft restricted to 73 knots.You could justify the cost of the repair by convincing yourself it will be recovered the day you come to sell. :-) Hard to swallow though, as you have already paid for a 108 kt aircraft.

Yes, I am very happy with my Eurostar SL.

[UFO-flying-Airbus]

Hi Patowalker,

My fault- I didn't realise my location was set to Luton (to where I commute for work). But the aeroplane is back home in Ireland. Thanks :-)