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Dynamic WT9 - new procedure for spin recovery

My club has bought a Dynamic WT9 in the LSA version a few years ago, with a certification as a LSA always being on the horizon but not yet achieved by Aerospool. This has been dragging on for a while, and the plane now is (according to what I was told) on a permanent EASA permit-to-fly. But it seems that certification efforts are still ongoing, because our mechanic drew my attention to the Mandatory Service Bulletin SBLSA-012-2016_R0 from November 02, 2016. It states:

SUBJECT: Installation of Ballistic Recure Management System Magnum 601

Change of the emergency procedure for recovery from an inadvertent spin in the Pilot’s Operating Handbook.

REASON: During the TC process it has been discovered that the emergency procedure for recovery from an inadvertent spin is inappropriate. In some configurations the effectiveness of the elevator and rudder may be reduced and the aircraft could enter an unrecoverable spin.

Therefore activation of ballistic rescue system was determined as a standard emergency procedure for spin recovery.
Ballistic Rescue System must be installed on the aircraft to comply with the new emergency procedure.

Our plane already has the parachute installed, so we just need to change the POH as follows:

The WT9 hadn’t been one of my favorite aircraft so far, I find it a bit crammed inside, and it makes my back hurt after 1 hour in the seat. I also wasn’t really convinced about the reliability of the Rotax… but on the other hand it has very good glide performance. So I started flying it a bit more lately, but this SB has the potential to chill my interest.

I have around 90 hours on Cirrus, so I don’t find this spin recovery procedure shocking per se. But I would really like to know more about the effectiveness of the parachute for bringing you down without serious injury. For example, the Cirrus has specially designed front seats that absorb much of the impact, but not so the back seats. It would be interesting to know at what vertical speed you would descend under the Magnum 601 at the MTOW of 550 kg, what g force that would make on impact and how likely this would be to hurt you. I would also like to know if and how the BRS has been tested and what the results were. In the Cirrus, I feel that CAPS is sufficiently well tested that I wouldn’t hesitate to use it if needed. In this plane, I would feel much more like a test pilot and depending on height above ground would probably still want to try the conventional spin recovery method first.

I also think that this is an interesting data point about the value or non-value of certification. This plane has been flying in an ultralight version for quite some time, and I always found it strange to see the LSA certification process drag out for so long. This SB gives a little insight into one of the reasons.

PS: My first post in the “uncertified” category. If they ever achieve certification, it needs to be moved.

Last Edited by Rwy20 at 28 Nov 15:56

Hmm, that’s not very comforting. A plane that cannot be recovered from a spin is no real plane. I fly the ULS version, and no such bulletin exist for it, but ….

LeSving wrote:

Hmm, that’s not very comforting

Well, THAT is what should have been discovered with initial certification, and that is what certification is for.

The cog of the WT9 shifts aft if you load the plane, like so many microlights. Thus, within certification limits of the microlight version, there must not necessarily be harmful spin characteristics. But it shows very clear that it is not “easy peasy” to overload those aircraft without intention to become test pilot in the most unprepared scenarios. There is more than bending spars on the way to higher take off masses…

mh
Inside the sky.
EDXE, EDXF, Germany

mh wrote:

Well, THAT is what should have been discovered with initial certification, and that is what certification is for.

You can do spin tests with no certification, and a whole bunch of other flight test for that matter, like Vans and Sonex does. The WT9 is probably OK at MTOW 450 kg. The added 150 kg for LSA is 33% increase. That’s a lot, and if COG is shifted aft in addition, that surely has to have some effect. IMO, all light aircraft should be recoverable from a spin, and this should be tested.

Video from spin recovery testing is here:


No ballistic parachute to be seen anywhere :-)

LKHK, Czech Republic
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