Aerobatic Gliders Behave Differently Than Manual Describes in Edges of Flight Envelope

The Zaklady Lotnicze Marganski & Mysowski MDM-1 Fox and MDM-1P Fox P sailplane has seen the issuance of an EASA Airworthiness Directive, warning that the "aerobatic glider" behaves differently in spins from how it presents in the approved Flight Manual.

"Accidents of MDM-1 sailplanes have been reported, where the sailplanes crashed during aerobatic flights," reads the EASA rationale. "The following investigations concluded that pilots did not manage to recover from spin.It has been also determined that, the information about sailplane different response to different ways of entering the spin (it behaves differently in dynamic or "snap" initiation than when a spin is initiated with minimum airspeed), was not provided in the FM This condition, if not corrected, could lead to pilots’ inability to recover from spin, possibly resulting in loss of control of the sailplane."

Thus, the EASA requires a revision to the Fox and Fox P AFM. "To address this potential unsafe condition, ZLMM revised the FM, including, among others, an improved description of sailplane behavior in stall and spin, and amended recovery procedures, and issued the Safety Bulletin, as defined in this AD, which provides instructions for implementation of revisions to the applicable FM."

"For the reasons described above," it continues, "this AD requires amendment of the FM... within 30 days after the effective date of this AD." All flight crews must be informed of the updated AFM. Links to the Service Bulletin that presaged the Airworthiness Directive, as well as an updated Flight Manual, can be found at the manufacturer link below.

FMI:www.mmaviation.pl/en