SEA96FA214 · Mudry CAP 10B

During recovery from a left hammerhead stall, the pilot of a French-built Mudry CAP 10B transmitted that he had a locked control. At about that time, the airplane entered a steep right bank and began descending. It remained in a descending turn for three steeply banked 360 degree right turns, then it impacted the ground. Videotapes revealed rudder and elevator movements during the descending turn, but no aileron movement was seen from the time the pilot said he had a locked control until the airplane hit the ground. Investigation revealed two three-wire electrical bundles in each wing, which had been routed to the wingtip strobe lights and the wingtip smoke canister activation system. These created a resistance to movement of the aileron pushpull tubes. The right wing wire bundles had been routed through the center of the right aileron bellcrank mechanism. Testing revealed that the wire bundles in the right wing could become lodged in the bellcrank mechanism, and could jam the ailerons in a position that would cause the airplane to roll to the right. Flight tests simulating this condition in another CAP 10B confirmed that the airplane was not controllable when the ailerons were jammed in such a position. The manufacturer reported that the 1975 model airplane was not equipped with strobe lights or a smoke canister system when it left the factory. The investigation did not determine who had routed the bundles through the right bellcrank or for how long they had been in that location.

Verbatim NTSB analysis and probable cause from the NTSB dataset