Posted 1/24/2019, reposted 1/30/2019:
Control Cable Update
ABS will be making recommendations once we have a better handle on the data. For now we suggest having your mechanic remove the safety wire and visually check the turnbuckles, with replacement if there is any sign of fatigue cracks or corrosion. The airplane rigging is not affected as long as the turnbuckle is not turned. Of course the turnbuckle must be re-safetied after inspection.
So far this issue has only been found in aileron cable turnbuckles in Bonanzas, at the point the cable passes under the heater duct. This leads to speculation—not confirmed at this point—that condensation from that duct may promote corrosion on the turnbuckles underneath. If this is indeed found to be a factor, this would confine this issue to Debonairs and Bonanzas, but exclude Barons and Travel Airs. It might also suggest mitigation’s besides cable replacement to address the hazard. However, at least one of the five known cases at this point involved a fatigue failure of the turnbuckle at mid-shaft with no evidence of corrosion.
We’re not yet certain precisely when the change occurred, but approximately 1984 Beech began using a clip instead of safety wire design. In these airplanes the turnbuckles are in the wheel wells, not in the fuselage under the heater duct. These can be visually inspected without removing clips.
We simply do not have enough data yet to make any specific recommendation other than visual inspection and replacement on condition if needed. In part this is because we are waiting for data from the NTSB that will only be forthcoming after the US Federal government shutdown. ABS will provide updates as we learn more.