As far back as 1948 several DC 3 accidents and incidents had been attributed to the Sperry A 3 autopilot.
So much so that at least one leading airline removed their autopilots.
Problems encountered included:
Operating stop of follow up cable fouling controls
Cable detached fouling controls
Pulley seized
Cable return spring broken.
Some operators were in the habit of engaging the autopilot on turnarounds as a 'quickie' gust lock. I even encountered one Brit pilot who engaged it while taxying in extreme winds, such as we often encountered in the Shetlands. Baaad idea.
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