Why does the DHC-6 have only one set of elevator cables? Air Moorea Flight 1121 crashed because its up-elevator cable broke, allowing the elevator to blow to its faired position and thus be unavailable to counteract the pitch-down moment caused by the flaps being retracted;1 the DHC-6 elevator control system has two cables (up-elevator and down-elevator, distinguished by what part of the aft-quadrant bellcrank they attach to), and, if one breaks, the tension in both is released and the elevator floats.  No redundancy is provided in the form of a second or third set of elevator cables, unlike how most airliners have double- or even triple-redundant flight controls.  Why does the DHC-6 have only a single set of elevator control cables, rather than two or three?



1: No matter that retracting one’s flaps should not do that.
The Twin Otter isn't certified in a category that requires duplicate control runs with split surfaces.  It's more or less a single engine Otter with two PT-6s and a redesigned tail.  Those requirements apply to heavier aircraft than the DHC-6.