I was just reading through the POH of a DHC-6-100 Twin Otter and was surprised to read the following:
3.8.2 LOW PRESSURE - OTHER SYSTEMS. The airframe deicing system and the autopilot are operated by bleed pressure. In the event of a low pressure condition, a caution light on the caution lights panel will illuminate. Under these conditions, the pressure may be restored as outlined in paragraph 3.8.1. However, if increasing engine speed does not rectify the condition, the use of the autopilot and de-icer system should be discontinued.
I understand why the deicing system is using bleed air, but why is the autopilot powered by bleed air? How does this autopilot work?
The following question is somewhat related:
but it never mentions anything powered by bleed air.