Page 20 - Dec 2022

The AB and CD circuit pins of the duct sensor thermostat. The CD circuit wasn’t providing a proper reading.
extremely confident in his ability to assess and fly any aircraft. The pilot seemed eager to please the owner by saving him money wherever possible. From what I could see, the gear was due for a six-year inspection at the time of purchase. The shop doing the work did not work on King Airs regularly. After the gear collapse, I was engaged to investigate the cause and I found clear evidence the gear was not rigged properly. This would have been found during a proper pre- buy inspection. Enough said?
Fast forward to the F90 with the gear collapsing – here was my opportunity to solve the mystery of the melted heat ducts. We ohm’d out the duct temp sensor and it checked out good. We went a step further and applied heat to it, as called out in the maintenance manual. There are two circuits in this thermostat. The AB circuit gave a proper reading, but the CD circuit wasn’t reading what it should have been.
My client happened to have an E90 in the hangar, so we decided to test
18 • KING AIR MAGAZINE
DECEMBER 2022