Page 24 - August 2015 Volume 9, Number 8

...two things: First, add one more pitot-static malfunction into your storage bin of facts: The effect of introducing pressurized cabin air into the static lines. Second, know your magic numbers.
So there I am, thorough post-maintenance pre- flight complete, all system run-up checks complete, departing for the short hop to my home base. All seems normal ... rotate, gear up, and pitch for the normal 10° initial attitude.
Hmmm, why is my airspeed so low?! Yes, the copilot’s indicator is also reading low. We’re down to 80 KIAS and it is decreasing rapidly. Let’s recheck attitude – 10°, check – and recheck power – torque near redline, propellers still a maximum speed, check – so the IAS has got to be reading incorrectly. It was about now that my scan revealed that both altimeters were reading just a little above the departure airport’s elevation. I estimated I was about at pattern altitude, pulled power
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shop next with its “hell hole” door open. See that round fitting with the hole in the middle, below the outflow valve, almost touching the bottom fuselage skin? Yes, that’s the end of the alternate static air line.
I now want you to think about a failure that was never discussed back in private pilot ground school and, unfortunately, perhaps has also been overlooked during your Initial and recurrent King Air training sessions. As you probably know, down near floor level on the right sidewall in the cockpit, there is an upholstered panel providing maintenance access to two or three static air line moisture drains. Although I have yet to find a mechanic who has ever seen water drip out when they are opened for one of the phase inspections, nevertheless that is their purpose and they are located at the low points in the lines. Suppose that the mechanic got distracted or called away and forgets to close the drains. Now what?
This exact scenario happened not once, but two years in a row, when I went to pick up my company’s old C90 from a well-respected shop in California! In their defense (They still should not have made the mistake!), the drain valves on this 1972 model were rather unusual in that the valve “handle” was positioned parallel with the tube when the drain was closed and perpendicular to the tube when open ... just opposite of what one would normally expect.
SEPTEMBER 2015
KING AIR MAGAZINE • 23