> Does anyone know whether the aft interior (non cockpit) area
> of the fuselage in the Mono has positive or negative
> pressure? (or Neutral?) In simple terms, is air exiting or
> entering from the flap/trim tab fusulage slots?
The pressure in the aft fuselage area of N135TD (a monowheel XS) is
considerably higher than the pressure in the cockpit. We had quite a
cold breeze on the backs of our legs in the winter, due to air coming in
through the aileron torque tubes. This was accompanied by an elevated
level of carbon monoxide, which was higher in the vicinity of the
control stick pivots. Theorizing that the high pressure under the wing
would force air in through the flap drive slots, we fastened a strip of
baffle seal (the sort shipped with our engine kit) to the bottom surface
of the inboard end of each flap. This seals the gap between the flap
and the fuselage, preventing ingress of exhaust gas (particularly on the
port side), which eliminated all detectable carbon monoxide.
Although the exhaust no longer gets in, we still have air flowing from
the aft fuselage into the cockpit. The excellent leather stick boots
---From Mr. Leatherman have eliminated the breeze on our legs, but we get a
steady flow of air out through the slot for the landing gear lever, even
with the fresh air vents closed. The flap hinge slots on the belly are
sealed with the fairings from the factory speed kit, which leaves the
small openings in the bulkhead at the rear of the wheel well, the flap
drive slots above the wings, and the trim tab slots at the tail. We
don't know what is happening at any of these locations.
Dave DeFord
N135TD
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