Sounds like the sealing of the flap slots against fumes ought to be a mandatory
mod.
Did you experience any real speed increase?
Duncan McF.
>
> 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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