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Pitot-Static Check...Repairman
Certificate
Can the person who holds the "Repairman " certificate
for an experimental plane sign off on the Pitot-Static check, after
confirming perfomrance (below) with a certified "IFR
Box?"
Separate question...if the "IFR Box" is analog and the
airspeed & altimeter in the plane are digital, and the analog
output complies with the regs, but the more precise display shows
bleed down of 3 knots per minute, is this out of specs? Are
their digital vs analog guage rules?
Jeff L
N334P
Test Airspeed and
Altitude
Airspeed and altitude need to be tested
using a Pitot/Static test set for proper indications and values.
Per FAR 43, Appendix E, the aircrafts' Pitot and Static
systems must be tested for leaks anytime a connection in the
associated system has been opened. This is done by applying
pressure and vacuum to the Pitot and Static systems respectively
to a set point and noting the change after one minute with the
test box valves closed. Pitot System
1. Connect the Pitot/Static test set to
the aircraft with approprate hoses and fittings.
2. Open the Pitot and Static bleed valves
to equalize the pressure between the aircraft systems and the ambient
air.
3. Close the Pitot (airspeed) bleed
valve.
4. Open the Pitot pressure valve and
apply enough pressure for the standby ASI and/or the EFIS to
display red line (Vne).
5. Close the Pitot pressure
valve.
6. Start a timer and monitor any leakage
of pressure during one minute.
NOTE: Airspeed should not drop more
than 2 knots in a one minute time frame. If the leakage is
more than 2 knots, tighten all Pitot fittings and test again. Repeat
until pressure drop is less than 2 knots per
minute.
7. After leak test has been verified,
open the Pitot bleed valve and vent the pressure until the Pitot
system has been equalized with the ambient air.
Static System
1. With the Pitot and Static system
equalized, close the Static (altitude) bleed valve.
2. Set the pilot side EFIS baro scale to
29.92 (right knob adjsut).
3. Note the altitude
reading.
4. Open the Static vacuum valve and apply
enough vacuum for the EFIS to display one-thousand (1000) feet above
the starting altitude.
5. Close the Static vacuum
valve.
6. Start a timer and monitor any leakage
of vacuum during one minute.
NOTE: Altitude should not drop more
than 100 feet in a one minute time frame. If the leakage is more
than 100 feet, tighten all Static fittings and test again. Repeat
until vacuum leakage is less than 100 feet pre
minute.
7. Open the Static bleed valve and vent
the vacuum to equalize with ambient air.
8. Remove the hoses and fittings used to
test the aircraft.
NOTE: During the leak tests, the EAU
can be verified for proper airspeed, altitude, and vertical
speed readings. PITOT/STATIC CHECKLIST ? Pitot system leak less than 2
Kts/min and airspeed reading correct. ? Static system leak less than
100 ft/min and altimeter reading correct.
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