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Pitot-Static Check...Repairman CertificateJeff,
The FAA took away an A&P's previlige to do a pitot-static check and altimeter adjustment years ago. Only an avionics repair station and its repairmen may sign off on the pitot-static check according to their ops spec. Having a calibrated box will help you find the problems but you may not sign the check on that basis. You can get the system up to specs, leave everything hooked up and call in the proper personnel to witness the check and run the system up and down. That can save some time and money for you.
Three knots per minute is out of spec and the system is out of spec regardless of whether you have digital, analog or both displays. If what you cannot see on the analog display shows up on the digital display you are simply better seeing what is wrong with the system. Find the leak.
Walter Dodson 1895740 IA
N990Y IV-P
ps: Your repairman certificate is for your airframe and engine only. Avionics still require trained people from a repair station or manufacturer.
pps: Note that a pressurized aircraft must be tested differently than a non-pressurized aircraft.
----- Original Message ----- From: Jeffrey Liegner, MD
Sent: Sunday, April 17, 2005 7:52 AM
Subject: 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 Kts/min and airspeed reading correct. 100 ft/min and altimeter reading correct.
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