barfield 1811GA Series User Instruction Manual

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barfield 1811GA Series User Instruction Manual Manual pdf 35 page image

56-101-00184 / 00185 Rev. I CH. 3September 24, 2014 Page 23 of 56(5) When the vertical speed reference is no longer needed, close the VERTICALSPEED (#3) control fully (CW).Note: Isolating the VSI at a pressure other than ambient, causes pressure to be“trapped”. As a result in later tests the T/S VSI (#4) could show descent(when paired with the Static System) even though the altitude is actuallyincreasing. Following steps (1) thru (4) listed in this section will ensurethere are no adverse effects to the T/S units.8. COMBINED PITOT (AIRSPEED) / STATIC (ALTITUDE) TESTThe following procedure is valid for equipment such as machmeters, engine pressure ratioindicators, and flight recorders, etc.Note: Perform tests referenced in sections 5. PRETESTS, 6. PITOT SYSTEM TEST,7. STATIC SYSTEM TEST, and Static Leak Test (for non-pressurized aircraft only).Correct any leaks found. Perform the following test in exact order given.A. Combined Pitot / Static System Connection(1) Using the specific aircraft-plumbing diagram, connect the PITOT PORT (#1) to theaircraft pitot system (Hi port) and the STATIC PORT (#6) to the aircraft staticsystem (Lo port).Caution Ensure the test will not harm components in the aircraft system.(2) Close all T/S valves. Operate the PRESSURE PUMP (#16) to develop 10 psi.Operate the VACUUM PUMP (#11) to develop approximately 20 inHg.(3) Verify that the T/S and the aircraft altimeters have baro’s set to 29.92 inHg(1013.3 mb).B. Below Field Elevation TestNote: If there are no altitude tests below field elevation, this test may be omitted.(1) Open the CROSSBLEED (#8) valve fully CCW. While ensuring not to exceed theaircraft VSI full-scale range, gently open the PITOT CONTROL (#19) to reach thedesired downscale altimeter test point. Once reaching the test point, close thePITOT CONTROL (#19) CW and CROSSBLEED CONTROL (#8) valves fully.Note: The airspeed test point may only be set above the normal resting positionof the pointer.(2) Taking care not to exceed the test point, carefully open the PITOT CONTROL (#19)valve until the airspeed (#2) increases to the desired test point.