Lighting mockups are important, particularly for new configurations or upgrades. They can be costly and time consuming. Much discretion should be exercised in defining the extent to which completeness of the mockup or simulation is required. In aircraft with extensive canopies or windows, control of internal reflections can be as critical as the lighting. The mockup shall be provided with the actual production (or production prototype) lighting equipment and instruments or models of instruments which have lighting that is representative of production lighting insofar as practical, which will afford a reasonable indication of the effectiveness of the lighting involved. Exterior lighting that may impact on interior lighting, viewability, or safety will be mocked up in conjunction with a suitable cockpit mockup. A practical, end-to-end, SYSTEM LEVEL verification test of NVIS compatible interior lighting using Visual Acuity as the measure can be outlined as follows. This test has been useful in determining that a contractor has met his NVIS requirements in a simple, straight forward, and quantifiable way. This test may be used as the sole pass/fail, contracturally required, verification criteria or it can be used with other verification methods as suggested by the Verification Matrix guidance found elswhere in this document.
a. Place aircraft with full-up prototype or pre-production NVIS interior lighting in an environment which is as dark as possible (e.g., a hangar with the doors shut, lights out, at nightime, etc., an engine hush house, etc.).
b. Place a Visual Acquity eye chart(s) a set distance from the nose of the aircraft where the pilot/copilot can see it (e.g., 20-30 feet). Generally these charts have a high contrast (i.e., black on white) square wave pattern on them. Each chart has a different spatial frequency on it.
c. While looking thru the NVGs that will be used operationally, have the test subjects read the charts as if taking an eye test and record their Visual Acuity scores. Do this with NVIS lights ON as one condition and with all lights OFF as the other condition. The canopy should be closed.
d. This test may be repeated thru the HUD & canopy (i.e, straight ahead) and off-axis (i.e., thru canopy alone)
e. Compare the two Visual Acuity scores. If there is a signifigant difference/degradation in Visual Acguity between NVIS lights ON and light OFF, then this may be due to an unacceptable level of NVIS incompatible light. Advise contracturally pre-defining an acceptable, numerical Visual Acuity score.
f. Highly recommend contacting Armstrong Laboratory (AL/HRA) at Mesa, AZ (formerly William AFB), DSN 474-6561, for help with this test.
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