This SAE Aerospace Recommended Practice (ARP) provides the user with standardized guidelines for the measurement of effective intensity of strobe anticollision lights for aircraft in the laboratory, in maintenance facilities, and in the field. A common source of traceability for calibration of the measurement systems, compensation for known causes of variation in light output, and recommendations which minimize sources of errors and uncertainties are included in this document. Estimates of uncertainty and error sources for each class of measurement are discussed.

Purpose:

This document recommends the test methods and equipment necessary to perform photometric measurements used to determine the effective intensity of red and white strobe type anticollision lights for aircraft.

Limitations:

This document does not include the measurements of long duration flashes, such as those achieved with rotating beacons or flashed incandescent lamps. This procedure does not apply to light sources where the flash duration is longer than 0.2 s. The measurement of long duration flashes and the iterative calculation process required to determine the effective intensity from the intensity-time curve is discussed in FAA Advisory Circular 20-74. Measurement of the effective intensity of bursts of flashes or multiple closely spaced flashes is not included in this document.

Categories of Test:

The measurements are divided into three categories. The categories in descending order of accuracy and detail are:

a. laboratory measurements

b. maintenance facility measurements

c. field measurements

Test Considerations:

Photometric calibration traceability for each type of measurement is recommended. The uncertainties of the measurement system, causes for variations in intensity of the lights, and sources of error for each type of measurement are reviewed in Appendix H. Particular attention is given to the effect of temperature on the transmittance of red glass. In the laboratory test section, a procedure is outlined for compensating for this temperature dependent effect when making intensity measurements.

Safety:

Observe the following safety recommendations when working with strobe based anticollision light systems:

CAUTION: EXPLOSION HAZARD ! Do not operate the strobe light without the fitted lens securely in place. Always wear eye protection when testing strobe lights. The flash tube is under pressure, and possible injury can occur if flash tube explodes.

CAUTION: HIGH VOLTAGE ! Use care when handling cables, power supply and strobe lights during test, as high voltage is present. Allow adequate time for voltage to bleed off or manually discharge the system.

CAUTION: HOT SURFACES ! Do not touch the strobe light during or immediately after operation, as surface temperatures near the lamp may be hot enough to cause injury.

CAUTION: INTENSE LIGHT ! Do not look directly at strobe light during operation as eye injury could result. Use protective eyewear, or assure that the light is properly enclosed within the test compartment.