T.O. 33B-1-15-85detected 2 feet away, and a leakage rate of 10 std cm3/s can be detected 20 feet away. Larger leakagerates can be detected at even greater distances. For most cases, 0.1 std cm3/s is the minimum detectableleakage rate.c. The ultrasonic leak detector is used also with a contact probe. This probe is placed on the test assemblyand is used to locate internal malfunctions, such as internal bypassing of hydraulic actuators andleaking valves. Under certain conditions, this probe can also be used for detecting incipient bearingfailures in rotating equipment. However, extensive calibration is required; and this application(detecting incipient bearing failures) is not generally practical for field use.d. Typical applications for the ultrasonic leak detector on aircraft systems include locating leaks duringfuel system pressurization tests, locating leaks in bleed air and air conditioning systems, and identifyinginternal leaks in hydraulic system.5.6.2 Equipment.a. The ultrasonic leak detector consists of the instrument, a set of earphones, two probes, and a rubberprobe extension. The ultrasonic energy detected by the probe is converted into audible signals by theinstrument. These signals are heard by way of a speaker on the face of the instrument or earphonesplugged into the instrument. The earphones are used in noisy locations. The received signals are alsoindicated on a meter on the face of the instrument. A volume control on the instrument adjusts thesensitivity.b. Complete details on one type of detector including calibration and maintenance procedures arecontained in T.O. 33D9-84-30-1. Technicians should check the maintenance and testing proceduresoutlined in the specific technical order/manual for the particular model being used.5.6.3 CalibrationandTesting.Equipment set up, calibration, and maintenance shall be performed in accordance with the equipment manual. Thefollowing is an example calibration. The calibration and equipment checking procedures given in the following areintended to be performed by the equipment operator. Figure 5-81 is an example of an inspector doing leak testing.Figure 5-81. Leak Testing
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