cables to a vibration meter. The vibration meter indicates the total
amount of engine movement in mils, one mil being 1/1000 of an inch.
Meter indications are recorded on an Engine Vibration Test Data
Sheet, shown in figure 3.4. The recorded figures are compared with
the figures shown in parentheses on the data sheet for maximum
permissible engine vibration. If these maximum figures are exceeded,
the cause of the excessive vibration must be found and corrected
before the engine can be accepted for flight.
To check the exhaust gas temperature (ECT) system when
periodic maintenance inspections are required, or to troubleshoot the
system if abnormally high or low temperatures are noted, the jetcal
analyzer shown in figure 3.5 is used.
When checking the engine exhaust gas temperature (EGT)system,
the jetcal is used to heat the thermocouple to the desired
temperature without running the engine. The portable jetcal analyzer
is equipped with a handle and two rubber wheels for easy movement.
The jetcal operates on 95 to 135 volts, 50 to 400 cycles ac power
SCHEDULED AND SPECIAL INSPECTIONS
Gas turbine engines are inspected at regular intervals
scheduled. The inspection requirements are stated in a required
order to assure that defects are discovered and corrected before
malfunctioning or serious trouble results.
A special inspection is required whenever any of the operating
limitations have been exceeded. Table II is a list of some of the
conditions when a special inspection is required.
ARMY SPECTROMETRIC OIL ANALYSIS PROGRAM (ASOAP)
In the ASOAP program samples of used oil containing
microscopic metal particles are sent periodically to an oil analysis
laboratory. There the oil and its metal particles are burned by an
electric or gas flame. The wave length of the light emitted from the
burning oil and metal particles is measured to determine the kind and
quality of metal in the oil. The identification gives advance
warning of excessive wear on particular engine parts, thereby aiding
in preventing inflight engine failures.