Gas turbine engines are run in test cells to ensure quality control before they are shipped to the user for installation in aircraft. The test cell is equipped with instruments to monitor engine performance. Engine vibration tests can be performed with the engine in the test cell or installed in the aircraft. Vibration tests are required after any maintenance on rotating parts or when excessive engine vibration is suspected. A jetcal analyzer is used to check the accuracy of the egt system and to calibrate it.
There are two kinds of engine inspections, scheduled and special. Scheduled inspections are required whenever any of the operating limits have been exceeded.
Under the Army Spectrometric Oil Analysis Program (ASOAP) oil samples are analyzed for metal content, to prevent in-flight engine failures.
Personnel performing maintenance on gas turbine engines should observe the precautions stated in the engine manual to avoid serious personnel injury or engine damage. All engine cleaning, both internal and external, should be performed in accordance with the appropriate engine manual. In most cases the engine manual prescribes the approved cleaning procedure to be used. Most engine parts may be cleaned by the vapor degreasing, solvent immersion, or vapor blasting methods.
The TBO of a gas turbine engine depends upon such things as operating environment, mission to be performed, and how will the engine wear as flight time is built up.
Maintenance function assignments are determined by the maintenance allocation chart found in the aircraft -20 manual. Three categories of engine storage are used. The decision as to which category of storage is to be used depends upon the length of time the engine will be inactive.
|David L. Heiserman, Editor||
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Revised: June 06, 2015