After installation & reinstallation/Major maintenance of components it may be necessary to carry out adjustments to micro-switches, limiters, sensors...etc and to ensure the correct operation of warning devices and instrumentation, also operating systems will need to be tested to check for correct operation. This is generally referred to as functional testing.
All system functional tests will be specified in maintenance manuals and these must be always done in accordance with maintenance manuals(IAW MM) . Prior to any functional tests, it will be necessary to inspect the system(s) to be operated, this inspection should generally cover the followings,
- Quality and completeness of the maintenance task requiring a functional test.
- Checking of reservoir levels.
- Checking of accumulator pressures.
- Applying external gas pressure to reservoirs, if required.
- A thorough check of the area around services to be operated, to check for clearance,FOD, tools...etc.
- Correct connection of appropriate power sources (electrical and hydraulic).
It should be noted that the specific tests applied to particular aircraft and systems will be stated in the maintenance manual and all the steps must be done in accordance with the Manual only.
Functional tests are designed to test for correct sequence and speed of operation. Usually, if a major component replacement has taken place the system will be operated at low pressure/slow speed, to ensure correct operation before the full pressure/flow tests. During these tests all aspects of the system operation will be tested, this may include the timing of the operating sequence. The results of the functional test as Sluggish, slow, erratic operation or high temperature of fluid during operation gives indications of the faults in the system such as Aeration,Internal Leakages....etc. where it may cause the further inspection of the maintenance job.
