malfunction based on facts and deductive reasoning.
evidence of leakage, looseness, security, material
Usually the trouble can be pinned down to one or two
condition, and proper installation; and servicing when
areas. By checking each individual area or component,
applicable.
the trouble can be isolated.
2. Conduct an operational check. The mal-
5. Locate the trouble. This step is used to
functioning system or subsystem is checked for proper
eliminate unnecessary parts removal, saving time,
operation. This may be done by using special support
money, and man-hours. Once the AME has isolated the
equipment such as the environmental control test set or
trouble to a certain area or component, a closer
by using aircraft power and equipment with the engine
observation of the valve or component in operation
running. Each aircraft maintenance manual provides
should provide some obvious indication that it is not
the steps to be taken in performing the operational
operating as specified in the MIM. If all evidence
checkout of all the aircraft's systems. The operational
indicates that the problem is electrical, the assistance of
checks and troubleshooting charts for each system are
an AE should be requested.
numbered so that when a malfunction occurs during a
step in the operational checkout, the malfunction can be
6. Correct the trouble. This step is performed only
located under the same step number in the
after the trouble has been definitely pinpointed and
troubleshooting chart. The troubleshooting chart will
there is no doubt that the AME's diagnosis is correct.
provide a list of possible causes of the malfunction in
Removal and replacement, or repair of the unit or
the order of probability, along with a recommended
system is done using the instructions provided in the
remedy. In any case, the AME must check the system
applicable aircraft MIM.
out thoroughly, observing proper operation, sequence
NOTE: While performing maintenance on any
of events, etc.
system, ensure the step-by-step procedures outlined in
3. Classify the trouble. Malfunctions usually fall
the MIM, including cautions, warnings, and safety
into three basic categories--electrical, mechanical,
notes concerning the specific procedures, are strictly
and/or improper installation. Using the information
complied with.
acquired in steps 1 and 2, the AME determines under
7. Conduct a final operational check. The affected
which category the malfunction occurs. Proper use of
component or system must be given an operational
the test set or multimeter will identify whether the
check following installation or repair to verify proper
trouble is electrical or mechanical. Use of the MIM
system or component operation. The MIM will provide
when performing all maintenance tasks should prevent
the procedures for conducting the operational check. It
improper installation. Something affecting the flow of
will usually require operation of the system in various
gas or liquid (as could be the case in a vapor
modes (manual and automatic for air-conditioning and
cycle ACS) could be categorized as a combination
pressurization systems) or through several cycles, as
electrical/mechanical failure. Most mechanical failures
applicable. Specified steps throughout the repair
should be found on the visual inspection; however,
procedure and operational check must be observed and
drive shaft failure is not readily apparent until the valve
certified by a quality assurance representative or a
is operated. In some cases it may even be necessary to
collateral duty quality assurance representative from
disconnect the valve from the ducting so that the
the work center performing the work. These steps are
butterfly valve can be observed through the end
usually identified in the MIM by underlining, italics, or
opening. The position indicator on some valves can
some other obvious method.
indicate that the valve is changing positions, which can
be a false indication if the shaft is broken after the
indicating mechanism, or if the butterfly valve was
Q6-13.
In order for the human body to operate at the
damaged in such a manner that the shaft would rotate
same level of efficiency as at sea level, what
without actually repositioning the valve.
solution was developed?
4. Isolate the trouble. This step calls for sound
Q6-14.
The area of an aircraft to be pressurized must
reasoning and a full and complete knowledge of how
be free from all air leaks. How is this
the system and each component operate. During this
accomplished?
step, the AME can make full use of their knowledge and
Q6-15.
For the S-3 pressurization system, what
the system schematics to trace system operation and
component provides the pressurization
systematically eliminate components. They can arrive
schedule?
at a reasonable conclusion concerning the cause of the
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