Abstract :
Almost all commercial aircraft use an Auxiliary Power Unit (APU) for flight
operational energy sources. The APU produces energy in the form of pneumatic and
electric which can be used for components and systems on aircraft. Aircraft
performance will be disrupted if the APU cannot reach 100% speed on time (line up
slowly). If the temperature in the oil increases unreasonably, the APU will also be
disrupted and will lead to auto-shutdown. So the aircraft will experience difficulties
in obtaining pneumatic and electrical energy sources.
Repairs were made to aircraft A and aircraft B to replace unserviceable
components with new or serviceable components. After carrying out the
troubleshooting process in the form of data collection and after that performing a
visual check, the results of these components can be seen. This activity uses
directions from AMM Boeing 737-300 aircraft chapter 49.
When you have replaced the components, you can do a final test to ensure that
the APU is back to normal. The results obtained from the final test, namely the APU
from the two related aircraft, obtained information, namely the APU was normal with
an indication of a normal oil temperature of 130 oC and an engine speed that was
able to reach 100% according to the starting time of 90 seconds. The result of this
troubleshooting is that both aircraft are back to normal or serviceable.