APUs
APUs
Study online at https://quizlet.com/_iu9i4r
1. What is the function of an APU on To supply ground electrical and pneumatic power to
modern transport category aircraft? aircraft systems when the engines are not operating,
and in some aircraft as a backup source of inflight
electrical power.
2. Of what does a typical APU consist? A small turbine powerplant with provisions for supply-
ing bleed air, and an electrical generator that is usually
identical to those mounted on the aircrafts engines.
3. What usually places the greatest de- Bleed air loads.
mand on a gas turbine APU?
4. What is typically used to start an Its own electric starter and battery power.
APU?
5. What is the usual source of a gas One of the aircrafts main fuel tanks.
turbine APUs fuel supply?
6. At what speed does a gas turbine An APU operates at or near its rated speed regardless
APU operate? of the electrical or pneumatic loads imposed.
7. How is a heavily loaded APU, ap- By the use of a load control valve that modulates the
proaching its maximum exhaust gas pneumatic load to maintain a safe operating temper-
temperature (EGT), prevented from ature.
overheating?
8. How is the cool-down for many By running the APU for a specified minimum period of
APUs accomplished prior to shut- time after closing the bleed air valve (unloaded).
down?
9. What is the operating effect of fol- The APUs EGT is lowered and stabilized.
lowing a required cool-down period
prior to APU shutdown?
1/2
APUs
Study online at https://quizlet.com/_iu9i4r
1. What is the function of an APU on To supply ground electrical and pneumatic power to
modern transport category aircraft? aircraft systems when the engines are not operating,
and in some aircraft as a backup source of inflight
electrical power.
2. Of what does a typical APU consist? A small turbine powerplant with provisions for supply-
ing bleed air, and an electrical generator that is usually
identical to those mounted on the aircrafts engines.
3. What usually places the greatest de- Bleed air loads.
mand on a gas turbine APU?
4. What is typically used to start an Its own electric starter and battery power.
APU?
5. What is the usual source of a gas One of the aircrafts main fuel tanks.
turbine APUs fuel supply?
6. At what speed does a gas turbine An APU operates at or near its rated speed regardless
APU operate? of the electrical or pneumatic loads imposed.
7. How is a heavily loaded APU, ap- By the use of a load control valve that modulates the
proaching its maximum exhaust gas pneumatic load to maintain a safe operating temper-
temperature (EGT), prevented from ature.
overheating?
8. How is the cool-down for many By running the APU for a specified minimum period of
APUs accomplished prior to shut- time after closing the bleed air valve (unloaded).
down?
9. What is the operating effect of fol- The APUs EGT is lowered and stabilized.
lowing a required cool-down period
prior to APU shutdown?
1/2
