Question about GPU's

[l.a.]

Hello, could someone please explain to me how a Ground Power Unit works. I sort of understand how APU's work and asssume GPU's are similar but just have a few questions. 1) Is a GPU basically an APU that's just external? 2)Can GPU's run airconditioning and electrical systems while a jet's engines are not running. 3) Do most smaller business jets, i.e. a beech jet or a citation II/or 500 have on board apu's are do they require GPU's?

Thanks, I just started flying within the last year and often see small jets hooked up to a power cart and can hear what sounds like an APU running but I am confused why a jet would have an power cart hooked up to it if it already had an APU on board.

 

[A/C FIXER]

Hello, could someone please explain to me how a Ground Power Unit works. I sort of understand how APU's work and asssume GPU's are similar but just have a few questions. 1) Is a GPU basically an APU that's just external? 2)Can GPU's run airconditioning and electrical systems while a jet's engines are not running. 3) Do most smaller business jets, i.e. a beech jet or a citation II/or 500 have on board apu's are do they require GPU's?

Thanks, I just started flying within the last year and often see small jets hooked up to a power cart and can hear what sounds like an APU running but I am confused why a jet would have an power cart hooked up to it if it already had an APU on board.

Let me try to answer your questions.
1. You are correct in assuming that a GPU is similar, with the exception that a GPU does not supply high pressure air to run an aircrafts packs for heating and cooling, the GPU only supplys electrical power.
2. A GPU can be hooked up while a jets engines are running, the pilot just needs to select his ground bus to get power to the aircraft.
3. Most G/A biz jets have their own APUs but not all.
Hope this helps.

 

[l.a.]

Let me try to answer your questions.
1. You are correct in assuming that a GPU is similar, with the exception that a GPU does not supply high pressure air to run an aircrafts packs for heating and cooling, the GPU only supplys electrical power.
2. A GPU can be hooked up while a jets engines are running, the pilot just needs to select his ground bus to get power to the aircraft.
3. Most G/A biz jets have their own APUs but not all.
Hope this helps.

Thanks that helps. So does an APU not run electrical power too? Why would you need a GPU if you already had an APU on the plane?

 

[chufly]

Thanks that helps. So does an APU not run electrical power too? Why would you need a GPU if you already had an APU on the plane?

bottom line. A GPU has a lower fuel burn than an APU. As far as air, a separate cart would be reqiured for A/C and starting of the engines. So... with the fuel prices the way it is, GPU's and air carts are the way to go to save on the cost of fuel.

 

[A/C FIXER]

Thanks that helps. So does an APU not run electrical power too? Why would you need a GPU if you already had an APU on the plane?

Chufly is correct, as the cost of fuel escalates the need to run an APU decreases, at AA we now plug in the GPU as soon as the plane comes to the gate. We have also started taxiing on 1 engine to conserve fuel, and hardly run the APUs at all anymore.

 

[l.a.]

bottom line. A GPU has a lower fuel burn than an APU. As far as air, a separate cart would be reqiured for A/C and starting of the engines. So... with the fuel prices the way it is, GPU's and air carts are the way to go to save on the cost of fuel.

Chufly is correct, as the cost of fuel escalates the need to run an APU decreases, at AA we now plug in the GPU as soon as the plane comes to the gate. We have also started taxiing on 1 engine to conserve fuel, and hardly run the APUs at all anymore.

Thanks guys, I appreciate the info