About B717?

Question

hi,

what is the purpose of this hose at this picture ?

http://www2.2space.net/images/upl_newsImage/1187096695.jpg

does it give pneumatic air for starting the engines ? doesnt it have APU ? or it is only a ground power work ?

thanks...

Answer 1

It is pumping air conditioning into the cabin.

It is normally used in winter to warm up the cabin before passengers arrive in the morning.  But sometimes they are used in the summer to cool it down.

Typically they are used when the APU is not running either because it is deferred for maintenance or because the operator is trying to save fuel.

Answer 2

The wide yellow hose is hooked up to a ground air conditioning unit. For whatever reason, the APU is not being used in this case.

If they needed to start the engines with an inoperative APU, they would plug in a different, narrower coiled hose from a ground air start unit. The receptacle is located somewhere else on this aircraft. Once one engine is started at the gate they will disconnect the start hose. The engine that is now running will supply the electrical power and the bleed air for a cross bleed start of the other engine.  Once both engines are started, the air conditioning packs can be supplied with bleed air and off you go.

Answer 3

maybe it is oil changing

Answer 4

I suspect that  APU is not being utilized.

B717 has Toilet service and engine start points on the left side and air conditioning point on the right side.

I think that it is air conditioning system attached on the ground with APU shutdown for economical purpose when aircraft is waiting at the gate.

Check this page:

http://www.boeing.com/commercial/airport...

Answer 5

That hose is for ground air conditioning.  It saves fuel as the APU doesn't need to be used for AC when you are at the gate.  The air hose for starting is smaller and goes in another opening.  Also, the APU might be broken, which would require ground air for AC and starting, as well as electrical power until one of the main engines is started.

Answer 6

After spending years as a Flightline mechanic, I can verify it is an A/C hose used to run the packs without the APU.

Answer 7

It is coming from a PCA Unit (Pre-Conditioned Air).  It provides either heated or cooled air for the cabin of the aircraft.  It is used on the ground so that the APU does not need to be used to run  the A/C packs, due to the high fuel consumption of the APU.  This is NOT the air source used to start the engines, those hoses are much smaller due to the higher pressure requirements.

Answer 8

Normally, they use bleed-air from the aux power unit (APU) to start the engines.  Once the engines have started they shut the APU down.  The APU is not required for flight.

If the APU is down, then they use the air-start hoses to start the engines.