Hiflyer From United States of America, joined Nov 2004, 2132 posts, RR: 4 Reply 6, posted (6 years 10 months 3 weeks 6 days 23 hours ago) and read 4506 times:
That is the 6 prong female end of the ground power cable that is used to power the aircraft when the apu is not operating. Current widebodies require 2 if they are going to keep galley power going and I believe the 380 will need 3. The yellow hose you see off the Captains side is the ground air conditioning...again wide bodies require 2 and the 380 even more! Carriers prefer using ground equipment to supply aircraft if the turn time allows it as it is cheaper than using the apu factoring in fuel costs as well as overhaul costs on the apu after so many hours of use. Most newer airports take that into account and install the needed units on the jetways using city power rather than the older way of having actual ground equipment cluttering the gate running on gasoline or diesel.
TheJoe From Australia, joined Oct 2006, 61 posts, RR: 4 Reply 12, posted (6 years 10 months 3 weeks 6 days 8 hours ago) and read 3914 times:
Quoting HAWK21M (Reply 8): Ground power unit to supply 115vAC 400Hz to the Aircraft on Ground with APU shutdown.
Exactly. If you have a look at the plug itself, it has four heavy duty prongs that provide the 115V 400Hz three phase power to the aircraft. There are also two smaller prongs that are part of the aircraft's 28V DC system as well. The 28V DC prongs are shorter than the four AC prongs for safety reasons. The relay that activates the ground power will not function unless the 28V DC prongs are fully engaged in the plug. That means that the AC prongs will also have to be fully engaged as well. This stops ground power from being activated from the flight deck with the plug only partially engaged preventing shorts and possible injury or death to ground staff who are connecting the aircraft up! This can make it quite difficult on the 737 if the battery is flat. No 28V DC means no ground power! Time for a battery change before power can be applied.
On the 737, the access panel that houses the ground power socket also has two headset jacks. One is the flight interphone used to speak to the crew on a turnaround or provide a method of communication from the tug to the flight deck during towing operations. The other is the service interphone used in conjunction with the other interphone locations on the aircraft for maintenance purposes. In the access panel, there are also two lights. On our 737's, one white light shines when ground power is NOT in use so we know it is safe to disconnect. The other light is red. On when the brakes are set, off when they're not. Handy for a turnaround so you can visually confirm the brakes have been released before commencing a pushback.