View Full Version : Green HYD system pressurization

23rd Oct 2009, 14:29
hello...just this question i always ask my self...in my company SOP and FCOM it says dont pressurize hyd sys on ground without ground clearance,,i asked alot of captins about it always the say to me there was an accident happended because of this,,,any one knows this accident.?
bstg regrds

23rd Oct 2009, 14:34
Its the same in the procedures I am familiar with, never pressurize the hydraulics without clearance from ground. I suspect this is to protect the ground staff from rupturing lines, moving control surfaces and such.... As with most things there probably has been an incident which mandated a modification or addition to procedures - I have absolutely no clue what might have happened in this case specifically - I'm interested to know what happened as well!

23rd Oct 2009, 15:38

Do not pressurize any hidraulic on ground without getting clearance from maintenance personnel.

If the green is pressurized when they have the landing gear doors open for maintenance they would retract and could kill someone.
I think they have use a bypass valve to secure the system to prevent this, but they could forget... So you better ask before doing it.
If you pressurize the yellow, you will pressurize the green, too, with the PTU in AUTO.
As for the blue... Well, I canīt see any danger.

23rd Oct 2009, 15:44
Good point, a lot of hydraulics powered stuff on any aircraft, and who knows who might be working on it - on classic 737s its even customary to leave hydraulic system A unpressurized for pushback since they might not be equipped with steering bypass pins, might be the same for other legacy birds...