Hi all
I just want to clear up a few things about this incident.
1. The aircraft did return to stand earlier for a totally un related defect.
2. The aircraft did not crash.
3. The aircraft did not have a total hydraulic failure
It just lost all the fluid from the centre system. The centre system powers various systems most noticeably the u/c for retraction and the main gear doors for opening and closing. The gear would have been dropped by the alternate system. This is an electric motor that breaks the geometric up locks on the gear. Gravity then causes the gear to “Barge” the doors out of the way and locks it self down. The main gear doors would not retract.
4. The centre system also powers the flaps and slats. They would have been operated on alternate too. The alternate system is a lot slower in operation than the normal system. So the flaps would have not been lowered to the normal landing position because if they had to do a go around this would have created extra drag when you least wanted it! That is why the landing was faster than normal.
5. The centre system powers the steering. That is why the aircraft did not leave the runway under it’s own steam.
4. The aircraft could not have carried on to Chicago in this state
The centre system powers the hydraulic motor driven generator. This is essential for ETOPS operation.
6. The aircraft did not burst the wheels on landing. Two of the wheels deflated because the wheels and brakes were very hot because of the heavy and fast landing the aircraft did. The wheels are designed to do this to prevent a pressure release; this might hurt the ground crew outside the aircraft.
7. The fire service did not smother the brakes with foam or water or “Media” To do this would cause the hot bits to cool to fast and cause other problems. The standard procedure is just let the u/c cool naturally, if you do get a brake fire there are special extinguishers for that. It’s a dry powder that smothers the fire but does not cool it.
8. The Normal brakes on the 767 are powered by the right hydraulic system, so the brakes would have worked normally
9. The reversers are powered by the left and right systems
10. The APU would have been running to provide two sources of electrical power it they had lost an engine
11. Spoilers 3,4,5,8,9 &10 are powered by the centre system so they would not have operated.
All in this entire “incident” was a minor event although I don’t think the people on board woud say so! Perhaps it only made the news because it was a slow news day? The only thing of note for me is that in thirty years in the business I have never seen the fuse plugs go on an aircraft tyre!
Rgds Cking
P.S. Happyonground, You missed me!!!
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