767 in WAW

[Topper80]

BBC News - Footage shows Boeing 767 emergency landing in Warsaw

Hi all,
how can happen an all gear-up landing in a 767 ? What could be a problem affecting both the normal and alternate gear extension systems?

It's still a commont practice to foam the runway for a no gear landing?

Bye

[old,not bold]

"Foaming a runway" may once have been done, I wouldn't know. It might even have achieved a purpose with aircraft full of gasoline, again, I wouldn't know. And I once ran an airport.

Nowadays it would be a good way to;

(a) reduce the AFS immediate capability to nearly zero (I suspect) shortly before a landing that is more likely to culminate in an emergency involving fire than most,

(b) close the runway for a long time while being cleaned

(c) create a huge environmental hazard with the foam constituents run-off, which could overwhelm the traps

(d) make it very difficult for emergency vehicles to approach a casualty

(e) flush large quantities of money down the toilet

while having no effect at all on the outcome of the event apart from the above.

I've always suspected that it's another media myth, but I'm sure someone can tell us the facts.

[rudderrudderrat]

Hi Topper80,

It's very unusual for two systems to fail - both normal gear lowering and the standby system.

Something vaguely similar happened to a 757 many years ago at LHR. The gear wouldn't come down normally, but the back up free fall system worked OK initially. During the approach the gear retracted so the crew went around and into the hold.

A conversation with Boeing in Seattle requested the total depressurisation of the hydraulic system which the gear was on. The free fall gear system worked and the gear remained down and locked for a successful landing.

There was a fault on the selector valve which caused the hydraulics to raise the gear even when selected down.

[twochai]

This is a strange one: LOT reports a 'central hydraulic system' failure, yet the post-touchdown photographs clearly show the flaps deployed, spoilers deployed and flight controls functioning with elevator surfaces deflected at nearly full 'nose up' position??

[Spanner Turner]

This is a strange one: LOT reports a 'central hydraulic system' failure, yet the post-touchdown photographs clearly show the flaps deployed, spoilers deployed and flight controls functioning with elevator surfaces deflected at nearly full 'nose up' position??

NO NO NO. This is NOT strange in the slightest.

-Flaps and slats have alternate electric function.

-ONLY the spoilers operated by the LEFT and RIGHT hydraulic system are deployed. The spoilers powered by the Centre hydraulic system remain stowed.

-Elevators function just fine from either left, centre or right hydraulic system alone. (Just to be clear - you can lose 2 of the 3 hydraulic systems and elevators and rudder operate 100% normal - there is TRIPLE hydraulic system redundancy for these control surfaces.) (DUAL redundancy for ailerons)

If it happens that you have absolutely no idea about the technical details of a particular aircraft - this is the time you pose a simple question such as

"Is it possible that the flaps/slats can extend, SOME spoilers may deploy and other control surfaces remain operative with a centre hydraulic system failure on a 767 ?"

Answer YES

[Topper80]

So, if LOT had lost the C system (so it become depressurized....), what could be the reason for the failure of the standby gear extension? it's just an uplocjk release, doesn't it? neither any gear doors looks to be open.....

[Swedish Steve]

what could be the reason for the failure of the standby gear extension? it's just an uplocjk release, doesn't it? neither any gear doors looks to be open.....

With C system failure, the alt gear lowering on the B767 consists of a single switch which runs a single electric actuator which turns a quadrant that opens all the gear doors. So a single failure in any of these components would result in alt gear failure.

[threemiles]

ETOPS

Is it common to fly across the Atlantic, certainly ETOPS, with one Hydraulic system inop?

I understand that the MEL is only important for pre-departure, but what happens to items like these en-route?

[AKAAB]

Any chance they had a problem with their RAT heater in EWR and had a similar situation to Spanair?

[NSEU]

Any chance they had a problem with their RAT heater in EWR and had a similar situation to Spanair?

Why would the RAT heating system affect undercarriage deployment?

Are you suggesting it was the source of the hydraulic leak? If so, why would this affect the Gear Alternate (Electric) Extension system?

[Topper80]

I found the big discussion :

http://www.pprune.org/rumours-news/4...p-landing.html