cancidas
Posts: 3985
Joined: Thu Jul 03, 2003 7:34 am

Squares On Bottom Of 757/767

Tue Aug 05, 2003 5:37 am

what's the deal with the squares painted on the bottom of 757 and 767 a/c, like on the song 757 below. i've seen them many times when sitting at the approach ends of rwys. what do they mean?


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Photo © Corey Robinson

"...cannot the kingdom of salvation take me home."
 
mech24
Posts: 47
Joined: Wed Jul 11, 2001 1:15 am

RE: Squares On Bottom Of 757/767

Tue Aug 05, 2003 5:51 am

That is the location of the RAT(Ram Air Turbine). Used for back up hydraulics. Will be deployed automatically by low engine RPM on both engines.
 
HAL
Posts: 1740
Joined: Tue Jan 15, 2002 1:38 am

RE: Squares On Bottom Of 757/767

Tue Aug 05, 2003 5:25 pm

To add to what Mech24 said, the red outline is the door to the RAT. It deploys if both engines quit in flight to provide hydraulic power through the center hydraulic system to the flight controls. It also can be deployed manually by a button on the upper panel in the flight deck. The red outline is to keep people underneath the plane away from below the door. The danger comes from that button in the cockpit. The RAT is spring loaded to open RIGHT NOW when the button is pushed (or if needed when both engines go out). It is a very powerful spring, and as part of our training we are told to ALWAYS stay away from underneath that door. If it opens and hits you, you're probably dead. That's why we sometimes refer to that button as the 'Ramper Snuffer'. It's in poor taste, but accurate.

HAL
One smooth landing is skill. Two in a row is luck. Three in a row and someone is lying.
 
cancidas
Posts: 3985
Joined: Thu Jul 03, 2003 7:34 am

RE: Squares On Bottom Of 757/767

Tue Aug 05, 2003 9:41 pm

cool, thanks .
"...cannot the kingdom of salvation take me home."
 
747Teach
Posts: 176
Joined: Wed Nov 29, 2000 3:05 am

RE: Squares On Bottom Of 757/767

Wed Aug 06, 2003 3:59 am

Cancidas: As the others pointed out, the square outline on the bottom of the fairings is the RAT door. On the 757, the arm that supports the RAT is extended by a spring actuator, and retracted by hydraulic pressure. It can extend very quickly (757 AMM 29-21-00). The RAT on the 767 is extended and retracted by the extend/retract electric motor on the top of the pivot arm, and actually drives out relatively slowly (767 AMM 29-00-05). Regards,
 
cancidas
Posts: 3985
Joined: Thu Jul 03, 2003 7:34 am

RE: Squares On Bottom Of 757/767

Wed Aug 06, 2003 4:37 am

whats the AMM 29-21-00?
"...cannot the kingdom of salvation take me home."
 
atlamt
Posts: 244
Joined: Thu Sep 13, 2001 12:15 am

RE: Squares On Bottom Of 757/767

Wed Aug 06, 2003 6:11 am

It's stands for Aircraft Maintenance Manual the chapter and sub-chapters. Chapter 29 is Hydraulic Power.
Fwd to MCO and Placard
 
Okie
Posts: 3531
Joined: Wed Jul 16, 2003 11:30 am

RE: Squares On Bottom Of 757/767

Wed Aug 06, 2003 9:09 am

So how many times has anyone seen a RAT deployed in flight?
 
covert
Posts: 1498
Joined: Sun Oct 21, 2001 1:02 am

RE: Squares On Bottom Of 757/767

Wed Aug 06, 2003 12:59 pm

Okie,

There are quite a few pictures of the RAT deployed in the database.
none
 
dc10hound
Posts: 460
Joined: Fri Dec 15, 2000 4:18 pm

RE: Squares On Bottom Of 757/767

Wed Aug 06, 2003 8:28 pm

So how many times has anyone seen a RAT deployed in flight?

At AAL, on all Functional Check Flights after heavy maintenance (MBV or C Check), to check correct operation.

"Eagles soar. But weasels never get sucked into jet intakes.."
 
AussiePete
Posts: 70
Joined: Tue May 27, 2003 10:35 am

RE: Squares On Bottom Of 757/767

Fri Aug 08, 2003 2:08 pm

I flew an approach into YSSY on the 767 sim with only the RAT deployed and both engines shutdown. Lets' just say that it's a dire time indeed when it happens for real. Not very responsive flying but it does the job.

I imagine that the Air Canada flight that ran out of fuel and landed on a racetrack a few years ago had the RAT deployed.
 
Rick767
Posts: 2613
Joined: Sun Jan 30, 2000 8:11 pm

RE: Squares On Bottom Of 757/767

Fri Aug 08, 2003 10:02 pm

Here's the said device in all her glory:


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Photo © John Patchett



Wouldn't fancy that slicing my head open on a walkaround...

Viewing this picture in large shows the RAT deployed on a test flight.


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Photo © JOE G. WALKER

I used to love the smell of Jet-A in the morning...

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