splitzer
Posts: 151
Joined: Mon Feb 16, 2004 6:37 am

MD11 - 'Stabilizer Motion' Warning

Wed Oct 18, 2006 9:53 am

Just a quick question - I was watching a video of an MD11 go-around, and heard what sounded like a verbal warning of 'stablizer motion' or 'function'. Having not heard this kind of message on any previous aircraft, can someone please generally clarify on it (what the message is, why it occurs and what technical aspect of the aircraft seemingly makes it specific to the MD11).

To see the video (sound appears at 12.57min mark): http://video.google.com/videoplay?do...808482&q=aborted++takeoff%27&hl=en

Thanks!

Splitzer
 
fr8mech
Posts: 6672
Joined: Mon Sep 26, 2005 9:00 am

RE: MD11 - 'Stabilizer Motion' Warning

Wed Oct 18, 2006 1:19 pm

Most, if not all, transport rated aircraft have some sort of stabilizer in motion warning. These vary from a simple clacker attached to the trim wheel (B727) to a card-in-the-bicycle-spoke type arrangement (B747 classic) to sophisticated aural warnings such is heard on the MD11.

The reason...to let the crew know that the stabilizer is moving. The warning sounds whether the stab is moved by the crew or the autopilot.


Correction: apparently the B757/B767 do not have a stab in transit warning, only an unscheduled trim warning and a loss of full rate trim warning, excluding the take-off warning system. At least I couldn't find mention if a stab in motion warning in the AMM. Perhaps I shall walk out to one of my flying pressure vessels and have a go at the controls.

[Edited 2006-10-18 06:27:53]
When seconds count...the police are minutes away.
 
onetogo
Posts: 286
Joined: Thu Feb 02, 2006 1:40 pm

RE: MD11 - 'Stabilizer Motion' Warning

Wed Oct 18, 2006 3:23 pm

The ATR blasts a freakin ambulance siren every time the stab is in motion. You can only imagine how irritating it must get!
 
PhilSquares
Posts: 3371
Joined: Sun Mar 28, 2004 6:06 pm

RE: MD11 - 'Stabilizer Motion' Warning

Wed Oct 18, 2006 3:38 pm

Quoting Fr8mech (Reply 1):
Correction: apparently the B757/B767 do not have a stab in transit warning

The 744 is the same way. You will get an EICAS caution if there is an uncommand stab trim movement, but that's it.
Fly fast, live slow
 
Tristarsteve
Posts: 3364
Joined: Tue Nov 22, 2005 11:04 pm

RE: MD11 - 'Stabilizer Motion' Warning

Wed Oct 18, 2006 10:15 pm

The Tristar does not need such a warning.
It has a full flying tailplane. When you move the control column, the whole stabilisor moves up and down. The elevators are geared to the stabilisor and move with it.
 
CosmicCruiser
Posts: 2049
Joined: Tue Feb 22, 2005 3:01 am

RE: MD11 - 'Stabilizer Motion' Warning

Wed Oct 18, 2006 10:33 pm

The "stabilzer motion" warning only sounds after the stab trim has been in motion for x number of seconds. It does not sound immediately upon trim movement. As posted it's to alert the crew that the trim has been moving for a few seconds and if they weren't aware now they are.

HORIZONTAL STABILIZER MOTION
WARNING (19.0.0)
The CAWS will provide an aural warning (tone and
voice) when the horizontal stabilizer deviates one
degree or more for a given length of time. The warning
will be on until the horizontal stabilizer sensor
goes off.
 
splitzer
Posts: 151
Joined: Mon Feb 16, 2004 6:37 am

RE: MD11 - 'Stabilizer Motion' Warning

Thu Oct 19, 2006 6:14 am

Thanks everyone for posting. Just what I wanted to know  Smile

Splitzer
 
nonfirm
Posts: 426
Joined: Mon Sep 12, 2005 3:04 pm

RE: MD11 - 'Stabilizer Motion' Warning

Thu Oct 19, 2006 6:32 am

That is the same warning used in the MD-80.  airplane 
 
WSOY
Posts: 822
Joined: Tue Jun 13, 2006 10:24 pm

RE: MD11 - 'Stabilizer Motion' Warning

Thu Oct 19, 2006 9:39 pm

The video actually includes no aborted takeoff, but a go-around (aborted landing) due to other traffic on the JFK runway -- so the description is wrong.
"Nukkuessa tulee nälkä" (Nipsu)

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