Splitzer From United Kingdom, joined Feb 2004, 151 posts, RR: 0 Posted (8 years 10 months 3 weeks ago) and read 13472 times:
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).
Fr8mech From United States of America, joined Sep 2005, 6261 posts, RR: 16
Reply 1, posted (8 years 10 months 2 weeks 6 days 21 hours ago) and read 13441 times:
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.
Tristarsteve From Sweden, joined Nov 2005, 4210 posts, RR: 32
Reply 4, posted (8 years 10 months 2 weeks 6 days 12 hours ago) and read 13323 times:
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 From United States of America, joined Feb 2005, 2265 posts, RR: 15
Reply 5, posted (8 years 10 months 2 weeks 6 days 12 hours ago) and read 13316 times:
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
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