A CL65 in climb at FL180 declared an emergency and diverted due to elevator split caution warning wi...

Attributes
ACN	625427
Time
Date	200407
Day	Wed
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 18000
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet 700 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	625427
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : elevator split caution warning other flight crewa other flight crewb
Resolutory Action	flight crew : diverted to another airport flight crew : overcame equipment problem flight crew : declared emergency
Consequence	other other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

The flight proceeded normally until passing through FL180. The first officer engaged the autoplt as he had briefed passing through FL180. The aircraft oscillated slightly about 4 times in the pitch axis after autoplt engagement. Very shortly thereafter, the elevator split caution message posted. I decided to access the flight control synoptics page. Then we received an autoplt navigation display caution message. I noticed on the flight control page that the stabilizer trim was running navigation display and there was a very slight elevator split. The left one was slightly lower than the right. I directed the first officer to disengage the autoplt. The autoplt navigation display caution immediately extinguished and the trim stopped moving. The aircraft was completely controllable for the rest of the flight. This all happened within 30-60 seconds. We consulted the aom for the elevator split and subsequently returned uneventfully to ZZZ. We informed the flight attendants, operations, and dispatch of our situation. We declared an emergency with ZZZ center. We did not have to consult with maintenance center because of the high worload as we were west of ZZZ VOR when we began our return. We complied with the aom procedure for elevator split.

Original NASA ASRS Text

Title: A CL65 IN CLB AT FL180 DECLARED AN EMER AND DIVERTED DUE TO ELEVATOR SPLIT CAUTION WARNING WITH AUTOPLT ENGAGED. NORMAL OP WITH AUTOPLT DISENGAGED.

Narrative: THE FLT PROCEEDED NORMALLY UNTIL PASSING THROUGH FL180. THE FO ENGAGED THE AUTOPLT AS HE HAD BRIEFED PASSING THROUGH FL180. THE ACFT OSCILLATED SLIGHTLY ABOUT 4 TIMES IN THE PITCH AXIS AFTER AUTOPLT ENGAGEMENT. VERY SHORTLY THEREAFTER, THE ELEVATOR SPLIT CAUTION MESSAGE POSTED. I DECIDED TO ACCESS THE FLT CTL SYNOPTICS PAGE. THEN WE RECEIVED AN AUTOPLT NAV DISPLAY CAUTION MESSAGE. I NOTICED ON THE FLT CTL PAGE THAT THE STABILIZER TRIM WAS RUNNING NAV DISPLAY AND THERE WAS A VERY SLIGHT ELEVATOR SPLIT. THE L ONE WAS SLIGHTLY LOWER THAN THE R. I DIRECTED THE FO TO DISENGAGE THE AUTOPLT. THE AUTOPLT NAV DISPLAY CAUTION IMMEDIATELY EXTINGUISHED AND THE TRIM STOPPED MOVING. THE ACFT WAS COMPLETELY CONTROLLABLE FOR THE REST OF THE FLT. THIS ALL HAPPENED WITHIN 30-60 SECONDS. WE CONSULTED THE AOM FOR THE ELEVATOR SPLIT AND SUBSEQUENTLY RETURNED UNEVENTFULLY TO ZZZ. WE INFORMED THE FLT ATTENDANTS, OPS, AND DISPATCH OF OUR SIT. WE DECLARED AN EMER WITH ZZZ CTR. WE DID NOT HAVE TO CONSULT WITH MAINT CTR BECAUSE OF THE HIGH WORLOAD AS WE WERE W OF ZZZ VOR WHEN WE BEGAN OUR RETURN. WE COMPLIED WITH THE AOM PROC FOR ELEVATOR SPLIT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A CL65 in climb at FL180 declared an emergency and diverted due to elevator split caution warning with autoplt engaged. Normal operation with autoplt disengaged.