EMB135 flight crew experienced backup trim system failure.

Attributes
ACN	690561
Time
Date	200603
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : czul.airport
State Reference	FO
Altitude	msl single value : 24000
Environment
Flight Conditions	IMC
Light	Dawn
Aircraft 1
Controlling Facilities	tower : czul.tower
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 135 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	climbout : initial
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	690561
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : overrode automation flight crew : overcame equipment problem
Supplementary
Problem Areas	Company Chart Or Publication Aircraft
Primary Problem	Aircraft

Narrative:

Climbing through FL240; encountered pitch trim main failure on EICAS. Accomplished aom procedure; which is not clear. Encountered backup trim failure as a result of actuating backup trim switch. Followed appropriate backup trim failure checklist; but did not receive EICAS warning of such -- trim system sensed switch actuation; but would not move stabilizer. Re-ran entire aom checklist and ended up clearing the fault but still had intermittent backup trim actuation in nose down direction. Contacted ATC to advise of trim failure; but did not declare emergency as the issue cleared itself up. Received EICAS warning that led us through the checklist in the aom determining the failure of the backup system. Reaction: followed through aom checklist a total of 3 times. 1) upon receipt of the master warning message on the EICAS. 2) upon discovery of the backup trim failure. 3) re-read through entire procedure as the checklist is not organized in a comprehensive way. Suggestions: trim failure checklist calls for the deactivation of the main and/or backup trim system; which precludes any form of troubleshooting stipulated later in the checklist.

Original NASA ASRS Text

Title: EMB135 FLT CREW EXPERIENCED BACKUP TRIM SYS FAILURE.

Narrative: CLBING THROUGH FL240; ENCOUNTERED PITCH TRIM MAIN FAILURE ON EICAS. ACCOMPLISHED AOM PROC; WHICH IS NOT CLR. ENCOUNTERED BACKUP TRIM FAILURE AS A RESULT OF ACTUATING BACKUP TRIM SWITCH. FOLLOWED APPROPRIATE BACKUP TRIM FAILURE CHKLIST; BUT DID NOT RECEIVE EICAS WARNING OF SUCH -- TRIM SYS SENSED SWITCH ACTUATION; BUT WOULD NOT MOVE STABILIZER. RE-RAN ENTIRE AOM CHKLIST AND ENDED UP CLRING THE FAULT BUT STILL HAD INTERMITTENT BACKUP TRIM ACTUATION IN NOSE DOWN DIRECTION. CONTACTED ATC TO ADVISE OF TRIM FAILURE; BUT DID NOT DECLARE EMER AS THE ISSUE CLRED ITSELF UP. RECEIVED EICAS WARNING THAT LED US THROUGH THE CHKLIST IN THE AOM DETERMINING THE FAILURE OF THE BACKUP SYS. REACTION: FOLLOWED THROUGH AOM CHKLIST A TOTAL OF 3 TIMES. 1) UPON RECEIPT OF THE MASTER WARNING MESSAGE ON THE EICAS. 2) UPON DISCOVERY OF THE BACKUP TRIM FAILURE. 3) RE-READ THROUGH ENTIRE PROC AS THE CHKLIST IS NOT ORGANIZED IN A COMPREHENSIVE WAY. SUGGESTIONS: TRIM FAILURE CHKLIST CALLS FOR THE DEACTIVATION OF THE MAIN AND/OR BACKUP TRIM SYS; WHICH PRECLUDES ANY FORM OF TROUBLESHOOTING STIPULATED LATER IN THE CHKLIST.

Data retrieved from NASA's ASRS site as of January 2009 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.