Narrative:

In reference to this aircraft came in with #1 ahrs overheat message. Discover that the ahrs #1 fan was installed backwards with the arrow pointing up. Closer inspection of the aircraft maintenance log discovered that I installed the fan. Aircraft came in with first officer's pitch trim switch inoperative. While installing the first officer's pitch trim switch we noticed that EICAS show #1 ahr overheat. I was working with mr X. He went to get the ahc's fan and help me to loosen the #1 fan and disconnected 1 wire (the black wire). He could not disconnect the red wire due to difficulty with an injured left arm. I proceeded to install the #ahc fan; first connecting the black wire to the only place I could connected and then disconnect the red wire from the old fan and connecting the red wire from the new fan. I installed the fan in accordance with 34-21-03. Printed the instructions for the installation. Step I(1) and J(2) in my perception the airflow arrow on the fan was pointing down as well as the airflow. Aircraft flew for 10 days without a #1 ahc overheat discrepancy. The corrective action for the repaired of #1 ahc overheat for aircraft was to put ahrs #1 fan wires in correct order.

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Original NASA ASRS Text

Title: AN EMB145 AWAITING TKOF CLRNC GOT A #1 INST COOLING FAN WARNING. RETURNED TO THE GATE. FOUND COOLING FAN INSTALLED INCORRECTLY.

Narrative: IN REF TO THIS ACFT CAME IN WITH #1 AHRS OVERHEAT MESSAGE. DISCOVER THAT THE AHRS #1 FAN WAS INSTALLED BACKWARDS WITH THE ARROW POINTING UP. CLOSER INSPECTION OF THE ACFT MAINT LOG DISCOVERED THAT I INSTALLED THE FAN. ACFT CAME IN WITH FO'S PITCH TRIM SWITCH INOP. WHILE INSTALLING THE FO'S PITCH TRIM SWITCH WE NOTICED THAT EICAS SHOW #1 AHR OVERHEAT. I WAS WORKING WITH MR X. HE WENT TO GET THE AHC'S FAN AND HELP ME TO LOOSEN THE #1 FAN AND DISCONNECTED 1 WIRE (THE BLACK WIRE). HE COULD NOT DISCONNECT THE RED WIRE DUE TO DIFFICULTY WITH AN INJURED L ARM. I PROCEEDED TO INSTALL THE #AHC FAN; FIRST CONNECTING THE BLACK WIRE TO THE ONLY PLACE I COULD CONNECTED AND THEN DISCONNECT THE RED WIRE FROM THE OLD FAN AND CONNECTING THE RED WIRE FROM THE NEW FAN. I INSTALLED THE FAN IN ACCORDANCE WITH 34-21-03. PRINTED THE INSTRUCTIONS FOR THE INSTALLATION. STEP I(1) AND J(2) IN MY PERCEPTION THE AIRFLOW ARROW ON THE FAN WAS POINTING DOWN AS WELL AS THE AIRFLOW. ACFT FLEW FOR 10 DAYS WITHOUT A #1 AHC OVERHEAT DISCREPANCY. THE CORRECTIVE ACTION FOR THE REPAIRED OF #1 AHC OVERHEAT FOR ACFT WAS TO PUT AHRS #1 FAN WIRES IN CORRECT ORDER.

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.