Narrative:

Upon inspection of the maintenance log book prior to flight, I noticed some discrepancies concerning MEL 21-51-01B (air conditioning packs) and 21-24-02 (display unit supply fans). I called maintenance control to inquire why these write ups appeared to be cleared on one page, but not the other pages. A mechanic was sent out to our aircraft. After speaking with maintenance control, he discovered that the left pack was still deferred but that the display unit fan had indeed been cleared in ZZZ2, but had not been reported to air carrier maintenance control. He removed the placard from the avionics cooling fan selector panel and informed us the MEL was cleared. The mechanic, however, had failed to remove the collar from the appropriate circuit breakers and we received the display cool caution message again while at the gate. I again called maintenance control and the same mechanic arrived and decided to defer the display fan and to collar circuit breaker on C6 and C9 in accordance with MEL (21-24-02). Notwithstanding all of this, we departed gate on time and took off for ZZZ1. While climbing through FL230, the first officer noticed a 'display temperature' warning message on his mfd. Shortly thereafter, I noticed the same message on my mfd and then this was followed by a loss of the flight attitude display on both pfd's. We also had a display cool caution message. After running the relevant QRH, I asked for vectors back to ZZZ, and declared an emergency. An appropriate passenger announcement was made and the flight attendant was kept informed of things. We continued to ZZZ where we landed. Upon landing, the aircraft was met by crash fire rescue equipment and maintenance personnel as well as customer service agents. While stowing the reverse thrust, we also received a right rev unlocked caution message. We decided to deplane the passenger while maintenance worked on the ship. Callback conversation with reporter revealed the following information: the reporter stated the technician returned twice to the airplane to bring order to the logbook. The reporter said the technician decided to again defer the primary display cooling fan and pulled and collared the circuit breaker. The reporter stated while climbing through fl 230 the first officer noticed the 'display temperature' warning on the multi-functional display unit. The reporter said the same warning appeared on the captain's multi-functional display unit followed by a loss of the primary flight displays on both sides. The reporter stated a display 'cool caution' message was illuminated. The reporter said an emergency was declared and diversion started. The reporter stated the standby instruments operated ok and on the ground it was found the primary display cooling fan and the altitude display cooling fan was inoperative due to circuit breakers found pulled and collared. The reporter said the breakers were reset and both fans operated normally.

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Original NASA ASRS Text

Title: A CANADAIR CL-65 WAS DISPATCHED IN NON COMPLIANCE WITH BOTH THE PRIMARY AND ALTERNATE DISPLAY UNIT COOLING FANS INOPERATIVE.

Narrative: UPON INSPECTION OF THE MAINT LOG BOOK PRIOR TO FLT, I NOTICED SOME DISCREPANCIES CONCERNING MEL 21-51-01B (AIR CONDITIONING PACKS) AND 21-24-02 (DISPLAY UNIT SUPPLY FANS). I CALLED MAINT CTL TO INQUIRE WHY THESE WRITE UPS APPEARED TO BE CLEARED ON ONE PAGE, BUT NOT THE OTHER PAGES. A MECHANIC WAS SENT OUT TO OUR ACFT. AFTER SPEAKING WITH MAINT CTL, HE DISCOVERED THAT THE L PACK WAS STILL DEFERRED BUT THAT THE DISPLAY UNIT FAN HAD INDEED BEEN CLEARED IN ZZZ2, BUT HAD NOT BEEN RPTED TO ACR MAINT CTL. HE REMOVED THE PLACARD FROM THE AVIONICS COOLING FAN SELECTOR PANEL AND INFORMED US THE MEL WAS CLEARED. THE MECHANIC, HOWEVER, HAD FAILED TO REMOVE THE COLLAR FROM THE APPROPRIATE CIRCUIT BREAKERS AND WE RECEIVED THE DISPLAY COOL CAUTION MESSAGE AGAIN WHILE AT THE GATE. I AGAIN CALLED MAINT CTL AND THE SAME MECH ARRIVED AND DECIDED TO DEFER THE DISPLAY FAN AND TO COLLAR CB ON C6 AND C9 IN ACCORDANCE WITH MEL (21-24-02). NOTWITHSTANDING ALL OF THIS, WE DEPARTED GATE ON TIME AND TOOK OFF FOR ZZZ1. WHILE CLBING THROUGH FL230, THE FO NOTICED A 'DISPLAY TEMP' WARNING MESSAGE ON HIS MFD. SHORTLY THEREAFTER, I NOTICED THE SAME MESSAGE ON MY MFD AND THEN THIS WAS FOLLOWED BY A LOSS OF THE FLT ATTITUDE DISPLAY ON BOTH PFD'S. WE ALSO HAD A DISPLAY COOL CAUTION MESSAGE. AFTER RUNNING THE RELEVANT QRH, I ASKED FOR VECTORS BACK TO ZZZ, AND DECLARED AN EMER. AN APPROPRIATE PAX ANNOUNCEMENT WAS MADE AND THE FA WAS KEPT INFORMED OF THINGS. WE CONTINUED TO ZZZ WHERE WE LANDED. UPON LNDG, THE ACFT WAS MET BY CFR AND MAINT PERSONNEL AS WELL AS CUSTOMER SERVICE AGENTS. WHILE STOWING THE REVERSE THRUST, WE ALSO RECEIVED A R REV UNLOCKED CAUTION MESSAGE. WE DECIDED TO DEPLANE THE PAX WHILE MAINT WORKED ON THE SHIP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE TECHNICIAN RETURNED TWICE TO THE AIRPLANE TO BRING ORDER TO THE LOGBOOK. THE RPTR SAID THE TECHNICIAN DECIDED TO AGAIN DEFER THE PRIMARY DISPLAY COOLING FAN AND PULLED AND COLLARED THE CIRCUIT BREAKER. THE RPTR STATED WHILE CLBING THROUGH FL 230 THE FO NOTICED THE 'DISPLAY TEMP' WARNING ON THE MULTI-FUNCTIONAL DISPLAY UNIT. THE RPTR SAID THE SAME WARNING APPEARED ON THE CAPT'S MULTI-FUNCTIONAL DISPLAY UNIT FOLLOWED BY A LOSS OF THE PRIMARY FLT DISPLAYS ON BOTH SIDES. THE RPTR STATED A DISPLAY 'COOL CAUTION' MESSAGE WAS ILLUMINATED. THE RPTR SAID AN EMER WAS DECLARED AND DIVERSION STARTED. THE RPTR STATED THE STANDBY INSTS OPERATED OK AND ON THE GND IT WAS FOUND THE PRIMARY DISPLAY COOLING FAN AND THE ALT DISPLAY COOLING FAN WAS INOPERATIVE DUE TO CIRCUIT BREAKERS FOUND PULLED AND COLLARED. THE RPTR SAID THE BREAKERS WERE RESET AND BOTH FANS OPERATED NORMALLY.

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.