Narrative:

Crew had a normal boarding, push, takeoff and area departure. During climb from the orlando area, icing conditions were anticipated, so wing and engine cowl anti-ice system were selected on after takeoff. During climb, anti-ice system functioned normally. Although no ice was detected by ice detection system, crew was IMC with total air temperature in the ice range. Climbing through 15500 ft, an 'anti-ice duct' aural message and triple chime red message was displayed on the EICAS. A review of the system syn page showed the ducting between the fourteenth stage bleed manifold and wing was red and in an overheat condition. Captain called for the QRH procedure which was accomplished by the first officer, directing the crew to turn off the anti-ice system and isolate the fourteenth stage bleed system. This was done. However, climbing through 17000 ft, the ice detectors displayed an 'ice' aural message and a trip chime red message. With the first officer talking to the company on #2 radio and captain flying the aircraft and talking to ATC, I requested a descent to a lower altitude to clear the icing conditions, also as directed by QRH procedure. Being so early into flight and operating in IMC, crew decided a return for landing in orlando was warranted. Captain requested and received clearance from ZJX a return to mco for precautionary landing. Crew then completed arrival checklists. However with the possibility of more ice on arrival, crew elected to use the 'landing with residual ice' procedure. With a substantial increase in approach and landing speed, captain requested crash fire rescue equipment to stand by for our arrival. Crew completed the rest of the abnormal and normal checklists for arrival. The approach and landing were made by the captain without incident. Crew requested an inspection of aircraft landing gear to ensure no tires had blown on arrival. A good report was received from crash fire rescue equipment, so crew taxied aircraft to mco gate. Callback conversation with reporter revealed the following information: the reporter stated the aircraft was a canadair CL65. The reporter said maintenance discovered the right wing fourteenth stage bleed manifold and wing anti-ice ducting all in good condition. The reporter said maintenance found the overheat warning sensing loop broken and shorted to ground causing the false warning.

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Original NASA ASRS Text

Title: A CANADAIR CL65 IN CLB AT 15500 FT DIVERTED DUE TO R FOURTEENTH STAGE BLEED MANIFOLD AND WING ANTI-ICE DUCT OVERHEAT WARNING CAUSED BY A FAILED SENSING LOOP.

Narrative: CREW HAD A NORMAL BOARDING, PUSH, TKOF AND AREA DEP. DURING CLB FROM THE ORLANDO AREA, ICING CONDITIONS WERE ANTICIPATED, SO WING AND ENG COWL ANTI-ICE SYS WERE SELECTED ON AFTER TKOF. DURING CLIMB, ANTI-ICE SYS FUNCTIONED NORMALLY. ALTHOUGH NO ICE WAS DETECTED BY ICE DETECTION SYS, CREW WAS IMC WITH TOTAL AIR TEMP IN THE ICE RANGE. CLBING THROUGH 15500 FT, AN 'ANTI-ICE DUCT' AURAL MESSAGE AND TRIPLE CHIME RED MESSAGE WAS DISPLAYED ON THE EICAS. A REVIEW OF THE SYS SYN PAGE SHOWED THE DUCTING BETWEEN THE FOURTEENTH STAGE BLEED MANIFOLD AND WING WAS RED AND IN AN OVERHEAT CONDITION. CAPT CALLED FOR THE QRH PROC WHICH WAS ACCOMPLISHED BY THE FO, DIRECTING THE CREW TO TURN OFF THE ANTI-ICE SYS AND ISOLATE THE FOURTEENTH STAGE BLEED SYS. THIS WAS DONE. HOWEVER, CLBING THROUGH 17000 FT, THE ICE DETECTORS DISPLAYED AN 'ICE' AURAL MESSAGE AND A TRIP CHIME RED MESSAGE. WITH THE FO TALKING TO THE COMPANY ON #2 RADIO AND CAPT FLYING THE ACFT AND TALKING TO ATC, I REQUESTED A DSCNT TO A LOWER ALT TO CLR THE ICING CONDITIONS, ALSO AS DIRECTED BY QRH PROC. BEING SO EARLY INTO FLT AND OPERATING IN IMC, CREW DECIDED A RETURN FOR LNDG IN ORLANDO WAS WARRANTED. CAPT REQUESTED AND RECEIVED CLRNC FROM ZJX A RETURN TO MCO FOR PRECAUTIONARY LNDG. CREW THEN COMPLETED ARR CHECKLISTS. HOWEVER WITH THE POSSIBILITY OF MORE ICE ON ARR, CREW ELECTED TO USE THE 'LNDG WITH RESIDUAL ICE' PROC. WITH A SUBSTANTIAL INCREASE IN APCH AND LNDG SPD, CAPT REQUESTED CFR TO STAND BY FOR OUR ARR. CREW COMPLETED THE REST OF THE ABNORMAL AND NORMAL CHECKLISTS FOR ARR. THE APCH AND LNDG WERE MADE BY THE CAPT WITHOUT INCIDENT. CREW REQUESTED AN INSPECTION OF ACFT LNDG GEAR TO ENSURE NO TIRES HAD BLOWN ON ARR. A GOOD RPT WAS RECEIVED FROM CFR, SO CREW TAXIED ACFT TO MCO GATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT WAS A CANADAIR CL65. THE RPTR SAID MAINT DISCOVERED THE R WING FOURTEENTH STAGE BLEED MANIFOLD AND WING ANTI-ICE DUCTING ALL IN GOOD CONDITION. THE RPTR SAID MAINT FOUND THE OVERHEAT WARNING SENSING LOOP BROKEN AND SHORTED TO GND CAUSING THE FALSE WARNING.

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.