Narrative:

I was the captain and the PF on a flight from maf to dfw. At acceleration altitude where climb power and climb checklists are performed, I made the call to my first officer to set climb power and begin the climb checklist. The first officer complied and began his flow. I noticed the first officer retarding the power levers to set climb power, at that point I noticed he had forgotten to dial down the ctot and turn the ctot switch to the off position prior to retarding the power levers to set climb power as a result the right engine began a series of compressor stalls which required me to shut the right engine down, declare an emergency and return to maf. The flight returned safely and without further incident. In my opinion 2 factors were the main cause of this incident. First this was a reduced rest overnight where the crew received about 5 hours of actual sleep before reporting for duty the morning of the incident. Secondly, myself a relatively new captain was paired with a new hire first officer with only about 50 hours total in this aircraft. Supplemental information from acn 293230: on climb out from midland at acceleration altitude the captain said 'yaw damp on climb power climb checks.' I started the flow by switching the yaw damp on and retarding the power levers. When retarding the pwer levers the torque decreased in a normal manner in association with the power lever movement. No jump or spike was noted on the torque gauge. At 90 percent torque the right engine made a bang-bang-bang noise. At this point the captain noticed the right oil pressure light and associated triple chime. He then said 'maximum power confirm right engine failure and positive automatic coarsen.' as I pushed the power levers up to maximum power the banging continued and the propeller appeared to automatic coarsen. When we did the emergency items (ie) the right power lever to flight idle. The banging went away. We then continued with the memory items and completed the checklist for engine failure and shut down procedure. The captain then notified ATC, flight attendant, and the company. We then proceeded to do a visual approach to runway 10 backed up by the ILS to midland, tx, with no further incident. On post flight discussion the captain and I agreed that the ctot was not in the off position prior to the initial power reduction. I do not think this contributed to the problem: the reason I feel this way is due to the fact that: I did not see the torque drop below 90 percent I also did not notice any surge of the torque gauges to 90 percent nor do I think I went past the 64 degree switch. No mechanical problems were found with the right engine. When the aircraft was test flown everything looked normal. After the test flight the aircraft was put back in service. Callback conversation with reporter revealed the following information: the saab 340 has a ctot. In pilot vernacular a sea tot. Ctot is an acronym for constant torque on takeoff. The power setting for takeoff is established by the ctot when a pilot turns on the switch rather than pilot moving the thrust lever. The thrust lever does nothing when retarded until the thrust lever is pulled far enough back to hit a 64 degree switch unless the ctot is turned off prior to retarding the thrust lever at which time the general elcetric CT7-9B will resopnd normally to thrust lever movements. The compressor stalls do not normally occur when the ctot switch is not turned off as happened in this case. In fact, the compressor stalled to the point the 'automatic coarsen' or in other words 'automatic feather' shut the engine down. So, the captain elected to complete all procedures for the automatic shutdown and return and land. The engine was checked by maintenance and found airworthy and the flight continued without further problems. 2 weeks later the engine behaved with the compessor stalls on the acceleration and all procedures were in accordance with company policy. The compressor stalls occurred as the aircraft accelerated and prior to turning off the ctot or or retarding the thrust lever.

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Original NASA ASRS Text

Title: COMPRESSOR STALLS, A RED LOW OIL PRESSURE LIGHT AND AN ASSOCIATED CHIME PROMPTS FLC TO SHUT DOWN ENG, DECLARE AN EMER AND LAND.

Narrative: I WAS THE CAPT AND THE PF ON A FLT FROM MAF TO DFW. AT ACCELERATION ALT WHERE CLB PWR AND CLB CHKLISTS ARE PERFORMED, I MADE THE CALL TO MY FO TO SET CLB PWR AND BEGIN THE CLB CHKLIST. THE FO COMPLIED AND BEGAN HIS FLOW. I NOTICED THE FO RETARDING THE PWR LEVERS TO SET CLB PWR, AT THAT POINT I NOTICED HE HAD FORGOTTEN TO DIAL DOWN THE CTOT AND TURN THE CTOT SWITCH TO THE OFF POS PRIOR TO RETARDING THE PWR LEVERS TO SET CLB PWR AS A RESULT THE R ENG BEGAN A SERIES OF COMPRESSOR STALLS WHICH REQUIRED ME TO SHUT THE R ENG DOWN, DECLARE AN EMER AND RETURN TO MAF. THE FLT RETURNED SAFELY AND WITHOUT FURTHER INCIDENT. IN MY OPINION 2 FACTORS WERE THE MAIN CAUSE OF THIS INCIDENT. FIRST THIS WAS A REDUCED REST OVERNIGHT WHERE THE CREW RECEIVED ABOUT 5 HRS OF ACTUAL SLEEP BEFORE RPTING FOR DUTY THE MORNING OF THE INCIDENT. SECONDLY, MYSELF A RELATIVELY NEW CAPT WAS PAIRED WITH A NEW HIRE FO WITH ONLY ABOUT 50 HRS TOTAL IN THIS ACFT. SUPPLEMENTAL INFO FROM ACN 293230: ON CLBOUT FROM MIDLAND AT ACCELERATION ALT THE CAPT SAID 'YAW DAMP ON CLB PWR CLB CHKS.' I STARTED THE FLOW BY SWITCHING THE YAW DAMP ON AND RETARDING THE PWR LEVERS. WHEN RETARDING THE PWER LEVERS THE TORQUE DECREASED IN A NORMAL MANNER IN ASSOCIATION WITH THE PWR LEVER MOVEMENT. NO JUMP OR SPIKE WAS NOTED ON THE TORQUE GAUGE. AT 90 PERCENT TORQUE THE R ENG MADE A BANG-BANG-BANG NOISE. AT THIS POINT THE CAPT NOTICED THE R OIL PRESSURE LIGHT AND ASSOCIATED TRIPLE CHIME. HE THEN SAID 'MAX PWR CONFIRM R ENG FAILURE AND POSITIVE AUTO COARSEN.' AS I PUSHED THE PWR LEVERS UP TO MAX PWR THE BANGING CONTINUED AND THE PROP APPEARED TO AUTO COARSEN. WHEN WE DID THE EMER ITEMS (IE) THE R PWR LEVER TO FLT IDLE. THE BANGING WENT AWAY. WE THEN CONTINUED WITH THE MEMORY ITEMS AND COMPLETED THE CHKLIST FOR ENG FAILURE AND SHUT DOWN PROC. THE CAPT THEN NOTIFIED ATC, FLT ATTENDANT, AND THE COMPANY. WE THEN PROCEEDED TO DO A VISUAL APCH TO RWY 10 BACKED UP BY THE ILS TO MIDLAND, TX, WITH NO FURTHER INCIDENT. ON POST FLT DISCUSSION THE CAPT AND I AGREED THAT THE CTOT WAS NOT IN THE OFF POS PRIOR TO THE INITIAL PWR REDUCTION. I DO NOT THINK THIS CONTRIBUTED TO THE PROB: THE REASON I FEEL THIS WAY IS DUE TO THE FACT THAT: I DID NOT SEE THE TORQUE DROP BELOW 90 PERCENT I ALSO DID NOT NOTICE ANY SURGE OF THE TORQUE GAUGES TO 90 PERCENT NOR DO I THINK I WENT PAST THE 64 DEG SWITCH. NO MECHANICAL PROBS WERE FOUND WITH THE R ENG. WHEN THE ACFT WAS TEST FLOWN EVERYTHING LOOKED NORMAL. AFTER THE TEST FLT THE ACFT WAS PUT BACK IN SVC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE SAAB 340 HAS A CTOT. IN PLT VERNACULAR A SEA TOT. CTOT IS AN ACRONYM FOR CONSTANT TORQUE ON TKOF. THE PWR SETTING FOR TKOF IS ESTABLISHED BY THE CTOT WHEN A PLT TURNS ON THE SWITCH RATHER THAN PLT MOVING THE THRUST LEVER. THE THRUST LEVER DOES NOTHING WHEN RETARDED UNTIL THE THRUST LEVER IS PULLED FAR ENOUGH BACK TO HIT A 64 DEG SWITCH UNLESS THE CTOT IS TURNED OFF PRIOR TO RETARDING THE THRUST LEVER AT WHICH TIME THE GENERAL ELCETRIC CT7-9B WILL RESOPND NORMALLY TO THRUST LEVER MOVEMENTS. THE COMPRESSOR STALLS DO NOT NORMALLY OCCUR WHEN THE CTOT SWITCH IS NOT TURNED OFF AS HAPPENED IN THIS CASE. IN FACT, THE COMPRESSOR STALLED TO THE POINT THE 'AUTO COARSEN' OR IN OTHER WORDS 'AUTO FEATHER' SHUT THE ENG DOWN. SO, THE CAPT ELECTED TO COMPLETE ALL PROCS FOR THE AUTO SHUTDOWN AND RETURN AND LAND. THE ENG WAS CHKED BY MAINT AND FOUND AIRWORTHY AND THE FLT CONTINUED WITHOUT FURTHER PROBS. 2 WKS LATER THE ENG BEHAVED WITH THE COMPESSOR STALLS ON THE ACCELERATION AND ALL PROCS WERE IN ACCORDANCE WITH COMPANY POLICY. THE COMPRESSOR STALLS OCCURRED AS THE ACFT ACCELERATED AND PRIOR TO TURNING OFF THE CTOT OR OR RETARDING THE THRUST LEVER.

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.