Narrative:

We had been operating this aircraft since the morning originator that day. We elected to do a 90% takeoff due to the fact that we were at gross weight from an intersection (reduced was 88.8%). I noticed at a glance of the gauges on the takeoff roll; number 2 inter turbine temperature (itt) was over 700 degrees but within limits. At 400 ft I called for the bleeds on; and it was at this point that the first officer noticed the itt go above 800 degrees; so he reduced power to within acceptable limits. It was while passing through 4;000 ft that the first officer alerted me to the abnormally high itt on the #2 engine. It was still within limits but reaching 780 degrees with torque (tq) at 87% and prop RPM at 1050. As we continued the climb; it became very obvious we could not achieve charted tq for the altitude and temperature outside. At 6;000 ft; with an outside temp of +10 degrees C; we could only achieve 80% tq with an itt of 785. Prop RPM at 1050. The scheduled climb chart indicated that we should be able to achieve 90% tq at that altitude and outside temp. We elected to return to the departure airport and while doing so; we reduced tq and prop RPM to 900. We landed without incident. The previous three flights before this one we'd never gotten above 6;000 ft; so each leg we elected to reduce prop RPM to 900 out of 1;500 ft for passenger comfort. On all three of these legs; on which I took the trends on the second leg; we did notice the #2 engine itt higher than #1; but it did not seem abnormal. All four starts were very normal (in the 640 degree range) without any problems. Also; the engine start we did for the maintenance runup was around the 650 degree range. It was during this run up where we were now unable to achieve tq before exceeding itt (76% @ 785 degrees). It did not matter whether we had the bleed switch on or off; whether the engine control unit (ecu) was on or off; 76% was all that could be achieved with an itt of 785 degrees. We did notice; though; when #2 engine was at flight idle with the bleed switch on #2; itt was 100 degrees higher than #1 engine. This led maintenance to believe there was a bleed problem; which could be a number of different failures of parts. As I looked back through the logbook; I noticed two points of interest - one being that over a 7-day period of trend monitoring; there was an increase to itt; high pressure section RPM (nh) and fuel flow each day on the #2 engine. You could see that from 7 days ago to when I took the trends; #2 engine had increased about 70 degrees. The other being that there were multiple write ups in the previous days for fluid found dripping on the tires from the #2 wheel well. Now the sign off was no hydraulic leaks found; reservoirs were full. They had even put a hydraulic mule on and run services to look for the leaks. This is where I decided to take a closer look at the whole #2 engine area. While inspecting this area; I noticed a louvered vent toward the rear of the cowling on the outboard side missing 3/4 of the louvers. It also appeared that there was heat scoring on the paint aft of this hole. When maintenance arrived a second time and opened the cowling on this side; they discovered a crack 4-5 inches long and about 1/4 inch wide in the shielding around the engine. They said that was not supposed to be there; I would not be ferrying; and in all likelihood; the engine case itself is probably cracked. Well; I found out later that it was. Good thing we elected to return; look more in depth at the logbook; and do another search of the #2 engine area!

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Original NASA ASRS Text

Title: A DHC8-100's engine casing was found cracked during an inspection after the aircraft returned to land because of abnormal ITT; high pressure section RPM; torque and fuel flow readings taken on a the daily engine trend check.

Narrative: We had been operating this aircraft since the morning originator that day. We elected to do a 90% takeoff due to the fact that we were at gross weight from an intersection (reduced was 88.8%). I noticed at a glance of the gauges on the takeoff roll; number 2 inter turbine temperature (ITT) was over 700 degrees but within limits. At 400 ft I called for the bleeds on; and it was at this point that the First Officer noticed the ITT go above 800 degrees; so he reduced power to within acceptable limits. It was while passing through 4;000 ft that the First Officer alerted me to the abnormally high ITT on the #2 engine. It was still within limits but reaching 780 degrees with torque (TQ) at 87% and Prop RPM at 1050. As we continued the climb; it became very obvious we could not achieve charted TQ for the altitude and temperature outside. At 6;000 ft; with an outside temp of +10 degrees C; we could only achieve 80% TQ with an ITT of 785. Prop RPM at 1050. The scheduled climb chart indicated that we should be able to achieve 90% TQ at that altitude and outside temp. We elected to return to the departure airport and while doing so; we reduced TQ and Prop RPM to 900. We landed without incident. The previous three flights before this one we'd never gotten above 6;000 ft; so each leg we elected to reduce Prop RPM to 900 out of 1;500 ft for passenger comfort. On all three of these legs; on which I took the trends on the second leg; we did notice the #2 engine ITT higher than #1; but it did not seem abnormal. All four starts were very normal (in the 640 degree range) without any problems. Also; the engine start we did for the maintenance runup was around the 650 degree range. It was during this run up where we were now unable to achieve TQ before exceeding ITT (76% @ 785 degrees). It did not matter whether we had the bleed switch on or off; whether the engine control unit (ECU) was on or off; 76% was all that could be achieved with an ITT of 785 degrees. We did notice; though; when #2 engine was at flight idle with the bleed switch on #2; ITT was 100 degrees higher than #1 engine. This led maintenance to believe there was a bleed problem; which could be a number of different failures of parts. As I looked back through the logbook; I noticed two points of interest - one being that over a 7-day period of trend monitoring; there was an increase to ITT; high pressure section RPM (NH) and Fuel Flow each day on the #2 engine. You could see that from 7 days ago to when I took the trends; #2 engine had increased about 70 degrees. The other being that there were multiple write ups in the previous days for fluid found dripping on the tires from the #2 wheel well. Now the sign off was no hydraulic leaks found; reservoirs were full. They had even put a hydraulic mule on and run services to look for the leaks. This is where I decided to take a closer look at the whole #2 engine area. While inspecting this area; I noticed a louvered vent toward the rear of the cowling on the outboard side missing 3/4 of the louvers. It also appeared that there was heat scoring on the paint aft of this hole. When maintenance arrived a second time and opened the cowling on this side; they discovered a crack 4-5 inches long and about 1/4 inch wide in the shielding around the engine. They said that was not supposed to be there; I would not be ferrying; and in all likelihood; the engine case itself is probably cracked. Well; I found out later that it was. Good thing we elected to return; look more in depth at the logbook; and do another search of the #2 engine area!

Data retrieved from NASA's ASRS site as of April 2012 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.