Narrative:

The captain and I noticed the oil pressure gauge on the right # 2 engine showed oil pressure slowly decreasing. It fell into the yellow arc on the gauge, yet all other indications remained normal. The captain asked ZID for a descent from 17000 ft to 15000 ft, and in the descent he pulled the torque on the #2 engine back to about 25 percent. The oil pressure continued to fall to the low limit, illuminating a red warning light. We ran through the checklist in its entirety. Initially we had to shut down the engine, which provides for a way to test a second oil pressure warning system. Since the second system was operational, the checklist required us to restart engine #2 and consider the oil pressure gauge unreliable. The flight then continued on to columbus without incident. No report of a precautionary shutdown in flight was made to ATC per far 121.565 because to do so we would have had to interrupt the flow of the checklist, and when the checklist was completed both engines were operating normally and no abnormal situation existed. Callback conversation with reporter revealed the following information: the reporter can add nothing to the report about the engine shutdown. He has been flying the ATR-72 for only about 6 months. This was the only incident of this type that he has seen. He agrees that this is a strange way to check the oil pressure system at first glance, but the procedure works well. His company is complying with the ad regarding the ATR-72, no use of the autoplt while in icing conditions. In addition, the 'company line' is to leave icing conditions as soon as possible. Supplemental information from acn 278728: (local alert only) no TCASII warning. The checklist calls for shutting down the engine, then putting the condition lever to feather. After 30 seconds you should now get a icas warning that there is no oil pressure. If you do get the icas warning, you can restart the engine.

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Original NASA ASRS Text

Title: ENG SHUTDOWN, THEN RESTART.

Narrative: THE CAPT AND I NOTICED THE OIL PRESSURE GAUGE ON THE R # 2 ENG SHOWED OIL PRESSURE SLOWLY DECREASING. IT FELL INTO THE YELLOW ARC ON THE GAUGE, YET ALL OTHER INDICATIONS REMAINED NORMAL. THE CAPT ASKED ZID FOR A DSCNT FROM 17000 FT TO 15000 FT, AND IN THE DSCNT HE PULLED THE TORQUE ON THE #2 ENG BACK TO ABOUT 25 PERCENT. THE OIL PRESSURE CONTINUED TO FALL TO THE LOW LIMIT, ILLUMINATING A RED WARNING LIGHT. WE RAN THROUGH THE CHKLIST IN ITS ENTIRETY. INITIALLY WE HAD TO SHUT DOWN THE ENG, WHICH PROVIDES FOR A WAY TO TEST A SECOND OIL PRESSURE WARNING SYS. SINCE THE SECOND SYS WAS OPERATIONAL, THE CHKLIST REQUIRED US TO RESTART ENG #2 AND CONSIDER THE OIL PRESSURE GAUGE UNRELIABLE. THE FLT THEN CONTINUED ON TO COLUMBUS WITHOUT INCIDENT. NO RPT OF A PRECAUTIONARY SHUTDOWN IN FLT WAS MADE TO ATC PER FAR 121.565 BECAUSE TO DO SO WE WOULD HAVE HAD TO INTERRUPT THE FLOW OF THE CHKLIST, AND WHEN THE CHKLIST WAS COMPLETED BOTH ENGS WERE OPERATING NORMALLY AND NO ABNORMAL SIT EXISTED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR CAN ADD NOTHING TO THE RPT ABOUT THE ENG SHUTDOWN. HE HAS BEEN FLYING THE ATR-72 FOR ONLY ABOUT 6 MONTHS. THIS WAS THE ONLY INCIDENT OF THIS TYPE THAT HE HAS SEEN. HE AGREES THAT THIS IS A STRANGE WAY TO CHK THE OIL PRESSURE SYS AT FIRST GLANCE, BUT THE PROC WORKS WELL. HIS COMPANY IS COMPLYING WITH THE AD REGARDING THE ATR-72, NO USE OF THE AUTOPLT WHILE IN ICING CONDITIONS. IN ADDITION, THE 'COMPANY LINE' IS TO LEAVE ICING CONDITIONS ASAP. SUPPLEMENTAL INFO FROM ACN 278728: (LCL ALERT ONLY) NO TCASII WARNING. THE CHKLIST CALLS FOR SHUTTING DOWN THE ENG, THEN PUTTING THE CONDITION LEVER TO FEATHER. AFTER 30 SECONDS YOU SHOULD NOW GET A ICAS WARNING THAT THERE IS NO OIL PRESSURE. IF YOU DO GET THE ICAS WARNING, YOU CAN RESTART THE ENG.

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.