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Flight crew of an light transport descended below assigned altitude when losing the power of one engine due to low oil pressure. With one of the two engines at flight idle, the crew could not hold altitude and they were delayed in contacting ATC due to frequency congestion. Emergency was not declared!
| Attributes | |
| ACN | 335759 |
| Time | |
| Date | 199605 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : rap |
| State Reference | SD |
| Altitude | msl bound lower : 22300 msl bound upper : 23000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv |
| Operator | common carrier : air carrier |
| Make Model Name | Light Transport, Low Wing, 2 Turboprop Eng |
| Operating Under FAR Part | Part 135 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | other other : other pilot : atp pilot : instrument |
| Experience | flight time last 90 days : 200 flight time total : 5000 flight time type : 200 |
| ASRS Report | 335759 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
At FL230 we noticed our right oil pressure gauge was in the red (55 psi). As per the checklist, we brought the right engine to idle to try and discover the problem. Our single engine ceiling is 17000 ft so we were unable to maintain FL230. I was working the radios and requested 17000 ft from ZDV. After the third call, den replied, 'call ZDV on 128.85.' after switching frequencys I had to wait before I could request lower because the controller was too busy. Once I had the controller's attention, I requested 17000 ft. The controller replied 'say your altitude.' I told her we were descending through 22300 ft because we had an oil pressure problem and were unable to maintain 23000 ft and again requested 17000 ft. She gave us 17000 ft. We then received a clearance for a precautionary landing at rap. Technically we busted our altitude at FL230. However, if the 2 controllers would not have been so busy with other traffic, we could have gotten an amended altitude and avoided the whole problem. The center controllers are covering too much territory and too many frequencys. They are not available if you need to get a hold of them in a hurry.
Original NASA ASRS Text
Title: FLC OF AN LTT DSNDED BELOW ASSIGNED ALT WHEN LOSING THE PWR OF ONE ENG DUE TO LOW OIL PRESSURE. WITH ONE OF THE TWO ENGS AT FLT IDLE, THE CREW COULD NOT HOLD ALT AND THEY WERE DELAYED IN CONTACTING ATC DUE TO FREQ CONGESTION. EMER WAS NOT DECLARED!
Narrative: AT FL230 WE NOTICED OUR R OIL PRESSURE GAUGE WAS IN THE RED (55 PSI). AS PER THE CHKLIST, WE BROUGHT THE R ENG TO IDLE TO TRY AND DISCOVER THE PROB. OUR SINGLE ENG CEILING IS 17000 FT SO WE WERE UNABLE TO MAINTAIN FL230. I WAS WORKING THE RADIOS AND REQUESTED 17000 FT FROM ZDV. AFTER THE THIRD CALL, DEN REPLIED, 'CALL ZDV ON 128.85.' AFTER SWITCHING FREQS I HAD TO WAIT BEFORE I COULD REQUEST LOWER BECAUSE THE CTLR WAS TOO BUSY. ONCE I HAD THE CTLR'S ATTN, I REQUESTED 17000 FT. THE CTLR REPLIED 'SAY YOUR ALT.' I TOLD HER WE WERE DSNDING THROUGH 22300 FT BECAUSE WE HAD AN OIL PRESSURE PROB AND WERE UNABLE TO MAINTAIN 23000 FT AND AGAIN REQUESTED 17000 FT. SHE GAVE US 17000 FT. WE THEN RECEIVED A CLRNC FOR A PRECAUTIONARY LNDG AT RAP. TECHNICALLY WE BUSTED OUR ALT AT FL230. HOWEVER, IF THE 2 CTLRS WOULD NOT HAVE BEEN SO BUSY WITH OTHER TFC, WE COULD HAVE GOTTEN AN AMENDED ALT AND AVOIDED THE WHOLE PROB. THE CTR CTLRS ARE COVERING TOO MUCH TERRITORY AND TOO MANY FREQS. THEY ARE NOT AVAILABLE IF YOU NEED TO GET A HOLD OF THEM IN A HURRY.
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.