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Q400 captain inadvertently moved both condition levers below the 850 RPM detent then quickly returning them to the proper position. This causes both pec's to drop off line and the checklist advises landing at the nearest suitable airport. Engine surging is experienced during approach but becomes stable prior to landing.
| Attributes | |
| ACN | 968787 |
| Time | |
| Date | 201109 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | Q400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Climb |
| Component | |
| Aircraft Component | Propeller Control |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy |
Narrative:
On climb out; I inadvertently brought the condition levers back to just below the 850 RPM detent. I immediately placed them back to the 850 RPM detent. Even though it was only momentary; the propellers did surge; and both propeller electronic control's (pec's) dropped off line. We completed the checklist; which called for a landing as soon as practical; and returned to the departure airport. Dispatch and maintenance control were both notified; and I made two PA's for the passengers. The only unexpected event occurred on final. Both propeller RPM's began to slightly surge up and down; which was noticeable in the sound of the propellers; as well as a slight yawing back and forth; during the below the line portion of the landing checklist. This involves the flaps going to 35; the bleeds being switched to min; a power change; and an airspeed change; which caused the propellers to come off the overspeed governor. This lasted for 30-45 seconds; then both propeller RPM's remained stable for the remainder of the flight.
Original NASA ASRS Text
Title: Q400 Captain inadvertently moved both condition levers below the 850 RPM detent then quickly returning them to the proper position. This causes both PEC's to drop off line and the checklist advises landing at the nearest suitable airport. Engine surging is experienced during approach but becomes stable prior to landing.
Narrative: On climb out; I inadvertently brought the condition levers back to just below the 850 RPM detent. I immediately placed them back to the 850 RPM detent. Even though it was only momentary; the propellers did surge; and both Propeller Electronic Control's (PEC's) dropped off line. We completed the checklist; which called for a landing as soon as practical; and returned to the departure airport. Dispatch and Maintenance Control were both notified; and I made two PA's for the passengers. The only unexpected event occurred on final. Both propeller RPM's began to slightly surge up and down; which was noticeable in the sound of the propellers; as well as a slight yawing back and forth; during the below the line portion of the landing checklist. This involves the flaps going to 35; the bleeds being switched to min; a power change; and an airspeed change; which caused the propellers to come off the overspeed governor. This lasted for 30-45 seconds; then both propeller RPM's remained stable for the remainder of the flight.
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.