A SF340's hydraulic pump was stuck in the 'continuous mode' after engine start. The aircraft was shu...

Attributes
ACN	897805
Time
Date	201007
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Saab 340 Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Component
Aircraft Component	Hydraulic Main System - Regulator
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 33 Flight Crew Total 4000 Flight Crew Type 2700
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Commercial
Experience	Flight Crew Last 90 Days 35 Flight Crew Total 2500 Flight Crew Type 2000
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

Narrative:

My first officer and I were getting ready to fly. I performed the turn check and the starting engine check. I started the number two engine and all engine instruments were normal. I went to do my after start flow and the hydraulic pump starting running. I noticed the pump was not shutting off after about 10 seconds. I attempted to turn the hydraulic pump off manually; however; the hydraulic pump continued to run. Even after I shut down the number two engine; the pump continued to run. I turned both batteries off to cycle the power. Once turning both batteries back on; the pump was not running continuously. I called maintenance control and they said if the pump is not running continuously then the aircraft power reset the relay and it is ok to continue. I then started the number two engine followed by the number one engine. I performed the after start flow and checklist. As we were taxiing out to runway the hydraulic pump would cycle on and off; but take a little longer than normal. The first officer and I decided to error on the side of safety and return to the gate to have maintenance make sure it was working correctly. Contract maintenance came to the airplane and signed off the discrepancy right away.

Original NASA ASRS Text

Title: A SF340's hydraulic pump was stuck in the 'Continuous Mode' after engine start. The aircraft was shutdown; power removed; and the pump continued to function oddly so the crew returned to the gate for Contract Maintenance repair. Air Carrier Maintenance originally allowed them to continue with the malfunction but the crew decided not to.

Narrative: My First Officer and I were getting ready to fly. I performed the turn check and the starting engine check. I started the number two engine and all engine instruments were normal. I went to do my after start flow and the hydraulic pump starting running. I noticed the pump was not shutting off after about 10 seconds. I attempted to turn the hydraulic pump off manually; however; the hydraulic pump continued to run. Even after I shut down the number two engine; the pump continued to run. I turned both batteries off to cycle the power. Once turning both batteries back on; the pump was not running continuously. I called Maintenance Control and they said if the pump is not running continuously then the aircraft power reset the relay and it is OK to continue. I then started the number two engine followed by the number one engine. I performed the after start flow and checklist. As we were taxiing out to runway the hydraulic pump would cycle on and off; but take a little longer than normal. The First Officer and I decided to error on the side of safety and return to the gate to have maintenance make sure it was working correctly. Contract Maintenance came to the airplane and signed off the discrepancy right away.

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.