B737-700 first officer reported failure of engine driven hydraulic system a. They declared an emerge...

Narrative:

Engine driven system 'a' hydraulic failure. (System 'a' engine driven hydraulic low pressure light on; hydraulic light on system annunciator panel; and master caution light.) ran checklist for event. Also; thoroughly reviewed and discussed total system 'a' failure just in case. While at cruise at FL370; we got the above indications; which were preceded by rapid drop in system 'a' quantity to about 18%. Ran checklist; talked to dispatch; and requested that ATC notify [divert destination] to have emergency crews standing by just in case the malfunction evolved into a full system 'a' failure.initially dispatch told us to proceed to [diversion airport option 1] then about 15 minutes later dispatch instructed us to divert to [diversion airport option 2]. We discussed other possibilities should the emergency continue to get worse - it didn't. Got vectors; configured a little early and normally; which was uneventful. Landing was uneventful. Taxied back to gate but captain noticed that when finer steering inputs were required that the aircraft was sluggish. Decided to stop aircraft and be towed to the gate. The system 'a' hydraulic system had three previous writeups of hydraulics needing service and aircraft notations that hydraulic quantity dropping quickly. Maintenance did do an engine run and had us cycle flight controls. No leak detected. Not sure what more could have been done.

Original NASA ASRS Text

Title: B737-700 First Officer reported failure of Engine Driven Hydraulic System A. They declared an emergency and diverted to a suitable nearby airport for a safe landing.

Narrative: Engine Driven System 'A' Hydraulic failure. (System 'A' Engine Driven Hydraulic Low Pressure light on; hydraulic light on system annunciator panel; and master caution light.) Ran checklist for event. Also; thoroughly reviewed and discussed total System 'A' failure just in case. While at cruise at FL370; we got the above indications; which were preceded by rapid drop in System 'A' quantity to about 18%. Ran checklist; talked to Dispatch; and requested that ATC notify [divert destination] to have emergency crews standing by just in case the malfunction evolved into a full System 'A' failure.Initially Dispatch told us to proceed to [diversion airport option 1] then about 15 minutes later Dispatch instructed us to divert to [diversion airport option 2]. We discussed other possibilities should the emergency continue to get worse - it didn't. Got vectors; configured a little early and normally; which was uneventful. Landing was uneventful. Taxied back to gate but Captain noticed that when finer steering inputs were required that the aircraft was sluggish. Decided to stop aircraft and be towed to the gate. The System 'A' hydraulic system had three previous writeups of hydraulics needing service and aircraft notations that hydraulic quantity dropping quickly. Maintenance did do an engine run and had us cycle flight controls. No leak detected. Not sure what more could have been done.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1025444
Time
Date	201207
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Hydraulic Main System
Person 1
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 196 Flight Crew Type 6000
Events
Anomaly	Aircraft Equipment Problem Critical

B737-700 first officer reported failure of engine driven hydraulic system a. They declared an emergency and diverted to a suitable nearby airport for a safe landing.