B737-300 crew discovered 'a' flight control hydraulic pressure warning light illuminated. Pressure o...

Attributes
ACN	627574
Time
Date	200408
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 3000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : zzz.tracon tower : las.tower
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	627574
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	627576
Events
Anomaly	aircraft equipment problem : critical maintenance problem : non compliance with mel non adherence : far non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : a low pressure warning light other flight crewa other flight crewb
Resolutory Action	flight crew : overcame equipment problem other
Consequence	other other
Factors
Maintenance	contributing factor : manuals performance deficiency : testing
Supplementary
Problem Areas	Aircraft Chart Or Publication Flight Crew Human Performance Maintenance Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Flight taxied out on 1 engine (#2). First officer started #1 engine while on taxiway east. While performing the after start flow, first officer noticed low pressure light (a flight control) was illuminated. Captain called for taxi check. The flow and checklist were completed, noting that the flight control light remained illuminated after recall, then it was canceled. Taxied to cargo ramp, captain set brakes. Captain positioned 'a' flight control switch to standby rudder (standby rudder checked good), checked hydraulic quantity and pressures (both normal). Read through the ambiguous and misleading MEL 27-5 condition 1 and concluded it was a false indication. Called maintenance control to verify compliance and got the ok to go by both maintenance and dispatch. Captain was the PF. After takeoff at 3000 ft, after flap retraction, the aircraft rolled to one side then the other (between 20-30 degrees each direction). Very similar to wake turbulence from a heavy aircraft, but there was no heavy jet in front of us. Captain stated that the flight controls did not feel right. First officer and captain looked up and noticed that not only was the low pressure light illuminated but the feel differential light was on as well. At this time, captain made the decision to return to ZZZ. First officer notified ATC that a return to ZZZ was necessary for a precautionary landing. The approach and landing was uneventful. Weight and rate of descent was noted for the overweight landing.

Original NASA ASRS Text

Title: B737-300 CREW DISCOVERED 'A' FLT CTL HYD PRESSURE WARNING LIGHT ILLUMINATED. PRESSURE OK. DEFERRED PER MEL. INFLT, GOT FEEL DIFFERENTIAL LOW PRESSURE WARNING LIGHT. CREW ELECTED TO DIVERT.

Narrative: FLT TAXIED OUT ON 1 ENG (#2). FO STARTED #1 ENG WHILE ON TXWY E. WHILE PERFORMING THE AFTER START FLOW, FO NOTICED LOW PRESSURE LIGHT (A FLT CTL) WAS ILLUMINATED. CAPT CALLED FOR TAXI CHK. THE FLOW AND CHKLIST WERE COMPLETED, NOTING THAT THE FLT CTL LIGHT REMAINED ILLUMINATED AFTER RECALL, THEN IT WAS CANCELED. TAXIED TO CARGO RAMP, CAPT SET BRAKES. CAPT POSITIONED 'A' FLT CTL SWITCH TO STANDBY RUDDER (STANDBY RUDDER CHKED GOOD), CHKED HYD QUANTITY AND PRESSURES (BOTH NORMAL). READ THROUGH THE AMBIGUOUS AND MISLEADING MEL 27-5 CONDITION 1 AND CONCLUDED IT WAS A FALSE INDICATION. CALLED MAINT CTL TO VERIFY COMPLIANCE AND GOT THE OK TO GO BY BOTH MAINT AND DISPATCH. CAPT WAS THE PF. AFTER TKOF AT 3000 FT, AFTER FLAP RETRACTION, THE ACFT ROLLED TO ONE SIDE THEN THE OTHER (BTWN 20-30 DEGS EACH DIRECTION). VERY SIMILAR TO WAKE TURB FROM A HVY ACFT, BUT THERE WAS NO HVY JET IN FRONT OF US. CAPT STATED THAT THE FLT CTLS DID NOT FEEL RIGHT. FO AND CAPT LOOKED UP AND NOTICED THAT NOT ONLY WAS THE LOW PRESSURE LIGHT ILLUMINATED BUT THE FEEL DIFFERENTIAL LIGHT WAS ON AS WELL. AT THIS TIME, CAPT MADE THE DECISION TO RETURN TO ZZZ. FO NOTIFIED ATC THAT A RETURN TO ZZZ WAS NECESSARY FOR A PRECAUTIONARY LNDG. THE APCH AND LNDG WAS UNEVENTFUL. WT AND RATE OF DSCNT WAS NOTED FOR THE OVERWT LNDG.

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.

B737-300 crew discovered 'a' flight control hydraulic pressure warning light illuminated. Pressure ok. Deferred per MEL. In-flight, got feel differential low pressure warning light. Crew elected to divert.