B737-300 aircraft stick shakers activated at cruise altitude. All indications normal. C/B's pulled.

Attributes
ACN	754952
Time
Date	200709
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zob.artcc
State Reference	OH
Altitude	msl single value : 36000
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	754952
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 200 flight time total : 16000 flight time type : 450
ASRS Report	754951
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	other
Factors
Maintenance	performance deficiency : repair performance deficiency : testing performance deficiency : fault isolation
Supplementary
Problem Areas	Aircraft Maintenance Human Performance
Primary Problem	Aircraft

Narrative:

Cruising at FL360; pilot's stick shaker activated. Aircraft confign at the time was autoplt and autothrottles engaged with LNAV and VNAV selected. I grabbed the controls and clicked off the autothrottles; scanned the captain's and standby airspeed indicator and compared to mine. All 3 indicated 250 KIAS. Stick shaker was still active. I clicked off the autoplt and hand flew the aircraft. Stick shaker still active. Engine instrument and pressurization were all within normal limits. I continued to fly the aircraft and handled the radios as the captain contacted maintenance control and dispatch. Maintenance control had the captain pull circuit breakers D-8 and D-9 on panel P-18-2. Circuit breakers silenced stick shaker. Continued to ZZZ to an uneventful landing. Supplemental information from acn 754951: I have seen a decline in the quality of our maintenance the last few yrs. Flew this plane last night and hydraulic valve for a system was inoperative. On the overnight they said they fixed it and on pushback a system rose to 600 pounds again just like nothing was fixed and had to call maintenance control again. Callback conversation with reporter revealed the following information: reporter stated he and the captain were both quite surprised when the captain's stick shaker went off first followed by his column shaking. With airspeed and angle of attack indications normal and engine instruments and cabin pressurization ok; they looked to silence the stick shakers. Maintenance control directed captain to pull the two C/B's. Reporter does not know what contributed to the errant input that caused the shaker to activate. Their preflight requires them to do a stall warning test using the two test switches on the aft overhead panel and system tested normal. Reporter also noted the decline in the quality of maintenance over the years. The inbound flight they flew; prior to the stick shaker incident; had a problem with the 'a' hydraulic system not depressurizing during #1 engine start. Maintenance said they had fixed the problem; only to find out the 'a' system still did not depressurize.

Original NASA ASRS Text

Title: B737-300 ACFT STICK SHAKERS ACTIVATED AT CRUISE ALTITUDE. ALL INDICATIONS NORMAL. C/B'S PULLED.

Narrative: CRUISING AT FL360; PLT'S STICK SHAKER ACTIVATED. ACFT CONFIGN AT THE TIME WAS AUTOPLT AND AUTOTHROTTLES ENGAGED WITH LNAV AND VNAV SELECTED. I GRABBED THE CTLS AND CLICKED OFF THE AUTOTHROTTLES; SCANNED THE CAPT'S AND STANDBY AIRSPD INDICATOR AND COMPARED TO MINE. ALL 3 INDICATED 250 KIAS. STICK SHAKER WAS STILL ACTIVE. I CLICKED OFF THE AUTOPLT AND HAND FLEW THE ACFT. STICK SHAKER STILL ACTIVE. ENG INST AND PRESSURIZATION WERE ALL WITHIN NORMAL LIMITS. I CONTINUED TO FLY THE ACFT AND HANDLED THE RADIOS AS THE CAPT CONTACTED MAINT CTL AND DISPATCH. MAINT CTL HAD THE CAPT PULL CIRCUIT BREAKERS D-8 AND D-9 ON PANEL P-18-2. CIRCUIT BREAKERS SILENCED STICK SHAKER. CONTINUED TO ZZZ TO AN UNEVENTFUL LNDG. SUPPLEMENTAL INFO FROM ACN 754951: I HAVE SEEN A DECLINE IN THE QUALITY OF OUR MAINT THE LAST FEW YRS. FLEW THIS PLANE LAST NIGHT AND HYD VALVE FOR A SYS WAS INOP. ON THE OVERNIGHT THEY SAID THEY FIXED IT AND ON PUSHBACK A SYS ROSE TO 600 LBS AGAIN JUST LIKE NOTHING WAS FIXED AND HAD TO CALL MAINT CTL AGAIN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED HE AND THE CAPTAIN WERE BOTH QUITE SURPRISED WHEN THE CAPT'S STICK SHAKER WENT OFF FIRST FOLLOWED BY HIS COLUMN SHAKING. WITH AIRSPEED AND ANGLE OF ATTACK INDICATIONS NORMAL AND ENGINE INSTRUMENTS AND CABIN PRESSURIZATION OK; THEY LOOKED TO SILENCE THE STICK SHAKERS. MAINT CONTROL DIRECTED CAPT TO PULL THE TWO C/B'S. REPORTER DOES NOT KNOW WHAT CONTRIBUTED TO THE ERRANT INPUT THAT CAUSED THE SHAKER TO ACTIVATE. THEIR PREFLIGHT REQUIRES THEM TO DO A STALL WARNING TEST USING THE TWO TEST SWITCHES ON THE AFT OVERHEAD PANEL AND SYSTEM TESTED NORMAL. REPORTER ALSO NOTED THE DECLINE IN THE QUALITY OF MAINT OVER THE YEARS. THE INBOUND FLIGHT THEY FLEW; PRIOR TO THE STICK SHAKER INCIDENT; HAD A PROBLEM WITH THE 'A' HYD SYSTEM NOT DEPRESSURIZING DURING #1 ENGINE START. MAINT SAID THEY HAD FIXED THE PROBLEM; ONLY TO FIND OUT THE 'A' SYSTEM STILL DID NOT DEPRESSURIZE.

Data retrieved from NASA's ASRS site as of January 2009 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.