<< >> NASA ASRS Report 481016, August 2000

A B737-200 rejected takeoff due to no airspeed indication on captain's instrument caused by disconnected pitot static line at air data computer.

Attributes
ACN	481016
Time
Date	200008
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tower : sdl.tower
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
Qualification	technician : fcc technician : airframe technician : powerplant
Experience	maintenance avionics : 20
ASRS Report	481016
Person 2
Affiliation	company : air carrier
Function	maintenance : technician
Qualification	technician : fcc technician : powerplant technician : airframe
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance non adherence : company policies non adherence : far non adherence : published procedure other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : rejected takeoff
Consequence	other
Factors
Maintenance	contributing factor : work cards contributing factor : schedule pressure performance deficiency : inspection performance deficiency : testing
Supplementary
Problem Areas	Maintenance Human Performance Aircraft
Primary Problem	Maintenance Human Performance

Narrative:

The autothrottles were inoperative because of a missing signal from the #2 throttle position sensor. I located an open wire behind the E1-2 shelf in the electronics bay. The shelf had to come out to locate the open wire. In order to remove the shelf the pitot static lines had to be disconnected on the #1 and #2 air data computers on the E1-1 shelf. The repair was made and the E1-2 shelf reinstalled and the static lines connected to the #1 and #2 air data computers. An operational check was performed on the autothrottles system and a functional check was performed on the yaw damper system and a hand verify bite was performed on the a and B autoplt system. Side a of the autoplt was previously placed on MEL and was tagged. On takeoff the captain noticed he had no airspeed indication and aborted takeoff. Back at the gate it was discovered that the pitot static connection to the #1 air data computer was dislodged.

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Original NASA ASRS Text

Title: A B737-200 REJECTED TKOF DUE TO NO AIRSPD INDICATION ON CAPT'S INST CAUSED BY DISCONNECTED PITOT STATIC LINE AT AIR DATA COMPUTER.

Narrative: THE AUTOTHROTTLES WERE INOP BECAUSE OF A MISSING SIGNAL FROM THE #2 THROTTLE POS SENSOR. I LOCATED AN OPEN WIRE BEHIND THE E1-2 SHELF IN THE ELECTRONICS BAY. THE SHELF HAD TO COME OUT TO LOCATE THE OPEN WIRE. IN ORDER TO REMOVE THE SHELF THE PITOT STATIC LINES HAD TO BE DISCONNECTED ON THE #1 AND #2 AIR DATA COMPUTERS ON THE E1-1 SHELF. THE REPAIR WAS MADE AND THE E1-2 SHELF REINSTALLED AND THE STATIC LINES CONNECTED TO THE #1 AND #2 AIR DATA COMPUTERS. AN OPERATIONAL CHK WAS PERFORMED ON THE AUTOTHROTTLES SYS AND A FUNCTIONAL CHK WAS PERFORMED ON THE YAW DAMPER SYS AND A HAND VERIFY BITE WAS PERFORMED ON THE A AND B AUTOPLT SYS. SIDE A OF THE AUTOPLT WAS PREVIOUSLY PLACED ON MEL AND WAS TAGGED. ON TKOF THE CAPT NOTICED HE HAD NO AIRSPD INDICATION AND ABORTED TKOF. BACK AT THE GATE IT WAS DISCOVERED THAT THE PITOT STATIC CONNECTION TO THE #1 AIR DATA COMPUTER WAS DISLODGED.

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.