An MD80 rudder power unit incorrectly adjusted during replacement.

Attributes
ACN	348529
Time
Date	199609
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : fay
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	348529
Person 2
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

I and 2 other aircraft a&P mechanics finished up the aircraft turnover of an installation of the rudder hydraulic power package per job card and reference maintenance manual. During the installation we misunderstood the job card step on nulling the yaw damper and did not accomplish this step correctly. Therefore we did not adjust the rudder throw limiter proximity sensors to their proper gap dimensions which caused the 'rudder travel unrestr' light on the overhead central warning panel to go out too early in the flight. Indication problem only -- no one was in danger at all. This was the first time that I or the other 2 mechanics replaced a rudder hydraulic power package. If one of us had changed one before we could have prevented this 'return to field' occurrence by catching our mistake at final installation of the rudder throw limiter proximity switches.

Original NASA ASRS Text

Title: AN MD80 RUDDER PWR UNIT INCORRECTLY ADJUSTED DURING REPLACEMENT.

Narrative: I AND 2 OTHER ACFT A&P MECHS FINISHED UP THE ACFT TURNOVER OF AN INSTALLATION OF THE RUDDER HYD PWR PACKAGE PER JOB CARD AND REF MAINT MANUAL. DURING THE INSTALLATION WE MISUNDERSTOOD THE JOB CARD STEP ON NULLING THE YAW DAMPER AND DID NOT ACCOMPLISH THIS STEP CORRECTLY. THEREFORE WE DID NOT ADJUST THE RUDDER THROW LIMITER PROX SENSORS TO THEIR PROPER GAP DIMENSIONS WHICH CAUSED THE 'RUDDER TRAVEL UNRESTR' LIGHT ON THE OVERHEAD CENTRAL WARNING PANEL TO GO OUT TOO EARLY IN THE FLT. INDICATION PROB ONLY -- NO ONE WAS IN DANGER AT ALL. THIS WAS THE FIRST TIME THAT I OR THE OTHER 2 MECHS REPLACED A RUDDER HYD PWR PACKAGE. IF ONE OF US HAD CHANGED ONE BEFORE WE COULD HAVE PREVENTED THIS 'RETURN TO FIELD' OCCURRENCE BY CATCHING OUR MISTAKE AT FINAL INSTALLATION OF THE RUDDER THROW LIMITER PROX SWITCHES.

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.