A B757-200 was dispatched with the incorrect ATC transponder.

Attributes
ACN	706218
Time
Date	200607
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
ASRS Report	706218
Person 2
Affiliation	company : air carrier
Function	other personnel other
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper documentation maintenance problem : improper maintenance non adherence : far non adherence : published procedure
Independent Detector	other other : stores clerk
Resolutory Action	none taken : detected after the fact
Consequence	other other
Factors
Maintenance	contributing factor : schedule pressure contributing factor : engineering procedure performance deficiency : non compliance with legal requirements performance deficiency : logbook entry performance deficiency : installation
Supplementary
Problem Areas	Maintenance Human Performance Environmental Factor Aircraft Chart Or Publication
Primary Problem	Maintenance Human Performance

Narrative:

Incorrect transponder installed. Replaced transponder with the type that already installed on aircraft. The eco (engineering change order) did not show being accomplished; that is why I went to the aircraft to see what was installed on aircraft. Transponder was changed at a downline station. Will use ipc when multiple company part numbers for same part are installed. There is 3 different company part numbers for fleet. Eco was not being shown on eco listing for this aircraft.

Original NASA ASRS Text

Title: A B757-200 WAS DISPATCHED WITH THE INCORRECT ATC XPONDER.

Narrative: INCORRECT XPONDER INSTALLED. REPLACED XPONDER WITH THE TYPE THAT ALREADY INSTALLED ON ACFT. THE ECO (ENGINEERING CHANGE ORDER) DID NOT SHOW BEING ACCOMPLISHED; THAT IS WHY I WENT TO THE ACFT TO SEE WHAT WAS INSTALLED ON ACFT. XPONDER WAS CHANGED AT A DOWNLINE STATION. WILL USE IPC WHEN MULTIPLE COMPANY PART NUMBERS FOR SAME PART ARE INSTALLED. THERE IS 3 DIFFERENT COMPANY PART NUMBERS FOR FLEET. ECO WAS NOT BEING SHOWN ON ECO LISTING FOR THIS ACFT.

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.