A B757-200 avionics tech notices a discrepancy with the MM procedure for the HF datalink system. The...

Attributes
ACN	774761
Time
Date	200802
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
Qualification	technician : powerplant technician : airframe
Experience	maintenance avionics : 17 maintenance lead technician : 15 maintenance technician : 28
ASRS Report	774761
Events
Anomaly	maintenance problem : improper documentation
Independent Detector	other other : 1
Resolutory Action	none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Company Aircraft Chart Or Publication
Primary Problem	Chart Or Publication

Narrative:

On feb/xa/08; further testing of other aircraft disclosed to me that I overlooked an amm item called out for on the test. The aircraft test was not per the amm (no SELCAL chime or light occurs). I have tested several other aircraft and determined that there is no SELCAL chime or light per the amm. The HF data link system on aircraft XXX does function normal; but the amm is incorrect. I have submitted 5 engineering requests to change B757 amm to reflect the proper test. Callback conversation with reporter revealed the following information: reporter stated their company engineering just recently issued an engineering order for changes to the HF datalink system test procedure. This change informs maintenance that when performing the HF datalink test; to verify that a 'link test successful' message appears on the mcdu. No light or chime will occur. But; engineering also notes that some aircraft may still have either a light or chime happen. Aircraft without the light or chime test response have the new internal software that has been modified.

Original NASA ASRS Text

Title: A B757-200 AVIONICS TECH NOTICES A DISCREPANCY WITH THE MM PROCEDURE FOR THE HF DATALINK SYSTEM. THE REQUIRED SELCAL CHIME OR LIGHT DID NOT OCCUR ON CERTAIN ACFT AS NOTED IN THE MM TEST PROCEDURE.

Narrative: ON FEB/XA/08; FURTHER TESTING OF OTHER ACFT DISCLOSED TO ME THAT I OVERLOOKED AN AMM ITEM CALLED OUT FOR ON THE TEST. THE ACFT TEST WAS NOT PER THE AMM (NO SELCAL CHIME OR LIGHT OCCURS). I HAVE TESTED SEVERAL OTHER ACFT AND DETERMINED THAT THERE IS NO SELCAL CHIME OR LIGHT PER THE AMM. THE HF DATA LINK SYS ON ACFT XXX DOES FUNCTION NORMAL; BUT THE AMM IS INCORRECT. I HAVE SUBMITTED 5 ENGINEERING REQUESTS TO CHANGE B757 AMM TO REFLECT THE PROPER TEST. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THEIR COMPANY ENGINEERING JUST RECENTLY ISSUED AN ENGINEERING ORDER FOR CHANGES TO THE HF DATALINK SYSTEM TEST PROCEDURE. THIS CHANGE INFORMS MAINT THAT WHEN PERFORMING THE HF DATALINK TEST; TO VERIFY THAT A 'LINK TEST SUCCESSFUL' MESSAGE APPEARS ON THE MCDU. NO LIGHT OR CHIME WILL OCCUR. BUT; ENGINEERING ALSO NOTES THAT SOME ACFT MAY STILL HAVE EITHER A LIGHT OR CHIME HAPPEN. ACFT WITHOUT THE LIGHT OR CHIME TEST RESPONSE HAVE THE NEW INTERNAL SOFTWARE THAT HAS BEEN MODIFIED.

Data retrieved from NASA's ASRS site as of May 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.

A B757-200 avionics tech notices a discrepancy with the MM procedure for the HF datalink system. The required SELCAL chime or light did not occur on certain aircraft as noted in the MM test procedure.