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A DC8-70 during maintenance test of the altitude alert system the technician discovered conflict between test procedure results and maintenance manual printed results.
| Attributes | |
| ACN | 530190 |
| Time | |
| Date | 200111 |
| Day | Wed |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | DC-8 70 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : parked ground : maintenance |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : lead technician |
| Qualification | technician : powerplant technician : airframe |
| Experience | maintenance avionics : 10 maintenance lead technician : 1 |
| ASRS Report | 530190 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper documentation non adherence : published procedure non adherence : far |
| Independent Detector | other other : person 1 |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : manuals performance deficiency : non compliance with legal requirements |
| Supplementary | |
| Problem Areas | Aircraft Chart Or Publication |
| Primary Problem | Chart Or Publication |
| Situations | |
| Publication | maintenance manual |
Narrative:
The airline supplementary maintenance manual chkout for the altitude alerter system has contradictory statements regarding operation. Maintenance manual page states that when the altitude alerter looses its altitude source it switches to an alternate source 'first officer's' as reflected by statement and is indicated by an 'right.' page 5 says that when an 'right' is indicated it is using the signal from the dadc (digital air data computer). The system defaulted as designed in-flight. The condition did not exist on the ground. It could be duplicated however by removing power from each system. The altitude alerter self-tested correctly on the ground and it was ok for continued service. The issue with the manual has been reported to quality control for further investigation.
Original NASA ASRS Text
Title: A DC8-70 DURING MAINT TEST OF THE ALT ALERT SYS THE TECHNICIAN DISCOVERED CONFLICT BTWN TEST PROC RESULTS AND MAINT MANUAL PRINTED RESULTS.
Narrative: THE AIRLINE SUPPLEMENTARY MAINT MANUAL CHKOUT FOR THE ALT ALERTER SYS HAS CONTRADICTORY STATEMENTS REGARDING OP. MAINT MANUAL PAGE STATES THAT WHEN THE ALT ALERTER LOOSES ITS ALT SOURCE IT SWITCHES TO AN ALTERNATE SOURCE 'FO'S' AS REFLECTED BY STATEMENT AND IS INDICATED BY AN 'R.' PAGE 5 SAYS THAT WHEN AN 'R' IS INDICATED IT IS USING THE SIGNAL FROM THE DADC (DIGITAL AIR DATA COMPUTER). THE SYS DEFAULTED AS DESIGNED INFLT. THE CONDITION DID NOT EXIST ON THE GND. IT COULD BE DUPLICATED HOWEVER BY REMOVING PWR FROM EACH SYS. THE ALT ALERTER SELF-TESTED CORRECTLY ON THE GND AND IT WAS OK FOR CONTINUED SVC. THE ISSUE WITH THE MANUAL HAS BEEN RPTED TO QUALITY CTL FOR FURTHER INVESTIGATION.
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.